Compositions and methods for detecting auxin in vitro and in vivo

Abstract

Provided are compositions and methods for detecting an auxin, as well as methods of preparing the compositions The compositions of the present disclosure provide a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin. The composition may be used in a method for detecting the presence of auxin, the levels of auxin or the distribution of auxin in one or more cells in vitro or in vivo.

Description

COMPOSITIONS AND METHODS FOR DETECTING AUXIN IN VITRO AND IN VIVOFIELD OF INVENTION

[0001] The present invention relates to compositions and methods for detecting an auxin. More specifically, the present invention relates to compositions comprising a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin. The invention also relates to methods and uses of the composition for detecting auxin in vitro and in vivo.BACKGROUND

[0002] As climate change stresses global agricultural production1, there is a pressing need for deeper understanding of the molecular processes inside plants that regulate stress responses, which ultimately affect crop yield and quality2. The integration of nanotechnology-enabled sensors to living plants, or plant nanobionics3, has significantly increased the volume of real-time data that can be gathered from these systems. Recent advancements in this field have resulted in the development of fluorescent-based carbon nanotube sensors for detecting gibberellins4, H2O25, salicylic acid6, and synthetic auxins7, and arsenic8. Building on this success, in this work, a nanosensor that specifically targets the bioactive auxin in plants, indole-3-acetic acid (I AA) is developed. As IAA is a crucial plant hormone that regulates physiological processes9and environmental responses10 11, its application in living plants is thoroughly demonstrated. Natural auxins, such as indole-3-acetic acid (IAA), regulate many physiological processes in plants, including responses to the surrounding environment such as gravitropism, phototropism, hydrotropism, and shade avoidance. At the cellular level, the temporal and gradient distribution of IAA across plant cells affects cellular growth and behavior like cell elongation, division, expansion, and differentiation. Auxin abundance is primarily regulated by its biosynthesis and transport12, while auxin signaling influences the plant response to available auxin10 13. Environmental stresses such as shade avoidance syndrome and thermomorphogenesis also induce IAA levels in plants, causing elongative growth that weakens plant structure and lowers yield14J5. Therefore, realtime visualization of the distribution of auxins, such as IAA, in planta would provide a significant impact on the understanding of how auxin biosynthesis and signalling pathways influence a plant’s response to specific stimuli10 12.

[0003] Multiple techniques have been developed to measure IAA concentration and distribution in plants16. Some of these methods for IAA measurement include indirect quantification via the expression of auxin-responsive genes such as AUXIN / INDOLE-3-ACETIC ACID (Aux / IAA), GRETCHEN HAGEN 3 (GH3), and SMALL AUXIN-UP RNA (SAUR) gene families17, or directquantification of IAA with mass spectrometry18. These methods involve homogenization of plant tissues and extraction of RNA transcripts or metabolites, thus lacking spatial and temporal resolution. To study auxin-dependent developmental processes such as embryogenesis, lateral root formation, and various tropisms9, it is crucial to understand the formation of auxin gradients and local maxima9. Several genetically encoded auxin reporter systems have been developed for visualizing auxin distribution in planta, including synthetic auxin-responsive DR5 promoter (DR5::GUS19, DR5::GFPzo), as well as auxin-responsive protein DH-VENUS21. Dll-VENUS is recently improved into auxin sensors R2D222and C3PO23, which allowed for increased sensitivity and semi-quantitative measurement of auxin.

[0004] Recently, a genetically encoded fluorescent biosensor based on Fluorescence Resonance Energy Transfer (FRET) biosensor “AuxSen” has been developed for direct IAA visualization24. Containing an Escherichia coli tryptophan repressor protein engineered with an IAA- specific binding pocket for reversible binding mechanism, AuxSen allows for direct and spatiotemporal observation of auxin levels in the root apex and its transient changes during auxin uptake and clearance. Development of biologically encoded auxin sensors generally constitute a time-consuming, expensive and laborious process that includes optimization, screening and generating multiple transgenic lines. Furthermore, the optical absorption and emission of these fluorescent biosensors are typically in the blue to yellow spectrum region, which gives sub-optimal in vivo imaging because of weaker tissue penetration, high scattering, and confounding signals from cellular autofluorescence. Therefore, while live imaging of in planta auxin distribution may be carried out in root and young tissues such as shoot apical meristem or leaf initiation, visualization of IAA on matured leaves is limited due to strong interference from chlorophyll autofluorescence. These methods have been well-established for plant sciences and have been used extensively to elucidate mechanisms underlying plant development and responseZ5-29. However, genetically encoded biosensors require the generation of transgenic plants, which is time-consuming and may restrict its use to plant species with established methods for genetic engineering30. It has been a long-standing challenge to develop an effective, yet convenient method for real-time and direct measurements of IAA to monitor plant health across plant species. Thus there is a need for compositions and methods for direct real-time visualization of levels and distribution of auxins both in vitro and in v / vothat does not require genetic manipulation of the cell or cells to which the auxins are to be visualized and provides capabilities to visualize auxin in a variety of live cells, including those of mature plant structures.SUMMARY OF THE INVENTION

[0005] Improved compositions and methods for detecting an auxin are provided herein, as well as methods of preparing the composition. Specifically, the compositions and methods provided herein may detect, in real-time, an auxin presence, level or distribution by directly binding the auxin, whereinthe binding does not require an antibody or a biologically encoded sensor, the detection may be performed with near-infrared fluorescence or photoluminescence and may be performed in a variety of live cells.

[0006] Here the Corona Phase Molecular Recognition (CoPhMoRe) techniques are used to develop a highly selective fluorescent nanosensor on semiconducting single-walled carbon nanotubes (SWNT) for direct detection of IAA. The near infrared (nIR) fluorescence of SWNTs offers enhanced sensitivity and selectivity, superior tissue transparency, and minimal autofluorescence interference331. The corona phase responsible for the recognition motif of IAA was developed by wrapping water-soluble polyamic polymers on the nanotube surface, with the polymer structure designed and inspired by the in vivo interaction between IAA and its protein receptor TRANSPORT INHIBITOR RESPONSE1 (TIR1 )32.

[0007] In this work, it was demonstrated that the CoPhMoRe-based IAA nanosensor shows high specificity to IAA with reversible response, which allows for the measuring of dynamic changes in IAA content. It was then shown that the sensor can be effectively introduced into plant cells and enable realtime imaging of IAA concentration and distribution in leaf tissues. The validation of the present IAA nanosensor in a living plant system was performed through multiple experimental approaches. This includes using XVE::iaaM Arabidopsis plants, which allows for location-specific induction of IAA and thus used to demonstrate the IAA nanosensor in visualizing induced biosynthesis and local transport of IAA within the leaf. As shade avoidance syndrome is a natural plant response that elevates IAA and limits agricultural yield33, it was also demonstrated the IAA nanosensor in measuring dynamic changes in IAA during shade response across various plant species including Nicotiana benthamiana, choy sum {Brassica rapa var. parachinensis), and spinach (Spinacia oleracea). Lastly, it was shown the sensitivity of the disclosed nanosensor in detecting IAA distribution at physiological levels, in various plant tissues like roots and cotyledons.

[0008] In certain embodiments, there is provided herein, a composition comprising: a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin.

[0009] In certain embodiments, the polymer of the polyamic sodium salt may comprise one or more of each of an aromatic dianhydride monomer and an aromatic diamine monomer.

[0010] In certain embodiments, the polymer of the polyamic sodium salt may comprise one or more monomers of each of 4,4'-oxydiphthalic anhydride (OPDA) and 6,6'-diamino-2,2'-bipyridyl (26DAPB).

[0011] In certain embodiments, the polymer of the polyamic sodium salt may be:, wherein n=15-30.

[0012] In certain embodiments, the SWNT may be photoluminescent.

[0013] In certain embodiments, the SWNT may be near-infrared photoluminescent.

[0014] In certain embodiments, a wavelength and / or an intensity of fluorescence of the SWNT in the absence of the adsorbed polymer of the polyamic sodium salt may be different from a wavelength and / or an intensity of fluorescence of the SWNT adsorbed with the polymer of the polyamic sodium salt.

[0015] In certain embodiments, the polymer of the polyamic sodium salt may comprise a wrapping polymer, the wrapping polymer comprising the polymer of the polyamic sodium salt adsorbed to the SWNT in a single-handed helix conformation.

[0016] In certain embodiments, the polymer of the polyamic sodium salt may be adsorbed to the SWNT at about 50 mg / L to about 200 mg / L.

[0017] In certain embodiments, the selective binding site for the auxin may comprise a synthetic indole-3-acetic acid (IAA) binding pocket.

[0018] In certain embodiments, the selective binding site for the auxin may comprise hydrogen bonding and hydrophobic interactions between the auxin and transport inhibitor response 1 (TIR1 ).

[0019] In certain embodiments, the selective binding site for the auxin may comprise at least one of:(i) a salt-bridge interaction between an indole-3-acetic acid (IAA) carboxyl group and a guanidium residue of arginine 403 of transport inhibitor response 1 (TIR1 ) together with hydrogen bonding of the IAA carboxyl group to another hydroxyl residue of TIR1 serine residue 438;(ii) hydrophobic and van der Waals interaction between an indolic group of the IAA and phenyl residues 79 and 82 of the TIR1 ; and(iii) hydrogen bonding between an indolic nitrogen of the IAA and a carbonyl on the side of a TIR1 binding pocket.

[0020] In certain embodiments, the selective binding site may not substantially bind to one or more of: gibberellic acid, abscisic acid, jasmonic acid, salicylic acid, indole-3-propionic acid, indolebutyric acid, L-tryptophan, phenylacetic acid, 2-oxindole-3-acetic acid, indole-3-acetyl-aspartate and 1 -naphthaleneacetic acid.

[0021] In certain embodiments, the auxin may selectively bind the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM or greater.

[0022] In certain embodiments, the estimated dissociation constant coefficient (Kd) of the composition to the auxin may be calculated using:wherein the Kdmay be between about 1 .2 pM and about 5.0 pM, wherein p is proportional factor showing the maximum optical modulation, I is an auxin fluorescence, l0is a normalized fluorescent intensity change before and after addition of I, [0 - IAA] is a total number of binding sites, and [0tota;] is a number of occupied binding sites.

[0023] In certain embodiments, the auxin may comprise indole-3-acetic acid (IAA) and / or indole- 3-pyruvate (IPA).

[0024] In certain embodiments, the auxin may comprise indole-3-acetic acid (IAA).

[0025] In certain embodiments, the IAA and the IPA may have different binding parameters to the selective binding site.

[0026] In certain embodiments, the polymer of the polyamic sodium salt may be free from selective binding to the auxin in the absence of being adsorbed on the SWNT.

[0027] In certain embodiments, there is provided herein, a method of adsorbing a polymer of the polyamic sodium salt as defined in the present disclosure to a single-walled carbon nanotube (SWNT), the method comprising conjugating the polymer of the polyamic sodium salt with the SWNT.

[0028] In certain embodiments, the polymer of the polyamic sodium and the SWNT may be non- covalently conjugated.

[0029] In certain embodiments, the conjugating may comprise sonication.

[0030] In certain embodiments, the method may further comprise a step of forming the SWNT with high-pressure carbon monoxide.

[0031] In certain embodiments, the adsorption of the polymer of the polyamic sodium salt to the SWNT may change a wavelength and / or an intensity of fluorescence of the SWNT.

[0032] In certain embodiments, there is provided herein, a method of detecting an auxin, the method comprising: applying a composition of the present disclosure to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0033] In certain embodiments, there is provided herein, a method of detecting an auxin in vivo, the method comprising: applying a composition of the present disclosure to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0034] In certain embodiments, the organism may be a plant or a plant seed.

[0035] In certain embodiments, the organism may be selected from the group consisting of Nicotiana benthamiana, an Arabidopsis, choy sum (Brassica chinensis var. parachinensis), kai Ian, and spinach (Spinacia oleracea).

[0036] In certain embodiments, the method may further comprise: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a detection or sensor composition of the present disclosure; anddetermining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0037] In certain embodiments, the measured reference wavelength may be subtracted from the measured wavelength and / or the measured reference intensity of fluorescence may be subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.

[0038] In certain embodiments, there is provided herein, a method of detecting a change in an auxin level and / or a change in an auxin distribution, the method comprising: applying a composition of the present disclosure to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0039] In certain embodiments, the measured first wavelength may be subtracted from the measured second wavelength and / or the measured first intensity of fluorescence may be subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0040] In certain embodiments, the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells may comprise a measurement after a duration of time and / or a stimulus.

[0041] In certain embodiments, the stimulus may comprise one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

[0042] In certain embodiments, the method may further comprise: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a composition of the present disclosure; and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0043] In certain embodiments, the measured reference wavelength may be subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence may be subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0044] In certain embodiments, there is provided herein, a kit for detecting an auxin in vivo comprising a composition of the present disclosure and at least one of: instructions for performing a method of the present disclosure; one or more reagent for performing a method of the present disclosure; and one or more buffers.

[0045] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting an auxin, wherein the detecting comprises: applying the composition to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0046] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting an auxin in vivo, wherein the detecting comprises: applying the composition to one or more cells of an organism;measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0047] In certain embodiments, the organism is a plant or a plant seed.

[0048] In certain embodiments, the organism is selected from the group consisting of Nicotiana benthamiana, an Arabidopsis, choy sum (Brassica chinensis var. parachinensis), kai Ian, and spinach Spinacia oleracea).

[0049] In certain embodiments, the use may further comprise: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a detection or sensor composition of the present disclosure; and determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0050] In certain embodiments, the measured reference wavelength may be subtracted from the measured wavelength and / or the measured reference intensity of fluorescence may be subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.

[0051] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting a change in an auxin level and / or a change in an auxin distribution, wherein the detecting comprises: applying the composition to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; anddetermining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0052] In certain embodiments, the measured first wavelength may be subtracted from the measured second wavelength and / or the measured first intensity of fluorescence may be subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0053] In certain embodiments, the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells may comprise a measurement after a duration of time and / or a stimulus.

[0054] In certain embodiments, the stimulus may comprise one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

[0055] In certain embodiments, the use may further comprise: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a detection or sensor composition of the present disclosure; and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0056] In certain embodiments, the measured reference wavelength may be subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence may be subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0057] In certain embodiments, there is provided herein, a polymer of a polyamic sodium salt, wherein the polymer is:, wherein n=15-30.

[0058] In certain embodiments, there is provided herein, a method, process, composition, use, kit, pharmaceutical composition, or compound as substantially described herein.

[0059] In certain embodiments, there is provided, the invention as substantially described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In drawings which illustrates embodiments of the disclosure,

[0061] Figure 1 demonstrates the development of IAA Nanosensor, (a) Schematic diagram illustrating the semi-rational design of the CoPhMoRe IAA sensor based on the in vivo interaction between IAA and the TIR1 binding pocket, resulting in fluorescent modulation upon IAA binding, (b) Heatmap summarizing the nIR fluorescent responses of CoPhMoRe sensors (1 )— (20) (x-axis) to plant analytes (y-axis). Fluorescent intensity was measured before and after the addition of plant analyte (100 pM) using a home-built stand-off nIR camera setup with an excitation wavelength of 785 nm and laser power of 30 mW. Normalized fluorescent intensity changes (I -I o) / l o are shown in a color-coded heatmap where negative values indicate quenching response and positive values indicate turn-on response. Polymer structures of CoPhMoRes are provided in supplementary information, (c) Optical response of CoPhMoRe #3 to 100 pM of IAA at different ionic states (the first two columns) and in various aqueous buffer conditions (the last seven columns). The third column showed the sensor inherent response to 1 % DMSO aqueous solution, (d) Interference of IAA sensor by compounds with similar structure or physiological function in 10 mM MES pH 5.5 buffer. Red columns: Sensor response (l-lo) / lo after addition of IAA analogs and other related metabolites. Cyan columns: Sensor response (l-lo) / lo after addition of 100 pM IAA to solutions already containing interfering compounds. Sensor response represents the final response in the presence of both IAA and interfering molecules, (e) Excitationemission profile showing in vitro response of IAA sensor to 100 pM IAA. The sensor exhibits a reduction in fluorescent intensity for all observed chiralities (designated as pair number (n, m) on the heatmap), (f) Calibration curve of IAA sensor response l / lo to IAA. The dashed fitting curve was plotted based on the Langmuir adsorption model, (g) Reversible IAA response (l-lo) / lo to IAA sensor demonstrated by in situ IAA photodegradation. For b, c, d, and f, data is shown as mean ± s.d. from three independentexperiments (n=3). For e and g, three independent experiments were repeated with similar results (n=3). Trp: L-tryptophan, IPA: indole-3-pyruvic acid, I3C: indole-3-carbinol, IAM: indole-3-acetamide, lAAId: indole-3-acetaldehyde, OxlAA: 2-oxindole-3-acetic acid, lAA-Asp: indole-3-acetyl-aspartate, lAA-Glu: indole-3-acetyl-glutamate, 3IPA: indole-3-propionic acid, IBA: indole-3-butyric acid, PAA: phenylacetic acid, NAA: 1 -naphthaleneacetic acid.

[0062] Figure 2 shows that IAA nanosensor localizes into plant cells, (a) Raman spectra of in vitro SWNT-based IAA nanosensor and W5 buffer. The IAA nanosensor generates the distinctive 1590 cm1Raman G-band, while the W5 buffer does not contain any strong Raman signal in the detected spectra, (b) Bright field images of cells in Arabidopsis leaf blade after infiltration with IAA nanosensor. Top, transverse cross-section. Bottom, abaxial leaf epidermis. Locations indicated by a red cross were subjected to confocal Raman spectroscopy. PM, palisade mesophyll cell. SM, spongy mesophyll cell. AS, air space. EC, epidermal cell. GC, guard cell. PC, pavement cell. Scale, 20 pm. (c) Raman spectra of individual leaf cells and structure in (b). Inset, zoomed in Raman spectra showing 1590 cm'1IAA nanosensor G-band. (d) Protoplasts isolated from Arabidopsis leaves with and without IAA nanosensor infiltration. Locations indicated by a red cross were subjected to confocal Raman spectroscopy. Scale, 10 pm. (e) Average Raman spectra of protoplasts in d (n=3). Inset, zoomed in Raman spectra showing 1525 cm1carotenoid peak and 1590 cm1IAA nanosensor G-band. (f) Schematic diagram of optical- sectioning focal planes from center (Z-center) to surface (Z+2) of the protoplast, (g) Raman spectra of the protoplast center at various focal planes, as illustrated in e. Inset, zoomed in Raman spectra showing 1525 cm1carotenoid peak and 1590 cm'1IAA nanosensor G-band Asterisk (*) indicates IAA nanosensor G-band at 1590 cm'1Raman shift, (h) Bright field image of isolated N. benthamiana protoplast incubated with 5 mg L'1IAA nanosensor overlaid with sensor nIR fluorescence of the sensor (red) under 730 nm excitation. Black arrows indicate the localization of the sensor fluorescence signal inside the isolated protoplast. Scale bar, 5 pm. (i) Localization of IAA nanosensor of different chiralities in the periphery of the isolated protoplast. Similar distribution was observed in 12 biological replicates (n=12). Scale bar, 5 pm. (j) IAA nanosensor fluorescent spectra obtained from the pixels containing the IAA nanosensor (pixels with total fluorescent intensities integrated across 900 - 1450 nm greater than 6600), randomly selected pixels in the surrounding media outside the isolated protoplast, and randomly selected pixels in the center of the isolated protoplast. Data are mean ± s.d. from all the selected pixels.

[0063] Figure 3 shows In vivo validation of IAA nanosensor in XVE::iaaM Arabidopsis plant, (a) Auxin-induced morphological changes in 4-week-old Arabidopsis plants expressing XVE::iaaM. Arrowheads indicate leaves treated with DMSO (mock) or 100 pM p-estradiol for 24 h. Scale bars: 5 mm. (b) Expression of / aa / Wand auxin-responsive gene GH3.3, and IAA level in XVE::iaaM Arabidopsisplants after 1 and 24 h of inducer or DMSO (mock) treatment. Data are mean ± s.d. from three biological replicates (r?=3). (c) nIR fluorescent images showing intensities of reference sensor (upper half) and IAA sensor (bottom half) at different time points. Left: Bright field image of Arabidopsis rosette leaf used for application of reference sensor (white oval) and IAA sensor (red oval) using needle-less syringe infiltration. After topical application of the inducer or mock treatment, plant samples were allowed to rest for 6 h before nIR fluorescence imaging. Three independent experiments were repeated with similar results (n=3). (d) Time-profile average normalized intensity (l / l0) of IAA sensor, reference sensor, and ratiometric intensity obtained from c. Io represents the average fluorescent intensity measured during the first 5 minutes of the experiment. The curves were smoothed with Gaussian smoothing. (Please refer to the Supplementary Information for original sensor response from raw data), (e) IAA distribution at each corresponding time point in c estimated using the correlation model between ratiometric signal and local IAA concentration (see supplementary information), (f) Time-profile average IAA concentration obtained from d and e. (g) Average normalized ratiometric responses to different p-estradiol concentrations. Mock: DMSO treatment. Corresponding shades represent the standard deviation from the mean of three independent biological samples (n=3). (h) Corresponding average IAA concentration profiles estimated from h.

[0064] Figure 4 shows local transport of Auxin in Arabidopsis Leaf, (a) Schematic diagram illustrating p-estradiol treatment spot and other parts of the treated leaf, p-estradiol was locally applied in spherical treated spots near the leaf margin on one side of rosette leaf blades of XVE::iaaM Arabidopsis plants. The model domain for auxin transport analysis is a one-dimensional line on the p- estradiol-treated half of the leaf, spanning from the midvein to the leaf margin, (b) Bright field image of a typical Arabidopsis rosette used for local transport of auxin experiment. ROIs A, B, C, D, T, and U are colored on top of the image. U: untreated side; T: treated spot; A: toward base spot at midvein side; B: toward base spot at edge side; C: toward apex spot at midvein side; D: toward apex spot at edge side, (c) iaaMand GH3.3 gene expressions in p-estradiol-treated spot, treated side (excluding treated spot), and untreated side. Sample collected from the treated side excludes the treated spot. Data are mean ± s.d. from three biological replicates (n=3). (d) Normalized fluorescent intensity images of leaf sample in b at different time points showing quenching response of IAA sensor at treated area. After topical application of the inducer at the treated spot, plant samples were allowed to rest for 6 h before nIR fluorescence imaging, (e) Estimated IAA distribution of leaf sample in B at different time points, (f) Average time-profile concentration curves of IAA at designated spots on treated Arabidopsis leaf. Shaded regions indicate standard deviation of pixels in selected regions of interest, (g) A strip of data centered around the induced spot was averaged into one dimension for data fitting with model, (h) Dimensionless model (Equations 2-4) was fit to data at each time point shown above using parameters a-yT<|>:and kmargin. Only light magenta region labeled “Fitted Region” was used for fitting model to avoidartifacts at edges of sensor spots. A residual plot of [IAA]modei- [IAA]datais shown beneath each fit. Blue points in residual plots correspond to “Fitted Region” points.

[0065] Figure 5 shows spatiotemporal distribution of IAA in N. benthamiana under shade condition, (a) Experiment setup for shade stress experiment on N. benthamiana. (b) Normalized fluorescent intensity change images of sensor-functionalized N. benthamiana leaf under shade condition at different time points, showing quenching response of IAA sensor (right spot) relative to reference sensor (left spot), (c) Time-profile average normalized intensity (l / l0) of IAA sensor, reference sensor, and ratiometric intensity obtained from b. Corresponding shades represent standard deviation for each pixel in sensor area. The curves were smoothed with Gaussian smoothing. (Please refer to the Supplementary Information for original sensor response from raw data) (d) Average IAA level determined by LC / MS in whole N. benthamiana leaf at onset of shade response at different time points, (e) Corresponding estimated IAA from b. (f) Time-profile average normalized intensity (l / lo) of IAA concentration from b-e. (g) Normalized fluorescent images of N. benthamiana leaf where one half of leaf blade was functionalized with IAA sensor, showing spatial and temporal distribution of IAA at onset of shade response. Leaf tip is towards the top of the image, while the leaf base is towards the bottom, (h) Calculated spatial and temporal distribution of local IAA concentration derived from normalized images in g. Three independent biological experiments were repeated with similar results (n=3). (i) Change in endogenous IAA concentration in different parts of N. benthamiana leaf under shade condition over different time points. Data represents mean ± s.d from three biological replicates (n=3). (j) Illustration showing different parts of N. benthamiana leaf.

[0066] Figure 6 shows that IAA nanosensor measures IAA distribution during root gravitropic response and in light-grown seedlings, (a and b) nIR fluorescence images of (a) Arabidopsis and (b) tomato root tip that was functionalized with IAA nanosensor and undergoing gravitropic response. nIR images were taken using the stand-off nIR camera. U, upper side of root tip. L, lower side of root tip. g indicates direction of gravity, (c) nIR confocal microscopy of Arabidopsis root tip functionalized with IAA nanosensor and undergoing gravitropic response. Low nIR indicates high IAA content, g indicates direction of gravity. Scale, 50 pm. (d) Comparison between IAA nanosensor and DR5-GFP in the cotyledon of light-grown Arabidopsis seedlings. Arrowheads indicate high lAA / auxin content. Red arrowhead, cotyledon apex. Blue arrowhead, cotyledon edge.

[0067] Figure 7 shows synthesis of polyamic sodium salts. Synthesis scheme of a series polyamic acid sodium salt analogues by combination with different dianhydride and diamine monomers. NMP: N-methyl-2-pyrrolidone; rt: room temperature; PMDA, pyromellitic dianhydride; BPDA, 3, 3’, 4,4’- biphenyltetracarboxylic dianhydride; OPDA, 4,4’-oxydiphthalic anhydride; 34OPDA, 3,4’-oxydiphthalicanhydride; 6FDA, 4,4’-(hexafluoroisopropylidene)diphthalic anhydride, DPSDA, 3, 3’, 4,4’- diphenylsulfonetetracarboxylic dianhydride; 34PA, 3, 4’-bithphalic anhydride; EPDA, 4,4’-(ethyne-1 ,2- diyl)diphthalic anhydride; 26DAPyr, 2,6-diaminopyridine; 26DABP, 6,6’-diamino-2,2’-bipyridyl; 24DABP, 4,4’-diamino-2,2’-bipyridyl; DCBZ, 3,6-diaminocarbazole; DHBZ, 3,3’-dihydroxybenzidine; DBTZ, 2,2- diamino-4,4’-bithiazole.

[0068] Figure 8 shows polymer structures of polyamic acid sodium salts used in the suspension of SWNTs for IAA screening. Abbreviations are listed in Fig. 7.

[0069] Figure 9 shows UV-vis-nIR absorption spectrum of CoPhMoRe candidates for IAA screening, (a) PMDA-26DABP-Na-SWNT. (b) BPDA-26DABP-Na-SWNT. (c) OPDA-26DABP-Na- SWNT. (d) PMDA-24DABP-Na-SWNT. (e) BPDA-24DABP-Na-SWNT. (f) OPDA-24DABP-Na-SWNT. (g) PMDA-26DAPyr-Na-SWNT. (h) BPDA-26DAPyr-Na-SWNT. (i) OPDA-26DAPyr-Na-SWNT. (j) OPDA-DCBZ-Na-SWNT. (k) OPDA-DHBZ-Na-SWNT. (I) OPDA-DBTZ-Na-SWNT. (m) BPDA-DCBZ- Na-SWNT. (n) BPDA-DHBZ-Na-SWNT. (o) BPDA-DBTZ-Na-SWNT. (p) 34OPDA-26DABP-Na-SWNT. (q) 6FDA-26DABP-Na-SWNT. (r) DPSDA-26DABP-Na-SWNT. (s) 34PA-26DABP-Na-SWNT. (t) EPDA-26DABP-Na-SWNT. Abbreviations are listed in Fig. 7.

[0070] Figure 10 shows photoabsorption of IAA sensor before (without IAA) and after the addition of de-protonated IAA (+ lAA-Na, 100 pM) or protonated IAA (IAA-H, 100 pM).

[0071] Figure 11 shows the effect of SWNT chirality on IAA sensing, (a) Calibration curves of sensor response versus IAA concentration for SWNT chiralities (6,5), (8,4), (7,5), (7,6), (9,4), and (10,2) and their corresponding fits, (b, c) Scatter plots representing two fit parameters p and Kdfrom Langmuir isotherm model versus different SWNT chiralities in terms of tube diameters. In a-c, the error bars are standard deviation obtained from three different measurements (n=3).

[0072] Figure 12 shows the relationship between surface coverage q / Kd and normalized fluorescence response of CoPhMoRe library to plant hormones (100 pM). Error bars indicate standard deviation from three independent measurements.

[0073] Figure 13 shows the binding competition between IAA and IPA. Kinetic response of IAA nanosensor in the presence of both IAA and IPA at 1 :10 molar ratio. Initial addition of IAA to the IAA nanosensor resulted in fluorescence quenching. Subsequent adding of IPA resulted in an immediate turn-on response. The turn-on signal then subsequently quenched to the new equilibrium state, which depends on the ratio between IAA and IPA in the solution. This observation indicates that IPA has fast binding kinetics to the IAA nanosensor, but binding of IAA to the nanosensor is more thermodynamicallyfavorable. Three independent meaurements were repeated with similar results (n=3). IAA, indole-3- acetic acid; IPA, indole-3-pyruvic acid. Arrows indicate time-points of adding IAA and IPA.

[0074] Figure 14 shows sensor responsiveness based on in situ IAA photodegradation study, (a) Degradation of IAA due to prolonged exposure to 600 nm excitation source as showed by UV-Vis absorption, (b) Simplified model showed the binding activity of IAA nanosensor to IAA during photodegradation, (c) Comparison between kinetic response of IAA sensor to IAA (as shown by fluorescent recovery kinetics, cyan line) and IAA degradation rate (red line). IAA, indole-3-acetic acid; OxlAA, 2-oxindole-3-acetic acid.

[0075] Figure 15 shows phenotype and chlorophyll content of Arabidopsis leaves infiltrated with or without IAA nanosensor, (a) Phenotype of Arabidopsis plants without or with infiltration. Infiltrated plants were observed at 6, 24, and 48 h post-infiltration. Red arrowhead, leaf infiltrated with IAA nanosensor. Blue arrowhead, leaf infiltrated with 10 mM MES buffer (pH 5.5). Scale, 3 cm. (b) Dissected leaves infiltrated with IAA nanosensor or MES buffer in (a). Scale, 1 cm. (c) Total chlorophyll content of leaves infiltrated with IAA nanosensor or MES buffer in (b). n=3. Values represent mean ± standard deviation.

[0076] Figure 16 shows that IAA nanosensor localized towards the center of Arabidopsis protoplast, (a) Bright field image of protoplast isolated from Arabidopsis leaf blade infiltrated with the IAA nanosensor. Optical-sectioning focal plane was set at the center of the protoplast (Z-center). Locations indicated by a red cross were subjected to confocal Raman spectroscopy. Scale, 10 pm. (b) Raman spectra of protoplast locations in a, showing 1525 cm'1carotenoid peak and 1590 cm'1IAA nanosensor G-band.

[0077] Figure 17 shows that IAA nanosensor localizes into Nicotiana benthamiana leaf cells after infiltration, (a) Bright field images of cells in N. benthamiana leaf blade after infiltration with IAA nanosensor. Top, transverse cross-section. Bottom, abaxial leaf epidermis. Locations indicated by a red cross were subjected to confocal Raman spectroscopy. Scale, 20 pm. (b) Raman spectra of individual leaf cells and structure in a. Inset, zoomed in Raman spectra showing 1590 cm1IAA nanosensor G- band. (c) Protoplasts isolated from N. benthamiana with and without IAA nanosensor infiltration. Locations indicated by a red cross were subjected to confocal Raman spectroscopy. Scale, 10 pm. (d) Average Raman spectra of protoplasts in c. n = 4. Inset, zoomed in Raman spectra showing 1525 cm'1carotenoid peak and 1590 cm'1IAA nanosensor G-band. Asterisk (*) indicates IAA nanosensor G-band at 1590 cm'1Raman shift.

[0078] Figure 18 shows Inducible expression of iaaM by varying [3-estradiol concentrations and time course induction in XVE::iaaM Arabidopsis plants, (a) 10-d-old seedlings of different XVE::iaaM Arabidopsis transgenic T2 lines were subjected to 50 pM p-estradiol induction (+) overnight (16 h) under continuous light. Expression of iaaM at different concentrations of p-estradiol (0-100 pM) for 6 h. (b) or at different time points with 50 pM p-estradiol. (c) under continuous light in XVE::iaaM transgenic Arabidopsis lines (#5, 6, and 7). Data are mean ± s.d. from three biological replicates (n=3).

[0079] Figure 19 shows Auxin-induced phenotypic changes of XVE::iaaM Arabidopsis leaves under p-estradiol treatment. 4-w-old Arabidopsis plants expressing XVE::iaaM were applied with DMSO (mock) or 100 pM p-estradiol using a paintbrush to induce the expression of iaaM. (a) Rosette leaves after 24 h of mock or p-estradiol treatment on the whole leaf blade. Arrow heads represent curled leaves. Scale bar, 1 cm. (b) Measurement of leaf hyponasty after 24 h of p-estradiol treatment. Data are mean ± s.d. (n=15). ***p < 0.001. (c) Local p-estradiol. Top panel indicates detached leaves while bottom panel indicates the whole plants. Left (no treatment), middle (side treatment), and right (middle leaf treatment). Black circles indicate positions of local p-estradiol treatment. Arrow heads represent curled leaves. 10 independent biological experiments were repeated with similar results (n=5). Scale bars, 1 cm.

[0080] Figure 20 shows the optical modulation of reference sensor (AT)I5-SWNT against plant analytes. The screening was carried out using 1 mg / L (AT)15-SWNT in 10 mM MES buffer pH 5.5 with 100 pM of respective plant analytes. The error bars represent standard deviation of triplicate.

[0081] Figure 21 shows the total chlorophyll content of Arabidopsis leaves after exposure to excitation laser of stand-off nIR camera system. Welch’s / -test was used to determine statistical difference compared to 0 h of laser exposure, n.s., not significant.

[0082] Figure 22 shows dose-dependent response of IAA nanosensor to p-estradiol concentration, (a) Maximum quenching ratiometric response as a function of increasing p-estradiol concentration, (b) Estimated maximum IAA increase predicted by the sensor in response to p-estradiol. Values represent mean ± standard deviation.

[0083] Figure 23 shows detection of IAA basal level using IAA biosynthesis inhibitors, (a) Bright field and normalized nIR images of N. benthamiana leaf infiltrated with IAA nanosensor. At t = 45 min, an IAA inhibitor solution (50 pM Yucasin and 10 pM L-Kynurenine) was topically applied to the left side of the leaf, while a mock solution was topically applied to the right side. I / Io, time-profile average normalized intensity, (b) Average time-series profile illustrating the normalized response of the IAAsensor and its corresponding IAA level change in inhibitor-treated area and mock area. The shaded area represents the standard deviation across three independent biological samples (n=3).

[0084] Figure 24 shows average ratiometric response of IAA nanosensor to SAS in N. benthamiana. The normal light condition is set at PAR value of 100 pmol nr2s-1using LED white light set up. The shaded area in each plot represents standard deviation (n=3).

[0085] Figure 25 shows SAS detection in leafy vegetables, (a) Bright field and simulated IAA distribution based on IAA sensor response at different time points during SAS. (b-c) Time-profile average ratiometric intensity (left x-axis) and average IAA level change (right x-axis) in (b) choy sum and (c) spinach. The shaded area in each plot represents standard deviation (n=3).

[0086] Figure 26 shows that IAA sensor senses IAA accumulation in N. benthamiana under heat stress, (a) Bright field and normalized nIR images of N. benthamiana leaf infiltrated with IAA nanosensor. Plants were subjected to heat stress from t = 45 mins onwards, (b) Average time-series profile illustrating the normalized response of the IAA sensor and its corresponding IAA level change under heat stress. The shaded area represents the standard deviation across three independent biological samples (n=3).

[0087] Figure 27 shows validation of roots functionalized with IAA nanosensor, (a) Confocal Raman spectroscopy was used to test different methods to introduce the IAA nanosensor into WT Arabidopsis root tips. IAA nanosensor is characterized by the Raman G-band (red arrowhead, 1590 cm-1Raman shift) and two other minor Raman peaks (blue arrowhead, 842 cm'1and 1286 cm-1Raman shift). Raman spectra shown are the average taken from biological replicates. n=3. (b) Bright field and nIR image of WT Arabidopsis seedlings incubated in half-strength MS liquid media (1 / 2 MS) with or without IAA nanosensor for 2 d. n=3.

[0088] Figure 28 shows that Dll-VENUS measures change in auxin distribution during gravitropic response. U, upper half of root tip. L, lower half of root tip. Scale, 100 pm. White arrow indicates direction of gravity. Three independent experiments were repeated with similar results (n=3).

[0089] Figure 29 shows original data of nanosensor responses in figures 3d and 5c. They show the average normalized response (l / l0) of IAA nanosensor and reference nanosensor, as extracted from the original data sources prior to smoothing and further image processing. (A) IAA sensor and reference sensor response in XVE::iaaM Arabidopsis as shown in figure 3c-d. (B) IAA sensor and reference sensor response in wild-type Nicotiana benthamiana under shade treatment as shown in figure 5b-c.DETAILED DESCRIPTION

[0090] In the context of the present disclosure, various terms are used in accordance with what is understood to be the ordinary meaning of those terms.

[0091] Described herein are compositions, methods and uses comprising a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT). It will be appreciated that embodiments and examples are provided herein for illustrative purposes intended for those skilled in the art, and are not meant to be limiting in any way.

[0092] As used herein, the term “about” refers to an approximately + / -10 % variation from a given value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0093] As used herein, the term “substantially” refers to an approximately +1-5 % variation from a given value. If a value is not used, then substantially means almost completely, but perhaps with some variation, contamination and / or additional component. In some embodiments, “substantially” may include completely.

[0094] As used herein, the term “adsorb” or “adsorption” refers to an ability of a solid, such as a single walled carbon nanotube (SWNT), to bind a molecule, such as a polymer of a polyamic sodium salt, present in a gas or liquid, on a surface of the solid.

[0095] As used herein, the term “sensor” or “nanosensor” may comprise a polymer or composition that provides selective binding to one or more molecules, wherein the composition detects or acts as a sensor or nanosensor for the presence of said one or more molecules. In certain embodiments, the detecting may comprise sensing and / or the sensing may comprise detecting.

[0096] As used herein, an auxin refers to a class of plant hormones, such as indole-3-acetic acid (IAA), that regulate processes in a plant or cell thereof including, but not limited to, cell division, cell elongation, apical dominance, stimulation of secondary growth in the vascular cambium, inducing the formation of adventitious roots and promoting fruit growth. As would be known to the person of skill, IAA is the most common naturally occurring auxin. In certain embodiments, the auxin may comprise a synthetic auxin. In certain embodiments, the auxin may comprise indole-3-acetic acid, 4-chloroindole- 3-acetic acid, phenylacetic acid, indole-3-butyric acid, indole-3-propionic acid or any precursor or intermediate molecule thereof. In certain embodiments, the auxin may be indole-3-acetic acid (IAA) and / or indole-3-pyruvate (IPA). In certain embodiments, the auxin may be IAA.

[0097] In certain embodiments, there is provided herein, composition comprising: a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin.

[0098] A polyamic sodium salt, as would be known to the skilled person, is a water-soluble form of a polyamic acid. Polymers of polyamic sodium salts may be formed by, for example, a condensation reaction between an aromatic dianhydride and aromatic diamines. In certain embodiments, the polyamic sodium salts may be amphilic. In certain embodiments, the polyamic salt salts may comprise monomeric units comprising desired a functional group(s). In certain embodiments, the length of the polymer of the polyamic sodium salt and / or the functional groups present on the polyamic sodium salt may result in a selective binding site for an auxin when said polymer is adsorbed to a single-walled carbon nanotube. In certain embodiments, the polymer of the polyamic sodium salt may be 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 , 62, 63. 64. 65. 66. 67. 68. 69. 70. 71 . 72. 73. 74. 75. 76. 77. 78. 79. 80. 81 . 82. 83. 84. 85. 86. 87. 88. 89.90, 91 , 92, 93, 94, 9 5, 96, 97, 98, 99, 10( , 101 , 102, 103, 104 , 105, 106, 107, 108, 109, 110, 1 11 , 1 12, 1 13, 1 14, 1 15, 1 16, 117, 1 18, 1 19, 120, 121 , 122, 123, 124, 125, 126, 127, 128, 129, 130, 131 , 132, 133, 134, 135, 136, 137, 138, 139, 140, 141 , 142, 143, 144, 145, 146, 147, 148, 149, 150, 151 , 152, 153, 154, 155, 156, 157, 158, 159, 160, 161 , 162, 163, 164, 165, 166, 167, 168, 169, 170, 171 , 172, 173, 174, 175, 176, 177, 178, 179, 180, 181 , 182, 183, 184, 185, 186, 187, 188, 189, 190, 191 , 192, 193, 194, 195, 196, 197, 198, 199, 200, 201 , 202, 203, 204, 205, 206, 207, 208, 209, 210, 21 1 , 212, 213, 214, 215, 216, 217, 218, 219, 220, 221 , 222, 223, 224, 225, 226, 227, 228, 229, 230, 231 , 232, 233, 234, 235, 236, 237, 238, 239, 240, 241 , 242, 243, 244, 245, 246, 247, 248, 249, 250, 251 , 252, 253, 254, 255, 256, 257, 258, 259, 260, 261 , 262, 263, 264, 265, 266, 267, 268, 269, 270, 271 , 272, 273, 274, 275, 276, 277, 278, 279, 280, 281 , 282, 283, 284, 285, 286, 287, 288, 289, 290, 291 , 292, 293, 294, 295, 296, 297, 298, 299, 300, 301 , 302, 303, 304, 305, 306, 307, 308, 309, 310, 31 1 , 312, 313, 314, 315, 316, 317, 318, 319, 320, 321 , 322, 323, 324, 325, 326, 327, 328, 329, 330, 331 , 332, 333, 334, 335, 336, 337, 338, 339, 340, 341 , 342, 343, 344, 345, 346, 347, 348, 349, 350, 351 , 352, 353, 354, 355, 356, 357, 358, 359, 360, 361 , 362, 363, 364, 365, 366, 367, 368, 369, 370, 371 , 372, 373, 374, 375, 376, 377, 378, 379, 380, 381 , 382, 383, 384, 385, 386, 387, 388, 389, 390, 391 , 392, 393, 394, 395, 396, 397, 398, 399, 400, 401 , 402, 403, 404, 405, 406, 407, 408, 409, 410, 41 1 , 412, 413, 414, 415, 416, 417, 418, 419, 420, 421 , 422, 423, 424, 425, 426, 427, 428, 429, 430, 431 , 432, 433, 434, 435, 436, 437, 438, 439, 440, 441 , 442, 443, 444, 445, 446, 447, 448, 449, 450, 451 , 452, 453, 454, 455, 456, 457, 458, 459, 460, 461 , 462, 463, 464, 465, 466, 467, 468, 469, 470, 471 , 472, 473, 474, 475, 476, 477, 478, 479, 480, 481 , 482, 483, 484, 485, 486, 487, 488, 489, 490, 491 , 492,493, 494, 495, 496, 497, 498, 499, 500, 501 , 502, 503, 504, 505, 506, 507, 508, 509, 510, 51 1 , 512,513, 514, 515, 516, 517, 518, 519, 520, 521 , 522, 523, 524, 525, 526, 527, 528, 529, 530, 531 , 532,533, 534, 535, 536, 537, 538, 539, 540, 541 , 542, 543, 544, 545, 546, 547, 548, 549, 550, 551 , 552,553, 554, 555, 556, 557, 558, 559, 560, 561 , 562, 563, 564, 565, 566, 567, 568, 569, 570, 571 , 572,573, 574, 575, 576, 577, 578, 579, 580, 581 , 582, 583, 584, 585, 586, 587, 588, 589, 590, 591 , 592,593, 594, 595, 596, 597, 598, 599, 600, 601 , 602, 603, 604, 605, 606, 607, 608, 609, 610, 61 1 , 612,613, 614, 615, 616, 617, 618, 619, 620, 621 , 622, 623, 624, 625, 626, 627, 628, 629, 630, 631 , 632,633, 634, 635, 636, 637, 638, 639, 640, 641 , 642, 643, 644, 645, 646, 647, 648, 649, 650, 651 , 652,653, 654, 655, 656, 657, 658, 659, 660, 661 , 662, 663, 664, 665, 666, 667, 668, 669, 670, 671 , 672,673, 674, 675, 676, 677, 678, 679, 680, 681 , 682, 683, 684, 685, 686, 687, 688, 689, 690, 691 , 692,693, 694, 695, 696, 697, 698, 699, 700, 701 , 702, 703, 704, 705, 706, 707, 708, 709, 710, 71 1 , 712,713, 714, 715, 716, 717, 718, 719, 720, 721 , 722, 723, 724, 725, 726, 727, 728, 729, 730, 731 , 732,733, 734, 735, 736, 737, 738, 739, 740, 741 , 742, 743, 744, 745, 746, 747, 748, 749, 750, 751 , 752,753, 754, 755, 756, 757, 758, 759, 760, 761 , 762, 763, 764, 765, 766, 767, 768, 769, 770, 771 , 772,773, 774, 775, 776, 777, 778, 779, 780, 781 , 782, 783, 784, 785, 786, 787, 788, 789, 790, 791 , 792,793, 794, 795, 796, 797, 798, 799, 800, 801 , 802, 803, 804, 805, 806, 807, 808, 809, 810, 811 , 812,813, 814, 815, 816, 817, 818, 819, 820, 821 , 822, 823, 824, 825, 826, 827, 828, 829, 830, 831 , 832,833, 834, 835, 836, 837, 838, 839, 840, 841 , 842, 843, 844, 845, 846, 847, 848, 849, 850, 851 , 852,853, 854, 855, 856, 857, 858, 859, 860, 861 , 862, 863, 864, 865, 866, 867, 868, 869, 870, 871 , 872,873, 874, 875, 876, 877, 878, 879, 880, 881 , 882, 883, 884, 885, 886, 887, 888, 889, 890, 891 , 892,893, 894, 895, 896, 897, 898, 899, 900, 901 , 902, 903, 904, 905, 906, 907, 908, 909, 910, 911 , 912,913, 914, 915, 916, 917, 918, 919, 920, 921 , 922, 923, 924, 925, 926, 927, 928, 929, 930, 931 , 932,933, 934, 935, 936, 937, 938, 939, 940, 941 , 942, 943, 944, 945, 946, 947, 948, 949, 950, 951 , 952,953, 954, 955, 956, 957, 958, 959, 960, 961 , 962, 963, 964, 965, 966, 967, 968, 969, 970, 971 , 972,973, 974, 975, 976, 977, 978, 979, 980, 981 , 982, 983, 984, 985, 986, 987, 988, 989, 990, 991 , 992,993, 994, 995, 996, 997, 998, 999, or 1000 units of the two monomers.

[0099] In certain embodiments, the polymer of the polyamic sodium salt may be formed by one or more of each of an aromatic dianhydride monomer and an aromatic diamine monomer. In certain embodiments, the dianhydride monomer may be pyromellitic dianhydride (PMDA), 3,3, 4,4 - Biphenyltetracarboxylic dianhydride (BPDA), 4,4’-oxydiphthalic anhydride (OPDA), 3,4’-oxydiphthalic anhydride (34OPDA), 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3, 3’, 4,4’- diphenylsulfonetetracarboxylic dianhydride (DPSDA), 3,4’-bithphalic anhydride (34PA) or 4,4’-(ethyne- 1 ,2-diyl)diphthalic anhydride (EPDA). In certain embodiments the diamine monomer may be 2,6- diaminopyridine (26DAPyr), 6,6’-diamino-2,2’-bipyridyl (26DABP), 4,4’-diamino-2,2’-bipyridyl (24DABP), 3,6-diaminocarbazole (DCBZ), 3,3’-dihydroxybenzidine (DHBZ) or 2,2-diamino-4,4’-bithiazole (DBTZ). In certain embodiments, the polymer may comprise one or more monomers of each of 4,4'-oxydiphthalic anhydride (OPDA) and 6,6'-diamino-2,2'-bipyridyl (26DAPB). In certain embodiments, the polymer may comprise:, wherein n may be 15-30.

[0100] In certain embodiments, a polymer of a polyamic sodium salt may comprise a polymer selected to have a length of a hydrophilic region and / or length of a hydrophobic region configured to interact in with an auxin. In certain embodiments, the length of the polymer of a polyamic sodium salt may be adjusted.

[0101] In certain embodiments, the single-walled carbon nanotube (SWNT) may be a fluorescent, a photoluminescent, a near infrared (nIR) fluorescent or a nIR photoluminescent SWNT. In certain embodiments, the single-walled nanotube may be formed by high-pressure carbon monoxide. In certain embodiments, a wavelength and / or an intensity of fluorescence of the SWNT in the absence of the adsorbed polymer of the polyamic sodium salt may be different from a wavelength and / or an intensity of fluorescence of the SWNT adsorbed with the polymer of the polyamic sodium salt.

[0102] In certain embodiments, the polymer of the polyamic sodium salt may be adsorbed on a single-walled carbon nanotube (SWNT). In certain embodiments, the adsorption of the polymer of the polyamic sodium salt to the SWNT may form one or more corona phase. In certain embodiments, the polymer of the polyamic sodium salt may be adsorbed to the SWNT by non-covalent interactions. A corona phase may comprise an adsorbed phase of a surfactant or a polymer on a nanoparticle, such as for example a polymer of a polyamic sodium salt adsorbed on a SWNT. In certain embodiments, the corona phase may comprise a combination of corona phases. In certain embodiments, the corona phase or combination of corona phases may comprise a selective binding site for binding an auxin. In certain embodiments, the polymer of the polyamic sodium salt may comprise a wrapping polymer, wherein the wrapping polymer may comprise the polymer of the polyamic sodium salt adsorbed to the SWNT in a single-handed helix conformation. In certain embodiments, the polymer adsorbed on the SWNT may show photoabsorption spectra showing absorption chirality peaks in the Sn and S22 region.

[0103] In certain embodiments, the polymer of the polyamic sodium salt may be adsorbed to the SWNT at about 50 mg / L to about 200 mg / L. In certain embodiments, the polymer of the polyamic sodiumsalt may be adsorbed to the SWNT at about 50 mg / L, about 51 mg / L, about 52 mg / L, about 53 mg / L, about 54 mg / L, about 55 mg / L, about 56 mg / L, about 57 mg / L, about 58 mg / L, about 59 mg / L, about 60 mg / L, about 61 mg / L, about 62 mg / L, about 63 mg / L, about 64 mg / L, about 65 mg / L, about 66 mg / L, about 67 mg / L, about 68 mg / L, about 69 mg / L, about 70 mg / L, about 71 mg / L, about 72 mg / L, about 73 mg / L, about 74 mg / L, about 75 mg / L, about 76 mg / L, about 77 mg / L, about 78 mg / L, about 79 mg / L, about 80 mg / L, about 81 mg / L, about 82 mg / L, about 83 mg / L, about 84 mg / L, about 85 mg / L, about 86 mg / L, about 87 mg / L, about 88 mg / L, about 89 mg / L, about 90 mg / L, about 91 mg / L, about 92 mg / L, about 93 mg / L, about 94 mg / L, about 95 mg / L, about 96 mg / L, about 97 mg / L, about 98 mg / L, about 99 mg / L, about 100 mg / L, about 101 mg / L, about 102 mg / L, about 103 mg / L, about 104 mg / L, about 105 mg / L, about 106 mg / L, about 107 mg / L, about 108 mg / L, about 109 mg / L, about 1 10 mg / L, about 1 1 1 mg / L, about 1 12 mg / L, about 1 13 mg / L, about 1 14 mg / L, about 1 15 mg / L, about 1 16 mg / L, about 1 17 mg / L, about 1 18 mg / L, about 1 19 mg / L, about 120 mg / L, about 121 mg / L, about 122 mg / L, about 123 mg / L, about 124 mg / L, about 125 mg / L, about 126 mg / L, about 127 mg / L, about 128 mg / L, about 129 mg / L, about 130 mg / L, about 131 mg / L, about 132 mg / L, about 133 mg / L, about 134 mg / L, about 135 mg / L, about 136 mg / L, about 137 mg / L, about 138 mg / L, about 139 mg / L, about 140 mg / L, about 141 mg / L, about 142 mg / L, about 143 mg / L, about 144 mg / L, about 145 mg / L, about 146 mg / L, about 147 mg / L, about 148 mg / L, about 149 mg / L, about 150 mg / L, about 151 mg / L, about 152 mg / L, about 153 mg / L, about 154 mg / L, about 155 mg / L, about 156 mg / L, about 157 mg / L, about 158 mg / L, about 159 mg / L, about 160 mg / L, about 161 mg / L, about 162 mg / L, about 163 mg / L, about 164 mg / L, about 165 mg / L, about 166 mg / L, about 167 mg / L, about 168 mg / L, about 169 mg / L, about 170 mg / L, about 171 mg / L, about 172 mg / L, about 173 mg / L, about 174 mg / L, about 175 mg / L, about 176 mg / L, about 177 mg / L, about 178 mg / L, about 179 mg / L, about 180 mg / L, about 181 mg / L, about 182 mg / L, about 183 mg / L, about 184 mg / L, about 185 mg / L, about 186 mg / L, about 187 mg / L, about 188 mg / L, about 189 mg / L, about 190 mg / L, about 191 mg / L, about 192 mg / L, about 193 mg / L, about 194 mg / L, about 195 mg / L, about 196 mg / L, about 197 mg / L, about 198 mg / L, about 199 mg / L, or about 200 mg / L.

[0104] In certain embodiments, the composition may comprise a selective binding site for an auxin. As used herein, a selective binding site for an auxin may comprise a portion of the composition, such as a corona phase or combination of corona phases formed by a polymer of a polyamic sodium salt adsorbed on a SWNT that exhibits a specific binding for an auxin. In certain embodiments, the selective binding site may not bind a substantial number or amount of molecules that are not auxin. In certain embodiments, the selective binding site may comprise a synthetic indole-3-acetic acid (IAA) binding pocket. The synthetic IAA binding pocket may comprise any binding site that provides selective binding to an auxin. In certain embodiments, the selective binding site may comprise a binding site that mimics or copies the hydrogen bonding and hydrophobic interactions that occur between the auxin, such as IAA, and transport inhibitor response 1 (TIR1 ). In certain embodiments, the binding site maycomprise a binding site mimicking or copying one or more of the following interactions between IAA andTIR1 :(i) a salt-bridge interaction between an indole-3-acetic acid (IAA) carboxyl group and a guanidium residue of arginine 403 of transport inhibitor response 1 (TIR1 ) together with hydrogen bonding of the IAA carboxyl group to another hydroxyl residue of TIR1 serine residue 438;(ii) hydrophobic and van der Waals interaction between an indolic group of the IAA and phenyl residues 79 and 82 of the TIR1 ; and(iii) hydrogen bonding between an indolic nitrogen of the IAA and a carbonyl on the side of a TIR1 binding pocket.In certain embodiments, the TIR1 may comprise any TIR1 orthologue or paralogue. In certain embodiments, the selective binding site may not substantially bind to one or more of gibberellic acid, abscisic acid, jasmonic acid, salicylic acid, indole-3-propionic acid, indolebutyric acid, L-tryptophan, phenylacetic acid, 2-oxindole-3-acetic acid, indole-3-acetyl-aspartate or 1 -naphthaleneacetic acid. In certain embodiments, the polymer of the polyamic sodium salt may be free from selective binding to the auxin in the absence of being adsorbed on the SWNT.

[0105] In certain embodiments, the auxin may selectively bind the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM or greater. In certain embodiments, the auxin may selectively bind the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM to about 10.0 pM. In certain embodiments, the selective binding site binds auxin present in vitro or in vivo at a physiological concentration or range of physiological concentrations. In certain embodiments, the auxin may selectively bind the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM, about 0.2 pM, about 0.3 pM, about 0.4 pM, about 0.5 pM, about 0.6 pM, about 0.7 pM, about 0.8 pM, about 0.9 pM, about 1 pM, about 1 .1 pM, about 1 .2 pM, about 1 .3 pM, about 1 .4 pM, about 1 .5 pM, about 1 .6 pM, about 1 .7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 2.9 pM, about 3 pM, about 3.1 pM, about 3.2 pM, about 3.3 pM, about 3.4 pM, about 3.5 pM, about 3.6 pM, about 3.7 pM, about 3.8 pM, about 3.9 pM, about 4 pM, about 4.1 pM, about 4.2 pM, about 4.3 pM, about 4.4 pM, about 4.5 pM, about 4.6 pM, about 4.7 pM, about 4.8 pM, about 4.9 pM, about 5 pM, about 5.1 pM, about 5.2 pM, about 5.3 pM, about 5.4 pM, about 5.5 pM, about 5.6 pM, about 5.7 pM, about 5.8 pM, about 5.9 pM, about 6 pM, about 6.1 pM, about 6.2 pM, about 6.3 pM, about 6.4 pM, about 6.5 pM, about 6.6 pM,about 6.7 pM, about 6.8 pM, about 6.9 pM, about 7 pM, about 7.1 pM, about 7.2 pM, about 7.3 pM, about 7.4 pM, about 7.5 pM, about 7.6 pM, about in pM, about 7.8 pM, about 7.9 pM, about 8 pM, about 8.1 |_iM , about 8.2 pM, about 8.3 pM, about 8.4 pM, about 8.5 pM, about 8.6 pM, about 8.7 pM, about 8.8 pM, about 8.9 pM, about 9 pM, about 9.1 pM, about 9.2 pM, about 9.3 pM, about 9.4 pM, about 9.5 pM, about 9.6 pM, about 9.7 pM, about 9.8 pM, about 9.9 pM, or about 10 pM. In certain embodiments, the auxin may selectively bind the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM to about 5.0 pM.

[0106] In certain embodiments, the compositions may bind an auxin with a specific or estimated binding affinity and / or with a specific or estimated dissociation constant. In certain embodiments, the estimated dissociation constant coefficient (Kd) of the composition to the auxin may be calculated using:wherein p is a proportional factor showing the maximum optical modulation, I is an auxin fluorescence, l0is a normalized fluorescent intensity change before and after addition of I, [6-IAA] is a total number of binding sites, and [0]totai] is a number of occupied binding sites. In certain embodiments, the estimated dissociation constant (Kd) of the composition to the auxin may be between about 1 .0 pM and about 5.0 pM. In certain embodiments the estimated dissociation constant (Kd) of the composition to the auxin may be about 1 pM, about 1.1 pM, about 1.2 pM, about 1.3 pM, about 1.4 pM, about 1.5 pM, about 1.6 pM, about 1.7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 2.9 pM, about 3 pM, about 3.1 pM, about 3.2 pM, about 3.3 pM, about 3.4 pM, about 3.5 pM, about 3.6 pM, about 3.7 pM, about 3.8 pM, about 3.9 pM, about 4 pM, about 4.1 pM, about 4.2 pM, about 4.3 pM, about 4.4 pM, about 4.5 pM, about 4.6 pM, about 4.7 pM, about 4.8 pM, about 4.9 pM, or about 5 pM.

[0107] In certain embodiments, the composition may bind to both IAA and IPA. In certain embodiments, the IAA and the IPA may have different binding parameters to the selective binding site. In certain embodiments, the IPA may bind to the composition faster than IAA. In certain embodiments, the binding of the IAA to the composition may be more thermodynamically favourable than the binding of the IPA to the composition.Methods of forming a composition of the present disclosure

[0108] In certain embodiments, there is provided herein methods of adsorbing a polymer of the polyamic sodium salt of the present disclosure to a single-walled carbon nanotube (SWNT), the method comprising conjugating the polymer of the polyamic sodium salt with the SWNT.

[0109] In certain embodiments, the method may comprise conjugating the polymer of the polyamic sodium salt with the SWNT. The skilled person, in light of the teachings herein, would be able to select an appropriate technique, method or protocol for conjugating the polymer to the SWNT. In certain embodiments, the polymer of the polyamic sodium and the SWNT may be non-covalently conjugated. In certain embodiments, the conjugating may comprise sonication. The skilled person, in light of the specification as a whole, would be able to select appropriate parameters to perform the sonication to conjugate the polymer and SWNT. In certain embodiments, the SWNT may be formed by high-pressure carbon monoxide, as would be known to the skilled person.

[0110] In certain embodiments, the adsorption of the polymer of the polyamic sodium salt to the SWNT may change a wavelength and / or an intensity of fluorescence of the SWNT, as compared to the SWNT without the adsorbed polymer of the polyamic sodium salt.Methods and uses of a composition of the present disclosure

[0111] In certain embodiments, there is provided herein methods of detecting an auxin, the method comprising applying a composition of the present disclosure to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0112] In certain embodiments, there is provided herein methods of detecting an auxin in vivo, the method comprising applying a composition of the present disclosure to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0113] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting an auxin, wherein the detecting comprises: applying the composition to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0114] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting an auxin in vivo, wherein the detecting comprises: applying the composition to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one ormore cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0115] In certain embodiments, the use or method may comprise a step of applying a composition of the present disclosure. In certain embodiments, the step of applying may comprise any technique known to the person of skill that results in uptake of the composition by one or more cells. In certain embodiments, the step of applying may comprise the use of a paintbrush to apply and / or distribute the composition to the one or more cells. In certain embodiments, the step of applying may comprise the use of a pipette or equivalent measuring and distribution tool to apply and distribute the composition to the one or more cells. In certain embodiments, the one or more cells may be incubated in a solution comprising the composition for the step of applying.

[0116] In certain embodiments, the use or method may further comprise measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition. The skilled person, in light of the teachings herein, would be able to select an appropriate technique and / or method for measuring the wavelength and / or intensity of fluorescence of the one or more cells applied with the composition. In certain embodiments, the change in the wavelength and / or intensity is a change in near infrared wavelength and / or intensity of the one or more cells applied with the composition. In certain embodiments, the change in the wavelength and / or intensity of fluorescence of the one or more cells applied with the composition may be a ratiometric signal change. In certain embodiments, the step of measuring may be performed with a nIR camera with an excitation wavelength of about 785 nm and / or laser power of about 30 mW.

[0117] In certain embodiments, the use or method may further comprise a step of determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition. In certain embodiments, the presence or absence of the auxin in the one or more cells applied with the composition may comprise a change in the measured wavelength and / or the measured intensity of fluorescence. In certain embodiments, the presence or absence of the auxin in the one or more cells applied with the composition may comprise a predetermined or calculated measured wavelength and / or the measured intensity of fluorescence of the one or more cells.

[0118] In certain embodiments, the use or method may comprise applying the composition to one or more cells. In certain embodiments, the one or more cells may be one or more cells in an organism. In certain embodiments, the organism may be a plant or a plant seed. In certain embodiments, the one or more cells may be a plant cell or a cell from a plant seed. In certain embodiments, the plant,plant cell, plant seed or plant seed cell may be any plant. In certain embodiments, the plant, plant cell, plant seed or plant seed cell may be from a plant for human or animal consumption, such as for example a fruit or vegetable plant, or for human use, such as for example a cotton or hemp plant. In certain embodiments, the plant, plant cell, plant seed or plant seed cell may be Nicotiana benthamiana, Arabidopsis, choy sum (Brassica chinensis var. parachinensis) , kai Ian, or spinach (Spinacia oleracea). In certain embodiments, the plant, plant cell, plant seed or plant seed cell may be any plant, plant cell, plant seed or plant seed cell wherein a presence, level or distribution of auxin is desired.

[0119] In certain embodiments, the use or method may further comprise a step of measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a sensor or detection composition of the present disclosure. In certain embodiments, the one or more reference cells may be applied with a reference composition. The skilled person, in light of the teachings herein, would be able to select an appropriate reference sensor. In certain embodiments, the measuring of the reference wavelength and / or reference intensity of fluorescence may provide a reference signal, wherein the reference signal provide a background or baseline measure of the wavelength and / or intensity of fluorescence of one or more cells. In certain embodiments, the reference sensor may comprise single-stranded DNA AT15 on CoMoCat™. In certain embodiments, the reference sensor may comprise any sensor desired that does not provide a selective binding site for the auxin, preferably wherein the reference sensor does not provide a selective binding site for any molecule present in the one or more cells.

[0120] In certain embodiments, the use or method may further comprise a step of determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition. In certain embodiments, the reference wavelength may be subtracted from the measured wavelength and / or the reference intensity of fluorescence may be subtracted from the measured wavelength to determine the presence or absence of the auxin in the one or more cells applied with the composition. In certain embodiments, a ratio of the reference wavelength to the measured wavelength and / or a ratio of the reference intensity of fluorescence from the measured wavelength may determine the presence or absence of the auxin in the one or more cells applied with the composition.

[0121] In certain embodiments, there is provided herein, methods of detecting a change in an auxin level and / or a change in an auxin distribution, the method comprising: applying a composition of the present disclosure to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelengthand / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0122] In certain embodiments, the use or method may comprise subtracting the measured first wavelength from the measured second wavelength and / or subtracting the measured first intensity of fluorescence from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition. In certain embodiments, a ratio of the first wavelength to the second wavelength and / or a ratio of the first intensity of fluorescence to the second wavelength may determine the change in the auxin in the one or more cells applied with the composition. In certain embodiments, the change in the auxin in the one or more cells applied with the composition may comprise a predetermined or calculated value determined by subtracting the first and second wavelength and / or first and second intensity of fluorescence or a predetermined or calculated value determined by the ratios of the first and second wavelength and / or intensity of fluorescence.

[0123] In certain embodiments, there is provided herein, a composition of the present disclosure for use in detecting a change in an auxin level and / or a change in an auxin distribution, wherein the detecting comprises: applying the composition to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0124] In certain embodiments, the use or method may comprise measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells after a duration of time and / or a stimulus. In certain embodiments, the duration of time may comprise any duration desired, such as, for example, from less than 1 second to greater than 4 weeks. In certain embodiments, the duration of time may comprise 1 second, 2 second, 3 second, 4 second, 5 second, 6 second, 7 second, 8 second, 9 second, 10 second, 1 1 second, 12 second, 13 second, 14 second, 15 second, 16 second, 17 second, 18 second, 19 second, 20 second, 21 second, 22 second, 23 second, 24 second, 25 second, 26 second, 27 second, 28 second, 29 second, 30 second, 31 second, 32 second, 33 second, 34 second, 35 second, 36 second, 37 second, 38 second, 39 second, 40 second, 41 second, 42 second, 43 second,44 second, 45 second, 46 second, 47 second, 48 second, 49 second, 50 second, 51 second, 52 second,53 second, 54 second, 55 second, 56 second, 57 second, 58 second, 59 second, or 60 second. In certain embodiments, the duration of time may comprise 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 1 1 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, 41 minutes, 42 minutes, 43 minutes, 44 minutes, 45 minutes, 46 minutes, 47 minutes, 48 minutes, 49 minutes, 50 minutes, 51 minutes, 52 minutes, 53 minutes, 54 minutes, 55 minutes, 56 minutes, 57 minutes, 58 minutes, 59 minutes, or 60 minutes. In certain embodiments, the duration of time may comprise 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 1 1 hours, 1 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, or 24 hours. In certain embodiments, the duration of time may comprise 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, or 7 days. In certain embodiments, the duration of time may comprise 1 weeks 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, 10 weeks, 11 weeks, 12 weeks, 13 weeks, 14 weeks, 15 weeks, 16 weeks, 17 weeks, 18 weeks, 19 weeks, 20 weeks, 21 weeks, 22 weeks, 23 weeks, 24 weeks, 25 weeks, 26 weeks, 27 weeks, 28 weeks, 29 weeks, 30 weeks, 31 weeks, 32 weeks, 33 weeks, 34 weeks, 35 weeks, 36 weeks, 37 weeks, 38 weeks, 39 weeks, 40 weeks, 41 weeks, 42 weeks, 43 weeks, 44 weeks, 45 weeks, 46 weeks, 47 weeks, 48 weeks, 49 weeks, 50 weeks, 51 weeks, or 52 weeks. In certain embodiments, the duration of time may comprise 1 year, 2 years, 3 years, 4 years, or 5 years. In certain embodiments, the duration of time may comprise any combination of the above ranges of time, such as, for example a time of 1 year, 46 weeks, 5 days, 1 hours, 57 minutes, 1 seconds or 12 weeks, 1 day, 3 hours, 2 minutes and 6 seconds and so on.

[0125] In certain embodiments, the use or method may comprise measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells after a duration of time and / or a stimulus. In certain embodiments, the stimulus may comprise one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof. In certain embodiments, the stimulus may be any stimulus wherein determining the presence, level or distribution of auxin is desired. In certain embodiments, the stimulus may comprise shade avoidance syndrome, p- estradiol treatment, iaaM expression, a biotic stress, or an abiotic stress. In certain embodiments, the stress may comprise temperature stress, excess light stress, lack of light stress, stress from a pathogen (bacterial, fungal or viral), stress from a pest, excess nutrient stress, lack of nutrient stress, salinity stress, water stress and / or mechanical stress.

[0126] In certain embodiments, the method or use may further comprise measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with a detection or sensor composition of the present disclosure; and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition. In certain embodiments, the use or method may comprise subtracting the measured reference wavelength from the measured first wavelength and the measured second wavelength and / or subtracting the measured reference intensity of fluorescence from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition. In certain embodiments, a ratio of the first wavelength to the second wavelength and / or a ratio of the reference intensity of fluorescence from the first and second wavelength may determine the change in the auxin in the one or more cells applied with the composition. In certain embodiments, the change in the auxin in the one or more cells applied with the composition may comprise a predetermined or calculated value determined by subtracting the reference wavelength from first and second wavelength and / or reference intensity of fluorescence from the first and second intensity of fluorescence or a predetermined or calculated value determined by the ratios of the reference, first and second wavelength and / or intensity of fluorescence.Kits of the present disclosure

[0127] In certain embodiments, there is provided herein, kits for detecting an auxin in vitro or in vivo comprising a composition of the present disclosure and at least one of: instructions for performing a method of the present disclosure; one or more reagent for performing a method of the present disclosure; and one or more buffers. In certain embodiments, the composition may be provided in the kit in a form that is stable for shipping, storage and distribution. In certain embodiments, the kit may be shipped, stored and distributed at or below freezing temperature. In certain embodiments, the kit may be shipped, stored and distributed at or above freezing temperature.Polymers of the present disclosure

[0128] In certain embodiments, there is provided herein, polymers of polyamic sodium salts.In certain embodiments, the polymer of the polyamic sodium salt may comprise one or more of each of an aromatic dianhydride monomer and an aromatic diamine monomer.

[0129] In certain embodiments, the polyamic sodium salt may comprise:wherein n=15-30.

[0130] In certain embodiments, there is provided a method, a process, composition, use, kit, or compound as described herein.

[0131] In certain embodiments, there is an invention as substantially described herein.

[0132] The following examples are provided for illustrative purposes and are intended for the person of skill in the art. These examples are provided to demonstrate certain embodiments as described herein, and should not be seen as limiting in any way.EMBODIMENTS

[0133] In exemplary and non-limiting embodiments, the present disclosure relates to the following:

[0134] (1 ) In an embodiment, a composition comprising: a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin.

[0135] (2) In an embodiment, the composition of (1 ), wherein the polymer of the polyamic sodium salt comprises one or more of each of an aromatic dianhydride monomer and an aromatic diamine monomer.

[0136] (3) In an embodiment, the composition of (1 ) or (2), wherein the polymer of the polyamic sodium salt comprises one or more monomers of each of 4,4'-oxydiphthalic anhydride (OPDA) and 6,6'- diamino-2,2'-bipyridyl (26DAPB).

[0137] (4) In an embodiment, the composition of any one of (1 )-(3), wherein the polymer of the polyamic sodium salt is:, wherein n=15-30.

[0138] (5) In an embodiment, the composition of any one of (1 )-(4), wherein the SWNT is photoluminescent.

[0139] (6) In an embodiment, the composition of any one of (1 )-(5), wherein the SWNT is nearinfrared photoluminescent.

[0140] (7) In an embodiment, the composition of any one of (1 )-(6), wherein a wavelength and / or an intensity of fluorescence of the SWNT in the absence of the adsorbed polymer of the polyamic sodium salt is different from a wavelength and / or an intensity of fluorescence of the SWNT adsorbed with the polymer of the polyamic sodium salt.

[0141] (8) In an embodiment, the composition of any one of (1 )-(7), wherein the polymer of the polyamic sodium salt comprises a wrapping polymer, the wrapping polymer comprising the polymer of the polyamic sodium salt adsorbed to the SWNT in a single-handed helix conformation.

[0142] (9) In an embodiment, the composition of any one of (1 )-(8), wherein the polymer of the polyamic sodium salt is adsorbed to the SWNT at about 50 mg / L to about 200 mg / L.

[0143] (10) In an embodiment, the composition of any one of (1 )-(9), wherein the selective binding site for the auxin comprises a synthetic indole-3-acetic acid (IAA) binding pocket.

[0144] (1 1 ) In an embodiment, the composition of any one of (1)-(10), wherein the selective binding site for the auxin comprises hydrogen bonding and hydrophobic interactions between the auxin and transport inhibitor response 1 (TIR1 ).

[0145] (12) In an embodiment, the composition of any one of (1)-(1 1 ), wherein the selective binding site for the auxin comprises at least one of:(i) a salt-bridge interaction between an indole-3-acetic acid (IAA) carboxyl group and a guanidium residue of arginine 403 of transport inhibitor response 1 (TIR1 ) together with hydrogen bonding of the IAA carboxyl group to another hydroxyl residue of TIR1 serine residue 438;(ii) hydrophobic and van der Waals interaction between an indolic group of the IAA and phenyl residues79 and 82 of the TIR1 ; and(iii) hydrogen bonding between an indolic nitrogen of the IAA and a carbonyl on the side of a TIR1 binding pocket.

[0146] (13) In an embodiment, the composition of any one of (1 )-(12), wherein the selective binding site does not substantially bind to one or more of: gibberellic acid, abscisic acid, jasmonic acid, salicylic acid, indole-3-propionic acid, indolebutyric acid, L-tryptophan, phenylacetic acid, 2-oxindole-3- acetic acid, indole-3-acetyl-aspartate and 1 -naphthaleneacetic acid.

[0147] (14) In an embodiment, the composition of any one of (1 )-(13), wherein the auxin selectively binds the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM or greater.

[0148] (15) In an embodiment, the composition of any one of (1 )-(14), wherein the estimated dissociation constant coefficient (Kd) of the composition to the auxin calculated using:is between about 1.2 pM and about 5.0 pM, wherein p is proportional factor showing the maximum optical modulation, I is an auxin fluorescence, l0is a normalized fluorescent intensity change before and after addition of / , [0 - IAA] is a total number of binding sites, and [0totai] is a number of occupied binding sites.

[0149] (16) In an embodiment, the composition of any one of (1 )-(15), wherein the auxin comprises indole-3-acetic acid (IAA) and / or indole-3-pyruvate (I PA).

[0150] (17) In an embodiment, the composition of any one of (1)-(15), wherein the auxin comprises indole-3-acetic acid (IAA).

[0151] (18) In an embodiment, the composition of (16) or (17), wherein the IAA and the IPA have different binding to the selective binding site.

[0152] (19) In an embodiment, the composition of any one of (1 )-(18), wherein the polymer of the polyamic sodium salt is free from selective binding to the auxin in the absence of being adsorbed on the SWNT.

[0153] (20) In an embodiment, a method of adsorbing the polymer of the polyamic sodium salt as defined in any one of (1 )-(19) to a single-walled carbon nanotube (SWNT), the method comprising conjugating the polymer of the polyamic sodium salt with the SWNT.

[0154] (21 ) In an embodiment, the method of (20), wherein the polymer of the polyamic sodium and the SWNT are non-covalently conjugated.

[0155] (22) In an embodiment, the method of (20) or (21 ), wherein the conjugating comprises sonication.

[0156] (23) In an embodiment, the method of any one of (20)-(22), further comprising a step of forming the SWNT with high-pressure carbon monoxide.

[0157] (24) In an embodiment, the method of any one of (20) -(23) , wherein the adsorption of the polymer of the polyamic sodium salt to the SWNT changes a wavelength and / or an intensity of fluorescence of the SWNT.

[0158] (25) In an embodiment, a method of detecting an auxin, the method comprising: applying the composition of any one of (1 )-(19) to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0159] (26) In an embodiment, a method of detecting an auxin in vivo, the method comprising: applying the composition of any one of (1 )-(19) to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0160] (27) In an embodiment, the method of (26), wherein the organism is a plant or a plant seed.

[0161] (28) In an embodiment, the method of (26) or (27), wherein the organism is selected from the group consisting of Nicotiana benthamiana, an Arabidopsis, choy sum (Brassica chinensis var. parachinensis), kai Ian, and spinach (Spinacia oleracea).

[0162] (29) In an embodiment, the method of any one of (25)-(28), further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of (1 )-(19); and determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0163] (30) In an embodiment, the method of (29), wherein the measured reference wavelength is subtracted from the measured wavelength and / or the measured reference intensity of fluorescence is subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.

[0164] (31 ) In an embodiment, a method of detecting a change in an auxin level and / or a change in an auxin distribution, the method comprising: applying the composition of any one of (1 )-(19) to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0165] (32) In an embodiment, the method of (31 ), wherein the measured first wavelength is subtracted from the measured second wavelength and / or the measured first intensity of fluorescence is subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0166] (33) In an embodiment, the method of (31 ) or (32), wherein the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells comprises a measurement after a duration of time and / or a stimulus.

[0167] (34) In an embodiment, the method of (33), wherein the stimulus comprising one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

[0168] (35) In an embodiment, the method of any one of (31 )-(34), further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of (1 )-(19); and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0169] (36) In an embodiment, the method of (35), wherein the measured reference wavelength is subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence is subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0170] (37) In an embodiment, a kit for detecting an auxin in vivo comprising the composition of any one of (1 )-(19) and at least one of: instructions for performing the method of any one of (25)-(36); one or more reagent for performing the method of any one of (25)-(36); and one or more buffers.

[0171] (38) In an embodiment, the composition of any one of (1 )-(19) for use in detecting an auxin, wherein the detecting comprises: applying the composition to one or more cells;measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0172] (39) In an embodiment, the composition of any one of (1 )-(19) for use in detecting an auxin in vivo, wherein the detecting comprises: applying the composition to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

[0173] (40) In an embodiment, the composition for use of (39), wherein the organism is a plant or a plant seed.

[0174] (41 ) In an embodiment, the composition for use of (39) or (40), wherein the organism is selected from the group consisting of Nicotiana benthamiana, an Arabidopsis, choy sum (Brassica chinensis var. parachinensis), kai Ian, and spinach (Spinacia oleracea).

[0175] (42) In an embodiment, the composition for use of any one of (38)-(41 ), further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of (1 )-(19); and determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

[0176] (43) In an embodiment, the composition for use of (42), wherein the measured reference wavelength is subtracted from the measured wavelength and / or the measured reference intensity of fluorescence is subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.

[0177] (44) In an embodiment, the composition of any one of (1 )-(19) for use in detecting a change in an auxin level and / or a change in an auxin distribution, wherein the detecting comprises: applying the composition to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0178] (45) In an embodiment, the composition for use of (44), wherein the measured first wavelength is subtracted from the measured second wavelength and / or the measured first intensity of fluorescence is subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0179] (46) In an embodiment, the composition for use of (44) or (45), wherein the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells comprises a measurement after a duration of time and / or a stimulus.

[0180] (47) In an embodiment, the composition for use of (46), wherein the stimulus comprising one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

[0181] (48) In an embodiment, the composition for use of any one of (44)-(47), further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of (1 )-(19); and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0182] (49) In an embodiment, the composition for use of (48), wherein the measured reference wavelength is subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence is subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

[0183] (50) In an embodiment, a polymer of a polyamic sodium salt, wherein the polymer is:, wherein n=15-30.

[0184] (51 ) In an embodiment, a method, process, composition, use, kit, pharmaceutical composition, or compound as substantially described herein.

[0185] (52) In an embodiment, the invention as substantially described herein.EXAMPLES

[0186] Example 1 - ResultsDesign of IAA nanosensor by taking cues from the IAA interaction with TRANSPORT INHIBITOR RESPONSE1 (TIR1)

[0187] Although IAA is a key phytohormone for regulating plant growth and stress response, quantification of IAA content in plant tissues requires sample homogenization and long experimental procedures. Fluorescent auxin reporters, which are typically used to study auxin distribution in plant roots, are also unsuitable for measuring IAA in the above-ground plant tissues due to interference from chlorophyll autofluorescence. As such, the present disclosure sought to develop an IAA sensor that emits nIR fluorescence, which allows for direct and real-time measurement of IAA in the leaf, thereby allowing for easy monitoring of plant stress in agriculture.

[0188] The IAA nanosensor was developed based on the CoPhMoRe platform that has been described previously34. This approach involves the physical adsorption of a synthetic polymer on single wall carbon nanotube (SWNT) surface, creating an aqueous corona phase that allows for selective docking of the IAA analyte. The synthetic corona phase for IAA sensing was designed, screened, and optimized from a compositionally varied library of synthetic polymers. By employing carbon nanotube as the signal transducer, the sensor offers highly photostable bandgap nIR fluorescence with wavelengths that are often non-interfering with photo-absorption or autofluorescence windows of living tissue31. The design for IAA sensing was inspired from the known interactions between IAA and the TIR33TIR1 is an F-box protein subunit of the ubiquitin ligase complex (SCFTIR1) that is primarily involved in auxin-mediated signaling pathways35’36. Crystallographic study on the TIR1 -IAA complex reveals several key binding modes, including: (i) the salt-bridge interaction between IAA carboxyl group and a guanidium residue (Arg 403) of TIR1 , coupled with a hydrogen bonding of IAA carboxyl group to another hydroxyl residue of TIR1 serine building block (Ser 438), (ii) the hydrophobic and van der Waals interaction between IAA indolic group and phenyl residues (Phe 79 and Phe 82) on TIR1 , and (iii) the hydrogen bonding between indolic nitrogen of IAA and a carbonyl on the side of TIR1 binding pocket32(Fig. 1 a). To capture the interactions between hydrophilic and hydrophobic portions of IAA, the use of synthetic amphiphilic polyamic sodium salts with tunable functional groups was proposed as the backbone of corona phase construct.Synthesis of CoPhMoRes library for IAA nanosensor screening

[0189] In general, polyamic acid sodium salts are neutralized water-soluble derivations of polyamic acids, which are a type of co-polymer system formed by condensation reaction between an aromatic dianhydride and aromatic diamine. The backbone of these polymers is rich with phenylmoieties which is known for TT-TT stacking on the nanotube surface37, assisting the formation of stable aqueous corona phase for potential IAA docking. It also has a high density of amide bonds, carboxylate / carboxylic groups and pyridine nitrogen-based functional groups which can be modified for preferential hydrogen bonding and ionic interactions with the corresponding functional group in IAA (Fig. 1 a). Based on the corresponding list of synthesized polyamic acids sodium salts (Fig. 7, 8), a library of 20 CoPhMoRe-based sensors for IAA sensing was generated, through non-covalent conjugation with SWNTs using the tip-sonication method34. Characterization of these CoPhMoRes with UV-Vis-nIR spectroscopy showed well-defined absorption chirality peaks in the Sn and S22 regions, indicating that these polymers wrap non-selectively to all SWNT chiralities with suspension yields up to 50-200 mg L’1(Fig. 9).Screening of nanosensor candidates against IAA and other phytohormones

[0190] Screening was carried out using photoluminescence spectroscopy to investigate the nIR optical modulation of each CoPhMoRe sensor against IAA and other phytohormones. The evaluation of optical modulation is based on the normalized fluorescence intensity changes, (l-l0) / l0, before (l0) and after (I) analyte addition. A false color-coded heatmap in Fig. 1 b summarizes the optical response of the 20 CoPhMoRe sensors against IAA and other phytohormones (e.g., GA3, ABA, JA, SA). It was observed that CoPhMoRe sensor #3, made from two monomers (OPDA and 26DAPB), selectively and strongly responded to 100 pM IAA with 75% fluorescence quenching while being insensitive to other analytes (Fig. 1 b). While other sensors (sensor #10, #12, and #20) showed strong response to IAA, they clearly reacted to other plant hormones (Fig. 1 b). As plant samples are heterogenous that simultaneously contain these confounding analytes, these sensors were excluded from further testing as an lAA-specific nanosensor. The remaining CoPhMoRe sensors were not selected because of weak response to IAA (Fig. 1 b). Other CoPhMoRe sensors were not selected because of weak response or low specificity to IAA (Fig. 1 b). In addition, both IAA in deprotonated (neutralized by NaOH) and protonated (diluted in DMSO) forms responded well to CoPhMoRe #3 with 75% and 52% quenching, respectively (Fig. 1 c). The weaker quenching response in protonated form may be due to competitive binding by DMSO (Fig. 1 c). The IAA nanosensor maintained consistent quenching to deprotonated IAA across different pH levels and ionic strength (Fig. 1 c), suggesting that binding between IAA and the nanosensor is primarily driven by the indole group of IAA, as the carboxyl group of IAA may undergo protonation change. It was also found no change in the absorption intensity of the nanosensor before and after adding either form of IAA (Fig. 10), thereby ruling out a possible direct charge transfer interaction between IAA and SWNT38^0. Additionally, the lack of a clear correlation between SWNT chiralities and their optical responses to IAA (Fig. 1 1 ) and the reversible binding nature (as demonstrated later in Fig. 1 g) suggest that fluorescence modulation during IAA binding primarily involves conformational changes of thepolymer that affect exciton decay pathways41’42. While the nanosensor can measure both forms of IAA, it is important to note that IAA mostly exists as the deprotonated form in the cytosol due to its relative alkalinity43.

[0191] As the present CoPhMoRe library consists of polyamic polymers, they likely adopt similar conformations when wrapped on SWNTs. As such, the selectivity and binding sensitivity of the corona phase are probably determined by the surface coverage and chemical structure of the polymer. To elucidate this, corona surface coverage was correlated with the selectivity and sensitivity of each CoPhMoRe sensor against various plant hormones (Fig. 12). Surface coverage was determined by Molecular Probe Adsorption assay44, which gives a surface coverage parameter q / K0where q is the number of accessible sites for analytes binding and Kois the dissociation constant of the molecular probe with the corona phase. Here, a lower q / Kdvalue indicates tighter corona binding with higher surface coverage. The present analysis showed that only corona phases from 26DABP series demonstrated variable response to IAA, with the strongest fluorescence quenching observed for q / Kdvalues between 350-450 M'1(Fig. 12, CoPhMoRe #3 and CoPhMoRe #20). On the other hand, fluorescent responses of all CoPhMoRes tested, whose surface coverage q / Kcrange from 300 to 1000 M’1, are largely invariant to GA, JA, ABA, and SA, regardless of the diversity of polymer chemical structures. These observations suggest an optimal “sweet spot” for sensitivity and selectivity of IAA sensing, which is contributed by both surface coverage and the specific diamine moiety on the polymer backbone (Fig. 12).In vitro investigation of IAA nanosensor

[0192] For further investigation on its selectivity and specificity, the sensor responses were measured against a wide range of potential interfering analytes at 100 pM concentration, including auxin homologs, auxin-related metabolites and other relevant plant signaling molecules (Fig. 1d, red columns). The results showed that IAA sensor was relatively inert in the presence of those analytes except for IPA, which showed a 33% increase in fluorescence intensity (Fig. 1d). However, further addition of 10 pM IAA resulted in 25% quenching of the sensor fluorescence (Fig. 1 d, cyan columns). In general, the interaction between IAA and the sensor was still preferential compared to other IAA- related analytes, as the sensor displayed approximately 50% fluorescence quenching in solutions containing 10 pM IAA and 100 pM of potential interfering analytes (Fig. 1 d, cyan columns).

[0193] To investigate the binding dynamics between IPA and IAA, a fluorescence kinetic study was conducted. The results, shown in Fig. 13, revealed that upon the addition of IPA, the fluorescence intensity increased, but quickly transitioned to a quenched state in the presence of both IPA and IAA at10:1 molar ratio. This indicates that while IPA binds to the sensor rapidly, IAA binding is thermodynamically favored, resulting in the sensor to show quenched fluorescence at equilibrium.In vitro calibration and reversibility of an IAA nanosensor

[0194] The excitation-emission heatmap of IAA nanosensor in response to 100 pM IAA demonstrated that all observed SWNT chiralities underwent fluorescence quenching upon IAA addition (Fig. 1 e). This suggests that IAA does not exhibit any preferential interaction with SWNT chirality. A calibration curve for the IAA sensor was generated in vitro, with IAA concentrations ranging from 0.01 to 100 pM, and showed that the sensor could detect IAA at concentrations as low as 0.1 pM (Fig. 1 f). This is within the range of in planta detection, as the average endogenous IAA concentration in Arabidopsis has been reported to be approximately 10-250 pg mg-1fresh weight (which converts to 0.1 - 1 .8 pM, assuming that water contributes to 80% of the fresh weight)45. The dissociation constant coefficient Kd, which measures the binding affinity of IAA to the sensor, was estimated using Langmuir adsorption isotherm model:

[0195] Where / 3 is proportional factor showing the maximum optical modulation, [0 - IAA] and [^totai] are the concentration of occupied and total binding sites respectively. By fitting the experimental data into equation (1 ), the general Kdwas estimated to be 4.5±0.21 pM. Estimation of specific Kdand / 3 values for each SWNT chirality showed a slight dependence on chirality type to IAA affinity (Fig. 1 1). SWNT chirality (10,2) seems to have least affinity to IAA with dissociation constant Ka= 4.33 ± 0.51 pM while the other three, (7,6), (7,5) and (8,4), have higher affinities with K„ > 1 .2-1 .5 pM. The data suggests that using chirality-separated SWNTs such as (7,6) could potentially yield more refined fluorescent modulation (by exclusion of less responsive chirality) and better overall photoluminescent intensity comparing from multi-chiral SWNT mixtures46.

[0196] The reversibility of the IAA sensor was confirmed through monitoring its response to in situ photodegradation of IAA. IAA is photolabile and can be oxidized into OxlAA when exposed to low- wavelength high-intensity light47. UV-Vis spectroscopy showed a gradual degradation of IAA when exposed to a 600 nm light source (Fig. 14). Continuous monitoring of fluorescence intensity of the sensor showed that the addition of 5 pM IAA initially resulted in fluorescence quenching, but gradually recovered upon prolonged excitation, indicating in situ photodegradation of IAA to OxlAA (Fig. 1 g). Similar observations were made upon repeated additions of 5 pM IAA to the same sample (Fig. 1 g). This result indicates that the binding between IAA and its sensor is reversible, and the kinetic response is on a similar time scale as the rate of IAA photodegradation (Fig. 14).IAA nanosensor localized inside leaf cells upon infiltration

[0197] For accurate interpretation of the IAA nanosensor signal in planta, determination of its localization in the plant tissue is needed. While IAA is biosynthesized in the cytoplasm, it may be transported to the nucleus for regulating auxin-responsive genes, conjugated and catabolized in the endoplasmic reticulum, or sequestered in the vacuole to regulate available IAA in plant cell48’49. Furthermore, IAA also undergoes intercellular transport to establish auxin gradients along plant tissues50. Although numerous transgenic biosensors have successfully demonstrated IAA detection inside roots, the present study is focused on IAA detection in leaf tissues. IAA is readily synthesized in the leaf and regulates growth, development, and stress response9. However, existing fluorescent biosensors have limited application in the leaves due to chlorophyll autofluorescence51 52.

[0198] To investigate the SWNT-based IAA nanosensor in planta, the sensor was administered into leaf tissues through the abaxial epidermis using a needleless syringe. Infiltration of nanosensors by this technique did not affect plant growth or physiology, as there was no visible damage to leaf tissues nor reduction of chlorophyll content in leaves infiltrated with the nanosensor (Fig. 15). The design of the IAA nanosensor took into account of its size and zeta potential to enable spontaneous transport through the cell wall and lipid membrane, as described in the LEEP theory53. To investigate the localization of the IAA nanosensor after infiltration into leaf tissues, a confocal Raman spectroscopy system was used to precisely detect the SWNT-specific Raman G-band at the cellular level. In vitro Raman measurement of the IAA nanosensor verified that it produces a strong Raman G-band at 1590 cm1Raman shift (Fig. 2a). Using Arabidopsis leaves infiltrated with the IAA nanosensor, the Raman spectra of distinct cells in the transverse cross-section and abaxial epidermal surface of the leaf were measured (Fig. 2b). Interestingly, it was found that the IAA nanosensor did not localize equally to the various cells of the leaf tissue. The IAA sensor Raman peak showed the highest intensity in the spongy mesophyll cells, followed by the palisade mesophyll cells (Fig. 2c). In contrast, the air space and epidermal cells, such as guard cells and pavement cells displayed relatively low sensor Raman peak intensity (Fig. 2c). This suggests that, although the IAA nanosensor was infiltrated through the abaxial leaf surface, the sensors selectively localized to the mesophyll cells.

[0199] To elucidate whether the IAA nanosensors entered the leaf cells or retained on their cell surface after infiltration, protoplasts from leaf tissues with and without IAA nanosensor infiltration were isolated. Protoplasts isolated from both samples were visually similar, suggesting that the IAA nanosensor did not adversely affect the cells (Fig. 2d). Confocal Raman spectroscopy at the center of these protoplasts revealed that the sensor-specific Raman peak was found only in protoplasts isolated from leaf tissue infiltrated with the IAA nanosensor (Fig. 2e). This implies that the IAA nanosensors localized inside the Arabidopsis leaf cells after infiltration. To further investigate if the IAA nanosensorspecifically localized to the center of protoplasts, Raman spectroscopy measurements along the plasma membrane, as well as a nearby area containing only the buffer, were performed (Fig. 16a). The sensorspecific Raman peak was detected only at the center of the protoplasts. In contrast, the Raman spectra along the plasma membrane (up, down, left, right, Fig. 16b) comprised of strong carotenoid Raman peaks that corresponded to the abundance of chloroplasts, but no detectable sensor Raman peak (Fig. 16b). Furthermore, the Raman spectra at different focal planes were measured to ascertain if the IAA nanosensor is found inside the protoplast (Fig. 2f). While the sensor-specific Raman peak showed the highest peak intensity at the center focal plane, shifting the focal plane towards the protoplast surface resulted in progressively weaker sensor Raman peak intensity (Fig. 2g). These suggest that the IAA nanosensor was found inside the protoplasts and not on the cell surface.

[0200] The IAA nanosensor localization inside leaf cells was further confirmed using Nicotiana benthamiana. Similar to Arabidopsis, the sensor Raman peak intensity was strongest in the spongy mesophyll cells of N. benthamiana leaf tissue (Fig. 17a-b). In contrast, other cell types and the air space displayed much weaker sensor Raman peaks (Fig. 17a-b). Likewise, the sensor Raman peak was detected in protoplasts isolated from N. benthamiana leaf samples infiltrated with the IAA sensor (Fig. 17c-d). In contrast, leaves without sensor infiltration did not produce any protoplast with the sensor Raman peak (Fig. 17c-d). The highly similar results between Arabidopsis and N. benthamiana indicate that the IAA sensor localized inside leaf cells upon infiltration.

[0201] The ability of the IAA nanosensor to localize within isolated N. benthamiana protoplasts was further supported by the present hyperspectral study (Fig. 2h-j). After 1 hour incubation of the IAA sensor with the isolated protoplasts, localization of the IAA nanosensor nIR fluorescence signals within the protoplast was observed (Fig. 2h). After deconvoluting the total fluorescence into each chirality, it was observed that all sensor chiralities show similar uptake into the protoplast (Fig. 2i). It was further proved that strong nIR fluorescence signals within the protoplast derive from the IAA nanosensor, as seen from the signature SWNT fluorescence spectra (Fig. 2j). The spectra derived from pixels elsewhere (outside and inside the protoplast) can be partly attributed to the scattering of SWNT emissions, which caused these non-SWNT locations to show weak fluorescence (Fig. 2j). Regardless, spectra from within the protoplasts (inside) show higher intensity than the spectra of the buffer (outside), indicating an overall uptake of the IAA nanosensor into the cell (Fig. 2j).IAA nanosensor allows for quantification of IAA levels in Arabidopsis plant

[0202] The in vitro investigation has showed that IAA nanosensor could exhibit dose-dependent quenching response to IAA. To validate and study the sensor response in planta, a transgenic Arabidopsis plant expressing XVE::iaaM was developed, which uses a p-estradiol inducible geneexpression system to control endogenous IAA levels54. XVE::iaaM Arabidopsis plants were screened and an optimal transgenic line was selected to have low basal expression of iaaM, but strong and proportional induction of iaaM expression when exposed to p-estradiol (Fig. 18). Topical application of p-estradiol on the leaf resulted in leaf curling and hyponasty, which are indicative of an increase in endogenous IAA and auxin activity (Fig. 3a, 19a-b). The induction of iaaM gene expression, auxin- responsive GH3.3 gene expression, and endogenous IAA level at 24 h post-treatment were verified upon treatment with p-estradiol inducer (Fig. 3b).

[0203] While the techniques described above elucidated IAA content and the corresponding auxin activity at specific time points, use of the IAA nanosensor in planta would enable real-time analysis of auxin dynamics upon treatment with p-estradiol. In this work, a ratiometric platform5’46consisting of IAA nanosensor and an inert reference nanosensor, (AT)i5-SWNT, was utilized for in vivo detection of endogenous IAA (Fig. 3c). The inventors' previous work demonstrates how such nanosensors can be utilized ratiometrically46. (AT)I5-SWNT is a nano-conjugate formed from the wrapping of single-strand DNA (AT)I5on the nanotube surface. This inert sensor gives invariant optical response to IAA and other relevant plant analytes (Fig. 20). The use of a reference sensor improves the confidence of attributing the IAA nanosensor response to the presence of IAA in a complex in vivo medium (i.e. within the leaf tissue). In addition, the ratiometric response, calculated as the ratio of IAA nanosensor fluorescence intensity to the average intensity of reference sensor, would improve the signal-to-noise ratio and provide a more accurate evaluation of IAA concentration. This is because any fluctuation in fluorescence signal due to external factors, such as laser power fluctuations or background lighting, would be reflected by the reference sensor response, which can then be corrected by ratiometric analysis.

[0204] By using a needleless syringe, the IAA nanosensor and reference nanosensor were infiltrated into two adjacent regions of the XVE::iaaM rosette leaf lamina, separated by the midrib (Fig. 3c). The nIR fluorescence of both nanosensors was monitored under constant excitation at a standoff distance of 1 m using a 2D array InGaAs detector equipped with a 900 nm long-pass filter. To ensure that plant health is not affected by constant exposure to the excitation laser, the total chlorophyll content of leaf samples was assessed and no significant change was found even after prolonged laser exposure (Fig. 21 ). The use of a standoff detection setup enables remote sensing with an expanded field of view, facilitating the study of whole-plant physiology with minimal sample handling. After 6 h topical treatment of 100 pM p-estradiol on the adaxial surface, fluorescence intensity of the IAA nanosensor and reference sensor were captured continuously for 16 h. False-color nIR images of the leaf sample at different time points showed increasingly potent systematic fluorescent quenching of the IAA nanosensor, from 6 to 10 h post-treatment of p-estradiol, followed by a gradual return towards the baseline from 10 h onwards (Fig. 3c-d). On the other hand, the fluorescence intensity of reference sensor (AT)I5-SWNT remainedrelatively constant throughout the experiment (Fig. 3c-d). The significant quenching observed by the IAA nanosensor indicated an increase of IAA content, which aligned with the result from biochemical assays (Fig. 3b). To quantitatively assess the change in IAA levels induced by p-estradiol, the ratiometric response of IAA nanosensor was correlated to IAA concentration using a reversible first-order binding model for the IAA nanosensor (see Methods Section for model development). In this model, the normalized fluorescence intensity l / l0was utilized, which was calculated by using the average intensity of the first 100 scans as the baseline (l0). As such, the derived result should be interpreted as the change of auxin level compared to the initial time point before induction. By extracting the ratiometric response from each pixel and applying it to the model, 2D images of auxin distribution level from the corresponding original nIR images were generated (Fig. 3e). These images showed a substantial increase in IAA level from 6 to 22 h after treatment, with the increase being uniform across the lamina separated by the secondary veins (Fig. 3e). Fig. 3d and 3f summarize the average time-profile response of the reference nanosensor, the IAA nanosensor, its ratiometric value, and corresponding calculated changes in IAA level; showing that chemically induced IAA biosynthesis peaks at around 13 h after treatment, followed by a gradual decrease. The reduction in IAA concentration after the peak could be attributed to IAA metabolism in response to excess IAA production, as evidenced by the increased expression of GH3.3 (Fig. 3b). The original data of nanosensor responses in figures 3d is shown in Fig. 29.

[0205] The nanosensor also demonstrated a dose-dependent response to p-estradiol. XVE::iaaM Arabidopsis leaves treated with 0 pM (mock), 10, 25, and 100 pM of p-estradiol resulted in the IAA nanosensor to show transient modulations in intensity, which were relatively proportional to the amount of p-estradiol applied (Fig. 3g). Increasing p-estradiol concentrations result in an approximate exponential decrease in ratiometric response of the IAA nanosensor (Fig. 22). The non-linearity of the response may be attributed to several factors such as the saturation of p-estradiol in stimulating IAA biosynthesis. The mock treatment resulted in a constant ratiometric intensity, while higher concentrations of p-estradiol caused greater signal quenching (Fig. 3g-h). This highlights the sensitivity of the present IAA nanosensor in measuring transient changes to IAA levels.Detection of local IAA movement in XVE::iaaM Arabidopsis plants using IAA nanosensor

[0206] Spatiotemporal distribution of auxin is a key factor in regulating plant growth and development5556. By using XVE::iaaM Arabidopsis plants, the IAA nanosensor is able to track the transport of chemically-induced IAA. While the previous experiment applied the p-estradiol inducer to the entire leaf to cause a global increase in IAA levels, topical application of the inducer at a small, specific spot on the leaf would give rise to a localized increase in IAA levels, which is useful for demonstrating auxin movement. Spot application of the inducer on one side of the leaf triggered leaf curling only on the treated side and hyponasty, indicating a localized increase in IAA concentrations(Fig. 4a, 19c). Similar to the previous experiment, the localized induction of iaaM and subsequent IAA accumulation was verified by gene expression of iaaM and GH3.3 (Fig. 4a-c). iaaM expression was greatly induced at the treated spot, while expression in the treated side and the untreated side of the leaf remained low (Fig. 4c). However, while the expression of auxin-responsive gene GH3.3 was strongly induced at the treated spot compared to the untreated side (132-fold increase, Fig. 4c), the treated side also showed a significant but milder induction (31 -fold increase, Fig. 4c). This suggests that the high expression of iaaM greatly induced local IAA synthesis at the treated spot, which was likely transported out to surrounding areas in the treated side of the leaf, but barely passed through the midvein to the untreated side.

[0207] Likewise, application of the IAA nanosensor revealed significant nIR fluorescence quenching at the treated spot, which gradually expanded to the treated side over time (Fig. 4d-e). Image analysis showed a rapid increase in IAA level at the treated spot from 6 h post-treatment, which peaked at 14 h post-treatment, followed by a gradual decrease from 14 to 18 h post-treatment (Fig. 4d-f). In contrast, IAA levels in the surrounding areas on the treated side displayed a gradual increase, while the untreated side exhibited no significant change (Fig. 4d-f). Average time-profile curves were generated to visualize the IAA levels at the treated spot (T) and surrounding regions of interest (A, B, C, D; Fig. 4b, f), which clearly demonstrated IAA concentrations gradually increasing in the surrounding areas from 6 to 12 h after treatment. This indicates that IAA biosynthesis was induced at the treated spot, then transported to the surrounding cells and tissues. At the same time, IAA level was unchanged on the untreated side (U, Fig. 4f), which is consistent with auxin-responsive gene expression (Fig. 4c, GH3.3 on the untreated side) and a previous study that showed the midvein acting as a boundary for auxin response57.

[0208] To further probe the spatial distribution and transport of IAA, a one-dimensional steadystate reaction-diffusion model was developed to describe the spatial IAA concentration data in Fig. 4d- e at each time point. Specifically, the concentration profile from the midvein (x - 0) to the margin of the leaf (x = 1) was analyzed (Fig. 4g). In this model, IAA is generated with rate y across the inducer-treated spot with its distribution modeled by a Gaussian function centered about point a with standard deviation o. IAA is free to diffuse within the leaf but is also inactivated and consumed throughout the leaf. A Damkohler numberwas defined to describe the relative rates of IAA reaction and diffusion. At the midvein, a no-flux boundary condition was employed, as IAA was shown to be unable to cross the midvein by the data (Fig. 4c-f) and a previous study57. As for the leaf margin boundary, it was considered that auxin response has previously been shown to accumulate at the leaf margins under shade conditions57. It has been suggested that auxin transport proteins are localized along the cells to form a canal of auxin flow from source to the sink58. Thus, a convective boundary condition between the IAAconcentration in the leaf blade and the bulk IAA concentration in the leaf margins with mass transfer coefficient kmarginwas employed. The non-dimensionalized mass balance for IAA can be written as follows (see Supplementary Information for details):with boundary conditions(3)(4)

[0209] C is the dimensionless concentration of IAA and x is a dimensionless length scale. For fitting to the data, a small region approximately centered about the induced spot as a representative region was chosen to be analyzed (Fig. 4g). Data close to the edges of the sensor spot were neglected due to artifacts. The model parameters a, y, <p, and kmarginwere fit to the experimental data at each time point (Fig. 4h). The results for each highlighted time point in Fig. 4g are summarized in Table 1. d and y are shape parameters reflecting the production magnitude and spread of IAA around the inducer- treated spot.

[0210] Table 1. Model Fitting Parameters

[0211] Interestingly, < / >2appears to be relatively consistent across the different time points. Physically, <p2» 1 corresponds to IAA that is rapidly consumed and cannot diffuse far across the leaf, whereas <j>2« 1 corresponds to IAA that is free to travel far across the leaf without being reacted away. Here, it was found 1, which corresponds well with the data in Fig. 4d-f. IAA slowly spreads across the leaf, reflected by the gradually increasing concentration profiles at the analyzed spots (A, B, C, D; Fig. 4b, f). However, the IAA concentrations at the analyzed spots never equalize with the concentration at the treated spot (T; Fig. 4b, f), indicating rapid degradation. In this model, the Damkohler number isa ratio of two length scales: <p2= Q) , where A = 0.14 cm is the length of the reaction zone (see Methods Section for details). According to the model, IAA can diffuse slightly under one-third the length of the treated half of the leaf before it is fully consumed.

[0212] ^margin is highest at the first time point (6 h), but then drops off in the later time points. This suggests that although the margin concentration may be negligible initially, it may begin to “fill” with IAA, reducing the driving force for mass transfer. Notably, the model is insensitive to kmarg inat the later time points (t > 9 h), suggesting that the IAA concentration in the margin may be saturated by the IAA produced in the blade of the leaf, resulting in a boundary condition resembling no flux, like the midvein boundary condition. This can be seen in the behavior of the model solutions for later time points (Fig. 4h, t > 9). This analysis is able to describe the IAA concentration maximum as between the mid-rib and leaf margin, and therefore supports the observation of a no flux boundary condition at the former location.IAA nanosensor can monitor IAA changes under shade stress

[0213] It was further questioned if the IAA nanosensor can be applied to measure natural changes in endogenous IAA that are caused by plant response to stress. A common abiotic stress for plant growth is shade avoidance syndrome (SAS), during which shade exposure transiently induces IAA biosynthesis and increases IAA content59. Under shade, plants up-regulate auxin biosynthesis in the leaves and initiate auxin transport from the leaves towards the shoot, which alters the spatial and temporal distribution of auxin57. This eventually results in shoot elongation and leaf hyponasty as an adaptive response to increase photosynthesis6061.

[0214] The ability of IAA nanosensor in measuring basal levels of endogenous IAA was firstly verified through the use of IAA biosynthesis inhibitors, Yucasin and L-Kynurenine62. In this experiment, the IAA nanosensor is infiltrated throughout the N. benthamiana leaf, followed by topical application of IAA biosynthesis inhibitors on one side of the leaf, while a mock treatment was applied to the other side (Fig. 23). It was hypothesized that the IAA biosynthesis inhibitors will inhibit basal biosynthesis of IAA, thereby reducing IAA content, and resulting in higher IAA nanosensor fluorescence (less quenching). The nIR images supported the hypothesis, as it showed the IAA biosynthesis inhibitors increased sensor fluorescence, compared to the mock treatment (Fig. 23a). This was further verified by nIR image analysis of normalized sensor intensities, as the normalized pixel intensities (l / l0) on the inhibitor-treated side were higher than those on the mock-treated side from 3 h post-treatment onwards (Fig. 23b), indicating a decrease in IAA level on the side treated with the inhibitor. Furthermore, the normalized pixel intensities steadily rose with prolonged inhibitor treatment (Fig. 23b), highlighting their potency inlowering IAA content. This experiment confirmed the sensitivity of the disclosed IAA nanosensor in detecting basal IAA levels in planta, suggesting that it can be utilized to monitor changes in IAA levels.

[0215] To investigate transient changes of IAA levels during shade stress, the sensor was employed in N. benthamiana leaf subjected to shade condition, which comprised of reduced light intensity and low Red:Far-red ratio (R:FR) (Fig. 5a). Continuous nIR imaging over 6 h revealed an overall quenching of the IAA nanosensor, which reached a local minimum at 3 h shade before returning to the baseline (Fig. 5b-c). In contrast, the reference sensor showed an invariant response throughout the whole process (Fig. 5b-c). The average ratiometric intensity and the calculated auxin level showed a waveform-like response, with IAA level increasing shortly after exposure to shade, reaching a maximum at 3 h, then declining towards baseline levels afterwards (Fig. 5c, e-f). The original data of nanosensor responses in figures 5c is shown in Fig. 29. The initial increase in IAA levels was likely due to increased IAA biosynthesis during SAS, while the subsequent decline may be attributed to the transport of IAA from the lamina to the stem, where elongation occurs14. The pattern of IAA level derived from the sensor corroborated well with IAA levels determined independently by liquid chromatographymass spectrometry (LC-MS), as both results show IAA levels increasing under shade, peaking at 3 h, then decreasing towards baseline levels afterwards (Fig. 5d). Conversely, in the control setup where plants were exposed to normal light condition, both IAA sensor and reference sensor showed no significant change in fluorescence (Fig. 24), which also matched the results obtained by LC-MS (Fig. 5d).

[0216] To further probe the spatiotemporal changes to IAA levels under shade, the IAA nanosensor was applied to a larger area of the leaf for clearer observation (Fig. 5g). Similar to Fig. 5b, the sensor reported a transient induction of IAA level under shade (Fig. 5h). Image analysis for spatial and temporal distribution of IAA, derived from the nIR fluorescent intensity changes, revealed that IAA levels increased shortly upon shade treatment and reached a maximum at 3 h shade (Fig. 5h). IAA mostly accumulated near the leaf tip region from 1 .5 to 3 h shade (Fig. 5h). Afterwards, IAA level near the leaf tip decreased as IAA was transported towards the base (Fig. 5h). To support the observation from the IAA nanosensor, different parts of the N. benthamiana leaf under shade were sampled to measure IAA levels by LC-MS (Fig. 5i-j). All parts of the leaf showed elevated IAA levels during shade treatment, which peaked at 3 h shade (Fig. 5i). While the IAA content in the leaf tip and side regions reduced by almost half at 6 h shade, the base region retained a relatively high IAA level with approximately 10% decrease (Fig. 5i), thereby supporting the observation made using the IAA nanosensor (Fig. 5h). These results corroborate with the understanding that IAA transport occurs from the leaf tip towards the base, followed by transport to the petiole and stem to trigger elongation during SAS14.Auxin Detection in Additional Plant Species Under Shade Stress

[0217] The utility of the disclosed IAA nanosensor in other plant species and stresses was further demonstrated. Similar to the previous experiments, IAA nanosensor were applied to these leaf samples via needleless syringe infiltration followed by nIR imaging. The IAA nanosensor was used to detect shade response in two different species of leafy vegetables - choy sum (Brassica chinensis var. parachinensis) and spinach (Spinacia oleracea) (Fig. 25). In choy sum, a steady increase in the overall IAA level was recorded, which peaked at 6 h shade. On the other hand, spinach leaf demonstrated a more rapid and transient response, as the average IAA level was induced within 1 .5 h shade.Auxin Detection in Nicotiana benthamiana Under Heat Stress

[0218] It was also demonstrated that the present IAA nanosensor in measuring IAA content in N. benthamiana plants under high ambient temperature. Exposure to heat stress resulted in a decreasing normalized signal intensity that indicated increasing IAA levels under high temperature (Fig. 26), which is consistent with the existing literature14.Nanosensor enables visualization of IAA redistribution during root gravitropic response and IAA distribution in cotyledons

[0219] To demonstrate that the IAA nanosensor is able to measure physiological levels of IAA, it was used to detect changes in IAA distribution in root tips undergoing gravitropic response. A suitable method to functionalize plant roots with the IAA Nanosensor was first explored. The present results showed that incubation of plant roots in the solution with IAA nanosensor for 2 d successfully introduced the IAA nanosensor into the root tissue (Fig. 27a), suggesting that the IAA nanosensor undergoes passive uptake into the plant roots. This result was further validated by nIR imaging of Arabidopsis roots incubated with and without the IAA nanosensor (Fig. 27b).

[0220] Arabidopsis roots functionalized with the IAA nanosensor were then tested during gravitropic response. Vertically positioned Arabidopsis seedlings were rotated 90 degrees clockwise to cause a change in the direction of gravity. Constant imaging using the nIR stand-off camera revealed a gradual and asymmetrical change in nIR intensity of the root tip, as the lower side of the root showed signal quenching while the upper side retained similar signal intensity (Fig. 6a). Likewise, tomato seedlings undergoing gravitropic response displayed nIR quenching in the lower side but turn-on response on the upper side of the root tip (Fig. 6b). The larger nanosensor gradient in the tomato root tip could be attributed to stronger root gravitropic response in tomato seedlings than Arabidopsis seedlings. While Arabidopsis displays 30-40° root bending at 6 h of gravitropic stimulus63, tomatoseedlings approximately 50° root bending at a similar time point64. These suggests that the IAA nanosensor reported the redistribution of IAA in the root tip during gravitropic response.

[0221] To obtain a higher magnification and resolution of the IAA nanosensor signal, nIR confocal microscopy was utilized to measure the Arabidopsis root tip during gravitropic response. Importantly, the nIR signal was found to overlap with cellular features in the root tip, supporting the notion that the IAA nanosensors localized into the root cells (Fig. 6c). nIR fluorescence before gravitropic response was symmetrically distributed in both upper and lower halves of the root tip in control seedlings (Fig. 6c). However, upon inducing gravitropic response, nIR fluorescence quenched in lower half of the root tip, while the upper half displayed a turn-on response (Fig. 6c). These results indicated that there is an accumulation of IAA in the lower side of the root during gravitropic response, which is consistent with existing literature and the established auxin biosensor Dll-VENUS (Fig. 28)21,65.

[0222] The IAA nanosensor was further demonstrated by visualizing auxin distribution in cotyledons of light-grown Arabidopsis seedlings. Cotyledons functionalized with IAA nanosensor showed strong quenching of the nIR signal at the cotyledon apex (red arrowhead, Fig. 6d) and cotyledon edge (blue arrowheads, Fig. 6d), which indicated higher IAA content in these parts of the cotyledon. To verify the results, the distribution pattern was compared to auxin-responsive DR5-GFP. Strong GFP signal was also found in the cotyledon apex and cotyledon edge, which indicates higher auxin content in these tissues and corroborates with the IAA nanosensor results (Fig. 6d). Taken together, it was shown that the IAA nanosensor signal can be measured at the cellular level and under natural physiological conditions.

[0223] Example 2 - Discussion

[0224] Auxin IAA is a vital hormone that contributes to plant development and its response to environmental stresses. As changes to IAA levels and distribution are short-lived, accurate and realtime quantification and visualization of IAA levels in planta are critical for early diagnosis of plant stress, thereby optimizing agricultural yield and quality14. Direct quantification of in vivo IAA concentration using LC-MS requires sample homogenization, resulting in delayed measurements that lack spatial resolution66’67. In contrast, indirect measurements using genetically-encoded fluorescent reporter systems require genetic engineering of plants and are primarily used for visualizing auxin in roots rather than green tissues like leaves2021. While IAA is biosynthesized in the leaves and regulates leaf growth, development, and response to environmental stimuli68, chlorophyll autofluorescence in leaves strongly interfere with the signals from conventional fluorescent auxin reporters51’52’69. To enable easy monitoring of IAA content in the leaves, the emerging field of plant nanobionics was leveraged on, which intersects nanotechnology and plant biology. By using nanomaterials with nIR fluorescence, sensors can bedesigned and customized to detect a wide range of analytes with great sensitivity and selectivity7071. For instance, the inventors have previously developed a library of biocompatible nanosensors that can differentiate endogenous H2O2 signals under plant stresses5, detect trace exogenous synthetic auxin in planta7, and monitor arsenic uptake in the root system8.

[0225] In this study, it was present a CoPhMoFte-based IAA nanosensor that allows for continuous, real-time measurements of IAA in living plants, by quantifying changes in the nIR fluorescence signal of the sensor. By using a biomimetic design to resemble the natural binding site between IAA and TIR1 , it was shown that the IAA nanosensor can confer selectivity and sensitivity to IAA in vitro and in vivo. The disclosed sensor displayed direct and reversible binding of IAA, which allowed for the detection of transient changes. The sensor also displayed highly stable fluorescence signal, which allowed for long-term monitoring of IAA content and visualization of IAA distribution and movement in live leaf tissue. Lastly, the IAA nanosensor can be easily applied across various plant species without genetic engineering.

[0226] The IAA nanosensor has been validated both in vitro and in vivo. Under in vitro conditions, it was found that the sensor showed fluorescence quenching in response to IAA regardless of the tested buffer conditions. The sensor was also screened against other lAA-related analytes and acceptable selectivity and sensitivity for IAA was found. Crucially, the sensor was shown to have reversible response to IAA, which enabled it to be useful in detecting transient changes to IAA content in a spatiotemporal manner. For in vivo validation of the IAA nanosensor, several approaches to demonstrate its functionality were utilized. Firstly, XVE::iaaM Arabidopsis plants were utilized, which has controllable endogenous IAA levels that depend on the application of an external inducer. The present results showed that the nanosensor exhibited a dose-dependent response to inducer treatment and the corresponding IAA levels. Then the IAA Nanosensor was applied to XVE::iaaM plants for tracking real-time spatiotemporal changes in IAA content, which can be used to visualize IAA diffusion and transport in the leaf.

[0227] The IAA nanosensor was further demonstrated to detect changes in IAA levels in response to shade, as auxin plays a critical role in shade response and the development of SAS phenotypes. Using N. benthamiana plants, the sensor detected an increase in IAA levels near the leaf tip area within the first 3 h of shade treatment. Thereafter, the IAA nanosensor visualized IAA transport from the leaf tip to base. These findings agree with previous observations of auxin activity in SAS, where auxin was transported down towards the leaf base, then moved to the petiole and stem to promote elongation and hyponasty14. The disclosed IAA sensor revealed a transient increase in IAA level that peaked at approximately 3 h, before returning to baseline afterwards. This result reflects theupregulation of IAA biosynthesis at the early stage of SAS, followed by its transport to the leaf base, which was independently verified via LC-MS. Conversely, under normal growth conditions, the IAA nanosensor gave an invariant response, indicating that the IAA nanosensor specifically detects the induction of IAA levels during SAS.

[0228] The IAA Nanosensor was also shown to function other types of plant stress response such as heat stress14. Under heat stress, the IAA nanosensor reported a distinct increase in overall IAA levels. This early detection of elevated IAA further supports the versatility and usefulness of the IAA nanosensor in monitoring plant health under challenging environmental conditions72. Moreover, the IAA nanosensor was demonstrated in multiple plant species from a diverse range of families, including A. thaliana and Choy Sum from the Brassicaceae family, N. benthamiana and Tomato from the Solanaceae family, and Spinach from the Amaranthaceae family. Amongst these plant species, Arabidopsis and N. benthamiana were also selected to represent model plants commonly used in research, while Spinach, Choy Sum, and tomatoes were selected as agriculturally important vegetables. It can potentially serve as an invaluable tool for farmers to promptly identify and mitigate plant stresses, thereby ensuring optimal crop growth and quality in the face of climate change. Furthermore, it was demonstrated that the IAA nanosensor exhibits the versatility of functioning in various tissue types (leaf, root, and cotyledon), as well as the sensitivity to measure IAA concentration and distribution at physiological levels such as in root gravitropic response.

[0229] However, the current iteration of the IAA nanosensor can be further modified to improve its performance. One possible aspect is to incorporate an internal reference signal that can be used for normalization of the IAA nanosensor response, as opposed to the current experimental design of a separate reference sensor. This can be achieved by using single chirality SWNTs for selective fluorescence with specific excitation wavelength46or by combining the spectrofluorometer with Raman spectroscopy to use the characteristic G-band as an internal reference73. These methods can provide accurate scaling of the nIR fluorescence intensity of the IAA nanosensor without the need for an external reference sensor. Another aspect for improvement could be increasing the magnification and resolution of the captured nIR images. While the current stand-off detection system allows macroscopic measurements of the whole leaf, it cannot visualize IAA content at the cellular level. Development of a high magnification nIR system will allow for the IAA nanosensor to be applied at the microscopic level. This means that the sensor can be potentially used to study IAA and its impact on early plant development68. Furthermore, while this study focused on testing the IAA nanosensor in leaf tissue as a proof-of-concept, it has the potential to be used in other plant tissues with appropriate delivery techniques such as microneedles-assisted target delivery74, pressurized chamber75or vacuum infiltration4. Lastly, as detection and application of the IAA nanosensor is similar to other nIRnanosensors that was previously developed48, these nanosensors could be multiplexed for concurrent measurement of various analytes or phytohormones.

[0230] Example 3 - Conclusion

[0231] In conclusion, a CoPhMoRe-based IAA nanosensor has been developed, that enables direct visualization of IAA in living plants. Using this sensor, IAA concentrations were accurately measured and its distribution was visualized in live plant tissue. Importantly, the sensor was shown to detect plant response to abiotic stresses such as shade and heat stress. This suggests that the IAA nanosensor can be utilized as a diagnostic tool for early detection of plant stress in agriculture. The present work also highlights the potential of plant nanobionics in measuring and visualizing auxin in planta. Looking ahead, it is envisioned that the disclosed sensor technology could be further explored for the detection of other plant analytes, presenting a powerful tool for plant biology and agriculture research.

[0232] Example 4 - MethodsGeneral procedure for synthesis of polyamic sodium salts

[0233] All reagents were purchased from Sigma Aldrich and Tokyo Chemical Industry (TCI). A typical procedure for the synthesis of polyamic sodium salt is as follow. In a round bottom flask under argon atmosphere was added one molar equivalence of dianhydride and one molar equivalence of diamine, followed by addition of anhydrous N-methylpyrrolidone (NMP) (10 wt%). After stirring at room temperature for 24 h, excess volume of NaOH 0.1 N was added dropwise to the reaction mixture to completely neutralize the carboxylic acid groups. Precipitation was initially observed which gradually dissolved to give a clear solution with pH ~13 - 14. The resulting solution was dialyzed against deionized (DI) water using regenerated cellulose membrane (12-14 kDa molecular weight cut-off) for 48 h where the water reservoir was refreshed every 12 h. After dialysis, the aqueous solution was frozen, followed by freeze-drying to obtain the polymer as a dry powder. The polymers were stored at -20 °C for later experiments.General procedure for preparation of polymer-SWNT complexes (1)-(20)

[0234] A suspension of 5 mg purified high-pressure carbon monoxide SWNTs (Nanolntegris, lot # HP32-018) in corresponding aqueous polymer solution (25 mg, 5 mL DI water) was tip-sonicated at 22% amplitude (Qsonica, pulse mode: 5s ON, 2s OFF) for 1 h in an ice-bath. The resulting suspension was then ultra-centrifuged (35,500 rpm) for 4 h. Approximately 80% of the upper supernatant wascarefully collected. SWNT concentration was estimated by UV-Vis spectrophotometry (Agilent Cary 5000) using SWNT absorbance at 632 nm with an extinction coefficient of 0.036 (mg L'1)-1cm'1.In vitro screening of plant hormone analytes

[0235] For plant hormone screening, 1 mL of stock solutions containing 100 mM of each analyte dissolved in dimethyl sulfoxide (DMSO) for indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), gibberellic acid (GA3), salicylic acid (SA), and methyl jasmonate (MeJA), or in NaOH 100 mM for IAA were prepared. Stock solutions of SWNT suspension with a concentration of 2 mg L'1in 2-(M-morpholino)ethanesulfonic acid (MES) buffer (10 mM, pH 5.5) were also prepared. SWNT fluorescence was measured in a quartz cuvette (1 pL of analyte solution was added to 999 pL of SWNT solution in a quartz cuvette) using home-built stand-off nIR camera set up with excitation wavelength of 785 nm and laser power of 30 mW. Fluorescent intensity was measured before and after the addition of analytes.Confocal Raman spectroscopy of leaf tissue and isolated protoplasts

[0236] To isolate protoplasts, leaves were cut into strips of 1 mm width, which were then submerged in the digestion buffer [1% (w / v) Cellulase Onozuka R-10 (Yakult Pharmaceutical Industry, Japan), 0.25% (w / v) Macerozyme R-10 (Yakult Pharmaceutical Industry, Japan), 0.4 M mannitol, 20 mM MES (pH 5.7), 20 mM KCI, 10 mM CaCy. The samples were subjected to vacuum infiltration for 10 min and subsequently placed in darkness at room temperature for up to 6 h. Afterwards, the samples were filtered using Miracloth (Calbiochem, USA) to obtain the protoplast suspension. The protoplasts were allowed to sink to the base of the tube before the supernatant was discarded. Subsequently, equal volume of W5 buffer [154 mM NaCI, 125 mM CaCIs, 5 mM KCI, 2 mM MES (pH 5.7)] was added to resuspend the protoplasts. The protoplasts were washed twice more in a similar manner, then resuspended in W5 buffer for confocal Raman spectroscopy.

[0237] Leaf tissue and isolated protoplasts were subjected to confocal Raman spectroscopy. A 40x magnification objective was used. Excitation wavelength of 785 nm was used. A total of 5 spectra was measured per location, with integration time of 2 s per spectra. Processing of Raman spectra were similar as previously described76. Raman shift was calibrated against polystyrene, which has a well- documented Raman spectrum77.Generation of transgenic Arabidopsis plants expressing iaaM

[0238] Pseudomonas iaaM gene (EC 1 .13.12.3) was synthesized and cloned into pUC57 carrier vector (GenScript Biotech). The iaaM gene was then amplified with a Gateway adapter-flanked gene-specific primer pair (Table 2), using pUC57- / aa / W as the template, and cloned into Gateway® donor vector, pDONR221. The iaaM gene was subsequently cloned into pER8-DC51, which contains an estrogen receptor-based transactivator (XVE) system, through Gateway® recombination with pDONR- iaaM for inducible expression. The iaaM gene was also cloned into pBA-DC51harbouring the constitutive promoter of cauliflower mosaic virus 35S (CaMV 35S) for transient expression in N. benthamiana. pER8- iaaM and pBA- / aa / W plasmids were transformed into the A. tumefaciens strain, GV3101. Wild-type Arabidopsis (Col-0) was transformed with pER8- / aa / Wusing the floral dipping method52.

[0239] Table 2. Primers used in the study for iaaM cloning and qRT-PCR

[0240] For the screening of iaaM expression in XVE::iaaM Arabidopsis lines, 10-d-old seedlings were transferred into Vi strength Murashige and Skoog (14 MS) liquid media with addition of 50 pM p- estradiol or DMSO as a mock-treatment control. The seedlings were then incubated overnight (16 h) under continuous white light (WL, Photosynthetic Photon Flux Density, PPFD = 100 pmol cm2s'1) with low agitation at 70 rpm. For concentration-dependent induction experiment, all growth conditions were the kept the same, but induction was carried out for 6 h using different inducer concentrations (0, 1 , 10,25, and 100 pM p-estradiol). For the time-dependent induction experiment, all growth conditions were the kept the same, but induction was carried out using 50 pM p-estradiol at various induction times (0, 1 , 2, 6 and 14 h).In vivo detection of IAA nanosensor using home-build stand-off nIR camera system

[0241] In a typical experimental setup, a dilute aqueous suspension of 10 mg L11AA nanosensor in MES buffer, corresponding to 15 ppm carbon, and aqueous suspension of reference sensor (singlestranded DNA (AT)i5 wrapped CoMoCat (6,5)) were infiltrated onto the abaxial side of Arabidopsis orN. benthamiana leaves by a needleless syringe (Becton Dickinson). The infiltrated or nanosensor- functionalized leaves were allowed to rest for at least 1 h under growing condition before transferring to the home-built stand-off camera setup for nIR imaging. In particular, the nanosensor-infiltrated leaves were mounted and fixed vertically on the platform facing the camera, with a distance of 1 m. Two white LED light sources were also positioned alongside the plant to ensure it is not under any light stress. nIR fluorescence of the infiltrated leaf was imaged using a 785 nm laser with incident power of 20 mW. Each nIR image was captured with using a 2D array InGaAs detector equipped with a 900 nm long-pass filter, with integration time of 30 s and collected by Lightfield® software (Princeton Instruments).

[0242] For IAA detection in XVE::iaaM Arabidopsis plants, 100 pM p-est rad io I supplemented with 0.01 % Silwet L-77 solution was gently applied (on the whole leaf or a designated local spot) on the adaxial surface of 4-w-old Arabidopsis rosette leaf using a paint brush. After 2 h, IAA and reference nanosensor suspensions were infiltrated on abaxial side of the Arabidopsis rosette leaf. The plant was then placed in a growth chamber for another 4 h prior to nIR imaging experiment. To measure IAA reduction upon inhibiting IAA biosynthesis, a similar experiment was carried out using topical application of IAA biosynthesis inhibitor solution (50 pM Yucasin and 10 pM L-Kynurenine) supplemented withO.01% Silwet L-77.

[0243] For shade treatment, 3-w-old N. benthamiana plants were transferred from WL (PPFD = 100 pmol cm2s’1; R:FR = 3.0) to FR-enriched shade condition (PPFD = 20 pmol cm-2s'1; R:FR = 0.2) for up to 8 h. WL was provided by table lamp and FR light was supplemented by ISL-150X150FR (CCS Asia) to achieve the specific R:FR ratio.Image analysis from stand-off camera experiments

[0244] Image analysis from stand-off camera experiment was conducted using FIJI (Fiji Is Just ImageJ) and MATLAB 2021 b. Raw image data (.tiff) from the experiments were deconvoluted using a custom PSF correction function developed in MATLAB to correct photon diffusion and estimate true fluorescence intensity values. The average fluorescence intensity over time was extracted from themanually defined regions of interest (ROIs) drawn consistently across frames for the IAA sensor- functionalized area and reference sensor-functionalized area using either MATLAB or FIJI. Fluorescence intensity at each time point (I) was normalized (l / lo) by dividing it by the average fluorescence intensity of the first five minutes (l0). The average ratiometric intensity was calculated by dividing the average normalized intensity of the IAA nanosensor by that of the reference sensor, compensating for external fluctuations from background noise or laser power variations. The resulting ratiometric data was then used as input for the reversible first-order binding model (see Supporting Information), which correlates fluorescence intensity with IAA concentration by assuming a dynamic equilibrium between bound and unbound IAA molecules, allowing estimation of changes in IAA concentration over time.

[0245] The normalized change in intensity images (l-l0) / l0(e.g., Fig. 3c, 4d, 5b, 5g) were generated by calculating the ratio of pixel intensities at each specific time point to the average pixel intensity from the first five minutes of imaging and subtracting 1 , computed frame by frame.

[0246] The normalized intensity images l / lo (e.g., Fig. 6a-b) were created by dividing the pixel intensity at each specific time point by the average pixel intensity from the first five minutes of imaging, ensuring a consistent baseline for intensity comparison.

[0247] To generate the auxin concentration map (e.g., Fig. 3e, 4e, 5e, and 5f), the normalized intensity of the IAA sensor at each pixel within the IAA sensor-functionalized area was divided by the average normalized intensity of the entire reference sensor-functionalized area over the first five minutes of imaging, producing the ratiometric intensity of the IAA sensor response per pixel. This ratiometric data was then used as input for a custom mathematical model to estimate changes in IAA concentration over time, with the entire process automated using MATLAB.

[0248] Quantification of free IAA

[0249] Samples from Arabidopsis and N. benthamiana were harvested and weighed, before being immediately frozen using liquid nitrogen. IAA phytohormone was then extracted using 80% methanol as described55. Concentration of extracts was normalized to the fresh weight measured after harvest. IAA in the extracts was then quantified by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometer (UPLC-MS / MS) equipped with UltiMate 3000 Rapid Separation LC system (Thermo Fisher Scientific) and the Q Exactive™ Hybrid Quadrupole-Orbitrap™ MS (Thermo Fisher Scientific). Accucore™ RP-MS column (Thermo Fisher Scientific) was used for compound separation. For the detection of IAA precursor ions, parallel reaction monitoring, targeted quantitation, and screening scan mode were conducted. 5 mM acetic acid in 5% (v / v) acetonitrile andin 95% (v / v) acetonitrile were used as mobile phases A and B, respectively. The elution profile was: 0- 3 min, 5% mobile phase B in mobile phase A; 3-6 min, 5-95% mobile phase B in mobile phase A; 6- 10 min 95% mobile phase B in mobile phase A; 10-10.1 min 95-5% mobile phase B in mobile phase A; and 10.1-11 min 5% mobile phase B in mobile phase A. The mobile phase flow rate was 0.3 mL min1. Injection volume was 5 pL. Electrospray ionization was operated in negative ion mode. TraceFinder™ 4.1 (Thermo Fisher Scientific) and Compound Discoverer 3.0 software (Thermo Fisher Scientific) were used to qualify the hormone levels. Hormone measurements were conducted on three biological replicates.

[0250] RNA extraction and quantitative reverse transcription polymerase chain reaction (qRT- PCR)

[0251] Total RNA from plant samples was isolated using the GeneAII Ribospin RNA isolation kit (GeneAII). For cDNA synthesis, 1 pg of total RNA was reverse-transcribed at 42 °C for 90 min and 72 °C for 15 min using the moloney murine leukemia virus (M-MLV) reverse transcriptase (Promega). Each cDNA sample was diluted 8-folds and used for qRT-PCR with the specific primer pairs of each gene listed in Supplementary Table 1 . qRT-PCR was performed using Takara SYBR Premix Ex Taq (Takara Bio) on Biorad CFX connect™ real-time system (Bio-Rad). Each reverse transcript was quantified in triplicate. The thermal cycling program was as follows: pre-denatu ration at 95 °C for 2 min, denaturation at 95 °C for 10 s, followed by annealing and extension at 60 °C for 30 s, with a total of 40 cycles. The comparative threshold (Ct) cycle method (2-AACt) was used for relative quantification and calculations. nIR imaging or microscopy of plant roots

[0252] Seedlings were incubated in1 / 2 MS liquid media with 20 mg L'1IAA sensor and grown under WL and long day condition (16 h light : 8h dark) for 2 d. Subsequently, the seedlings were thoroughly washed thrice with MES buffer pH 5.5, before arranging vertically on1 / s MS agar and acclimatizing in WL for 2 h. nIR imaging was performed using the stand-off nIR camera system, as described. The1 / 2 MS agar containing the vertically arranged seedlings were rotated 90 degrees clockwise, followed by continuous imaging for 1 h. nIR microscopy was performed using a FV3000NIR inverted microscope (Olympus). A 561 nm laser was used for excitation, while a longpass filter and GaAs detector were used to image the nIR emission. Image and data analysis were primarily done using FIJI (Fiji Is Just ImageJ). The despeckle tool was used to reduce noise in the nIR images.Kinetics of fluorescent response to auxin photo-degradation

[0253] To study the kinetics of fluorescent response to auxin photo-degradation, a mathematical model was developed assuming the relationship between the corona phase binding sites and auxin under photodegradation based on the diagram in Figure 13a: hv e - IAA 9 + IAA OxIAA (1)Where the equation rates for concentration occupied binding sites [0 - IAA] and IAA can be written as:dflAA]= ~ka[9][IAA] + kd[9 - IAA] - k0X[IAA] (3)Where fc, and foare the rate constants of association and dissociation respectively of binding process and koxis the degradation rate constant of oxidation of IAA which is an irreversible process. Assuming a pseudo-equilibrium condition for free IAA where the extent of IAA dissociated from corona phase is simultaneously degraded by photo-oxidation such that >1= 0, free IAA concentration can be estimated as: kd[9 — IAA][MX] = ka[6] + kuxBy substituting (4) into (2):Since [0]tot= [0 - IAA] + [0],Assuming that at t = 0, [0 - IAA] = [0 - IAA]O, integrating both sides gives:At early time when t = to, [0 - IAA] - [0 - MA]0« 0At time increases when [0 - IAA] « [0 - IAA]0,we have » [0 - tAA] - [0 - MA]0and( / ca[0]tot + kox) > ka, we can approximate thatTherefore, we can obtain the time-dependence concentration of [0 - 7A4]Where p is proportionality factor. By fitting the model to the time-dependent fluorescent response data, P and apparent constant k' were determined as 0.59 ± 0.1 and 0.043 ± 0.02 (min1) respectively. Theproportionality factor p obtained here is similar to the proportionality factor p obtained from the calibration curve of SWNT (6,5). This is expected because at 600 nm excitation wavelength, fluorescent of (6,5) is the brightest.

[0254] From fc' = kox, it can be implied that the responsiveness of auxin sensor (3)could be improved such that k' « / corwhen the dissociation constant kd« ka[0]tot+ kax. While koxis an intrinsic property of IAA, the dissociation / association constants, k0and ka, can be controlled by using different SWNT chiralities and the concentration of total binding sites [0]£o(is a variable that highly dependent on the surface coverage of adsorbed polymer on nanoparticle surface. Therefore, this kinetic model proposes an opportunity for improvement of sensor sensitivity and responsiveness by tuning the concentration of binding sites as well as appropriate choice of SWNT chirality.

[0255] Likewise, the kinetic of photodegradation of IAA can be simplified by the following hv irreversible reaction: IAA -> oxIAA', assuming that this is a first order kinetic process, the time dependence concentration of IAA can be written as:Where koxis degradation rate constant. Because the nIR fluorescent intensity almost returned to its initial intensity after one hour, it may be assumed that IAA is almost completely degraded ([ZA4]t=60= 0) at t = 60 min. Assuming that the IAA concentration is proportional to its absorbance value Abstat 280 nm, it is possible to derive that:Where Abst=60accounts for absorbance value background when [IAA] = 0. Value of koxwas obtained as 0.071 min1by fitting to time-dependence absorbance value at 280 nm, where orange line is the fitting curve to blue data points (calculated from absorbance values as shown in equation (2).Reversible first-order binding model for IAA nanosensorThe binding event between IAA nanosensor (S) and IAA may be assumed as a first-order reversible reaction: kfIAA + S - S - IAA kb

[0256] kfand kbare forward and backward rate constants.The rate of reaction can be described by the following equation:At the initial stage of binding events, the sensor and the analyte are close to their original concentrations, |5| ~ [S]o,[MA] ® [M / l]0and |S - IAA] ~ 0, therefore:Assuming that therefore:Therefore, the forward reaction rate isAt equilibrium, we have d[S]= - fcr[S] [M / 1] + kb[S - IAA] = 0 dtTherefore,From mass balance equation:Therefore,Therefore,The concentration [IAA] can then be approximated d[S]-fcz[S][MX] + kb[S - MX] dt d[S] dt - kb[S - MX][MX] =-M5]From equation (1 ) and (2), the kband kfparameter for IAA nanosensor were estimated using in vitro kinetic data: k f « 6.4 x 10 uM s k « 2.1 x io'4s'1One-dimensional steady-state reaction-diffusion modelFor the data in Figure 4c, we develop a model for the spatial IAA distribution from the midrib (z = 0) to the margin of the leaf (z = L) in the treated side of the leaf. IAA (C) is produced with rate y across the induced site with a distribution modeled by a Gaussian function centered about a with standard deviation <j. IAA is inactivated and reacted away with rate ksinkthroughout the leaf and is free to diffuse within the leaf with diffusivity Df. The mass balance is as follows:with boundary conditionsDfC(0) = 0, (S2)DfC(E) = —kc(C(L) - Cro) = —kcC(E). (S3)Here, kcis a mass transfer rate between the blade of the leaf and the margin of the leaf, and a convective boundary condition is used to model the margin (Equation S3). We assume that IAA concentration is negligible in the margins C„, = 0. Equation S2 represents the midrib of the leaf as an impermeable boundary.To facilitate analysis, we introduce the following non-dimensional variables:which yields dimensionless groupsHere, Cois the initial auxin concentration before induction. Rewriting the dimensionless mass balance yieldswith boundary conditionsC'(0) = 0, (S7)C'(l) = -kmarginC(l). (S8)For data analysis, a representative strip of data approximately centered about the induced spot was averaged into one dimension. A Gaussian-weighted moving average filter with a window of 30 was applied to the data.

[0257] The Damkohler number can be rewritten as represents thelength of the reaction zone for IAA. Taking the analyzed region to have L = 0.48 cm, and averaging the fitted Damkohler numbers to get 0 = 3.4, we calculate A = 0.14 cm.

[0258] In the present disclosure, all terms referred to in singular form are meant to encompass plural forms of the same. Likewise, all terms referred to in plural form are meant to encompass singular forms of the same. In addition, the use of “or” means “and / or” unless otherwise stated. The term “plurality” as used herein means more than one, for example, two or more, three or more, four or more, and the like. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0259] It should be understood that the compositions, uses, methods, kit and polymers are described in terms of "comprising," "containing," or "including" various components or steps, the methods can also "consist essentially of’ or "consist of’ the various components and steps. Moreover, the indefinite articles "a" or "an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0260] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, "from about a to about b," or,equivalently, "from approximately a to b," or, equivalently, "from approximately a-b", or equivalent, “from a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0261] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual embodiments are discussed, the disclosure covers all combinations of all those embodiments. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.

[0262] All references cited herein are herein incorporated by reference in their entirety.

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Claims

CLAIMSWHAT IS CLAIMED IS:1 . A composition comprising: a polymer of a polyamic sodium salt adsorbed on a single-walled carbon nanotube (SWNT), wherein the polymer of the polyamic sodium salt adsorbed on the SWNT forms a combination of corona phases comprising a selective binding site for an auxin.

2. The composition of claim 1 , wherein the polymer of the polyamic sodium salt comprises one or more of each of an aromatic dianhydride monomer and an aromatic diamine monomer.

3. The composition of claim 1 or 2, wherein the polymer of the polyamic sodium salt comprises one or more monomers of each of 4,4'-oxydiphthalic anhydride (OPDA) and 6,6'-diamino-2,2'-bipyridyl (26DAPB).

4. The composition of any one of claims 1 -3, wherein the polymer of the polyamic sodium salt is:, wherein n=15-30.

5. The composition of any one of claims 1 -4, wherein the SWNT is photoluminescent.

6. The composition of any one of claims 1 -5, wherein the SWNT is near-infrared photoluminescent.

7. The composition of any one of claims 1 -6, wherein a wavelength and / or an intensity of fluorescence of the SWNT in the absence of the adsorbed polymer of the polyamic sodium salt is different from a wavelength and / or an intensity of fluorescence of the SWNT adsorbed with the polymer of the polyamic sodium salt.

8. The composition of any one of claims 1 -7, wherein the polymer of the polyamic sodium salt comprises a wrapping polymer, the wrapping polymer comprising the polymer of the polyamic sodium salt adsorbed to the SWNT in a single-handed helix conformation.

9. The composition of any one of claims 1 -8, wherein the polymer of the polyamic sodium salt is adsorbed to the SWNT at about 50 mg / L to about 200 mg / L.

10. The composition of any one of claims 1 -9, wherein the selective binding site for the auxin comprises a synthetic indole-3-acetic acid (IAA) binding pocket.1 1 . The composition of any one of claims 1 -10, wherein the selective binding site for the auxin comprises hydrogen bonding and hydrophobic interactions between the auxin and transport inhibitor response 1 (TIR1).

12. The composition of any one of claims 1 -1 1 , wherein the selective binding site for the auxin comprises at least one of:(i) a salt-bridge interaction between an indole-3-acetic acid (I AA) carboxyl group and a guanidium residue of arginine 403 of transport inhibitor response 1 (TIR1 ) together with hydrogen bonding of the IAA carboxyl group to another hydroxyl residue of TIR1 serine residue 438;(ii) hydrophobic and van der Waals interaction between an indolic group of the IAA and phenyl residues 79 and 82 of the TIR1 ; and(iii) hydrogen bonding between an indolic nitrogen of the IAA and a carbonyl on the side of a TIR1 binding pocket.

13. The composition of any one of claims 1 -12, wherein the selective binding site does not substantially bind to one or more of: gibberellic acid, abscisic acid, jasmonic acid, salicylic acid, indole-3-propionic acid, indolebutyric acid, L-tryptophan, phenylacetic acid, 2-oxindole-3-acetic acid, indole-3-acetyl- aspartate and 1 -naphthaleneacetic acid.

14. The composition of any one of claims 1 -13, wherein the auxin selectively binds the polymer of the polyamic sodium salt adsorbed on the SWNT at a concentration of about 0.1 pM or greater.

15. The composition of any one of claims 1 -14, wherein the estimated dissociation constant coefficient (Kd) of the composition to the auxin calculated using:I - Ip \e - IAA\ ip [0]totis between about 1.2 pM and about 5.0 pM, wherein £ is proportional factor showing the maximum optical modulation, I is an auxin fluorescence, l0is a normalized fluorescent intensity change before and after addition of I, [0 - IAA] is a total number of binding sites, and [0£ otai] is a number of occupied binding sites.

16. The composition of any one of claims 1 -15, wherein the auxin comprises indole-3-acetic acid (IAA) and / or indole-3-pyruvate (IPA).

17. The composition of any one of claims 1 -15, wherein the auxin comprises indole-3-acetic acid (IAA).

18. The composition of claim 16 or 17, wherein the IAA and the IPA have different binding parameters to the selective binding site.

19. The composition of any one of claims 1 -18, wherein the polymer of the polyamic sodium salt is free from selective binding to the auxin in the absence of being adsorbed on the SWNT.

20. A method of adsorbing the polymer of the polyamic sodium salt as defined in any one of claims 1 - 19 to a single-walled carbon nanotube (SWNT), the method comprising conjugating the polymer of the polyamic sodium salt with the SWNT.21 . The method of claim 20, wherein the polymer of the polyamic sodium and the SWNT are non- covalently conjugated.

22. The method of claim 20 or 21 , wherein the conjugating comprises sonication.

23. The method of any one of claims 20-22, further comprising a step of forming the SWNT with high- pressure carbon monoxide.

24. The method of any one of claims 20-23, wherein the adsorption of the polymer of the polyamic sodium salt to the SWNT changes a wavelength and / or an intensity of fluorescence of the SWNT.

25. A method of detecting an auxin, the method comprising: applying the composition of any one of claims 1 -19 to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

26. A method of detecting an auxin in vivo, the method comprising: applying the composition of any one of claims 1 -19 to one or more cells of an organism;measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

27. The method of claim 26, wherein the organism is a plant or a plant seed.

28. The method of claim 26 or 27, wherein the organism is selected from the group consisting of Nicotiana benthamiana, an Arabidopsis, choy sum (Brassica chinensis var. parachinensis), kai Ian, and spinach (Spinacia oleracea).

29. The method of any one of claims 25-28, further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of claims 1 -19; and determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

30. The method of claim 29, wherein the measured reference wavelength is subtracted from the measured wavelength and / or the measured reference intensity of fluorescence is subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.31 . A method of detecting a change in an auxin level and / or a change in an auxin distribution, the method comprising: applying the composition of any one of claims 1 -19 to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; anddetermining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

32. The method of claim 31 , wherein the measured first wavelength is subtracted from the measured second wavelength and / or the measured first intensity of fluorescence is subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

33. The method of claim 31 or 32, wherein the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells comprises a measurement after a duration of time and / or a stimulus.

34. The method of claim 33, wherein the stimulus comprising one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

35. The method of any one of claims 31 -34, further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of claims 1 -19; and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

36. The method of claim 35, wherein the measured reference wavelength is subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence is subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

37. A kit for detecting an auxin in vivo comprising the composition of any one of claims 1 -19 and at least one of: instructions for performing the method of any one of claims 25-36;one or more reagent for performing the method of any one of claims 25-36; and one or more buffers.

38. The composition of any one of claims 1 -19 for use in detecting an auxin, wherein the detecting comprises: applying the composition to one or more cells; measuring a wavelength and / or an intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

39. The composition of any one of claims 1 -19 for use in detecting an auxin in vivo, wherein the detecting comprises: applying the composition to one or more cells of an organism; measuring a wavelength and / or an intensity of fluorescence of the one or more cells of the organism applied with the composition; and determining, based on the measured wavelength and / or the measured intensity of fluorescence, the presence or absence of the auxin in the one or more cells of the organism applied with the composition.

40. The composition for use of claim 39, wherein the organism is a plant or a plant seed.41 . The composition for use of claim 39 or 40, wherein the organism is selected from the group consisting of Nicotiana benthamiana or an Arabidopsis, choy sum {Brassica chinensis var. parachinensis), kai Ian, and spinach (Spinacia oleracea).

42. The composition for use of any one of claims 38-41 , further comprising: measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of claims 1 -19; and determining, based on the measured wavelength and / or the measured intensity of fluorescence and the measured reference wavelength and / or the measured reference intensity offluorescence, the presence or absence of the auxin in the one or more cells applied with the composition.

43. The composition for use of claim 42, wherein the measured reference wavelength is subtracted from the measured wavelength and / or the measured reference intensity of fluorescence is subtracted from the measured intensity of fluorescence to determine the presence or absence of the auxin in the one or more cells applied with the composition.

44. The composition of any one of claims 1 -19 for use in detecting a change in an auxin level and / or a change in an auxin distribution, wherein the detecting comprises: applying the composition to one or more cells; measuring a first wavelength and / or a first intensity of fluorescence of the one or more cells applied with the composition; measuring a second wavelength and / or a second intensity of fluorescence of the one or more cells applied with the composition; and determining, based on the measured first wavelength and the measured second wavelength and / or the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

45. The composition for use of claim 44, wherein the measured first wavelength is subtracted from the measured second wavelength and / or the measured first intensity of fluorescence is subtracted from the measured second wavelength to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

46. The composition for use of claim 44 or 45, wherein the measuring the second wavelength and / or the second intensity of fluorescence of the one or more cells comprises a measurement after a duration of time and / or a stimulus.

47. The composition for use of claim 46, wherein the stimulus comprising one or more of: treatment with one or more compounds, a stress, normal growth conditions, a genetic modification, an increase or a decrease in expression of a gene, adverse growth conditions or any combination thereof.

48. The composition for use of any one of claims 44-47, further comprising:measuring a reference wavelength and / or a reference intensity of fluorescence of one or more reference cells not applied with the composition of any one of claims 1 -19; and determining, based on the measured reference wavelength, the measured first wavelength and the measured second wavelength and / or the measured reference intensity, the measured first intensity and the measured second intensity of fluorescence, the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

49. The composition for use of claim 48, wherein the measured reference wavelength is subtracted from the measured first wavelength and the measured second wavelength and / or the measured reference intensity of fluorescence is subtracted from the first measured intensity of fluorescence and the second measured intensity of fluorescence to determine the change in the auxin level and / or the change in the auxin distribution in the one or more cells applied with the composition.

50. A polymer of a polyamic sodium salt, wherein the polymer is:, wherein n=15-30.51 . A method, process, composition, use, kit, pharmaceutical composition, or compound as substantially described herein.

52. The invention as substantially described herein.

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