Near-infrared fluorescent nano-probe for detecting carbon monoxide as well as preparation method and application of near-infrared fluorescent nano-probe

Abstract

The invention discloses a near-infrared fluorescent nanoprobe for detecting carbon monoxide and a preparation method and application thereof, the probe is an FRET type probe, the structure of the probe is a core-shell structure, and lanthanide doped up-conversion nanoparticles (UCNPs) are used as a core and an energy donor; a metal organic framework (MOF) is used as a shell, a shell layer entraps Rhp to serve as an energy receptor, and the outer surface of the shell layer is modified by PEG (Polyethylene Glycol). The excitation wavelength of the probe is 980 nm, the emission wavelength is 540 nm, the detection limit is 7.7 * 10 <-8 > M, and the probe has the advantages of high tissue penetrability, low autofluorescence interference and deep tissue penetrating power; after the surface is subjected to PEGylation modification, the water solubility and stability of the material can be effectively improved, the distribution of the material in vivo is improved, and the material is particularly suitable for detecting endogenous CO in deep tissues of a living body.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent probes, and in particular to a near-infrared fluorescent nanoprobe for detecting carbon monoxide, and a preparation method and application thereof. Background Art

[0002] Carbon monoxide (CO) is an indispensable key signaling molecule in organisms. Abnormal endogenous CO concentration is often closely related to the occurrence and development of various diseases. Therefore, the development of convenient visual detection probes is an urgent problem to be solved in the study of endogenous CO. Visual detection probes can be used not only for the study of the biological functions of endogenous CO, but also for the diagnosis and auxiliary treatment of related diseases.

[0003] At present, most fluorescent probes used for CO detection in vivo contain palladium, and their detection mechanism is either based on the hydrolysis of palladium or the palladium-mediated Tsuji-Trost reaction. Common problems of these probes are: complex synthesis process, photobleaching, high background fluorescence, poor tissue targeting, low sensitivity, poor membrane penetration, and inconvenience in use. Therefore, it is particularly important to design new CO fluorescence detection probes based on new reaction mechanisms.

[0004] Fluorescence resonance energy transfer (FRET) probes have two fluorescent groups, one of which acts as an energy donor and the other as an energy acceptor. When excited by light of a certain wavelength, the fluorescent group that acts as an energy donor emits fluorescence and transfers energy to the energy acceptor in a radiation-free manner through the dipole-dipole interaction, thereby causing fluorescence resonance energy transfer. The conditions for effective energy transfer between the energy donor and the energy acceptor as fluorescent groups are very harsh: (1) the emission spectrum of the energy donor and the absorption spectrum of the energy acceptor must overlap or be very close; (2) the energy donor and the energy acceptor must be close enough. In addition, due to factors such as quantum yield, extinction coefficient, water solubility, and anti-interference ability, it is very difficult to find a suitable energy donor-energy acceptor pair.

[0005] Therefore, it is necessary to develop a near-infrared fluorescent nanoprobe for detecting carbon monoxide. Summary of the invention

[0006] The purpose of the present invention is to provide a near-infrared fluorescent nanoprobe for detecting carbon monoxide and a preparation method and application thereof. The near-infrared fluorescent nanoprobe is a FRET-type probe with a larger Stokes shift and high sensitivity. The probe can be used for the detection of endogenous CO.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In the first aspect of the present invention, a near-infrared fluorescent nanoprobe for detecting carbon monoxide is provided. The near-infrared fluorescent nanoprobe for detecting carbon monoxide is a core-shell nanocomposite material composed of lanthanide-doped upconversion nanoparticles as a core layer and an acid-resistant metal organic framework as a shell layer, wherein the shell layer is loaded with Rhp and the outer surface of the shell layer is modified with PEG.

[0009] Furthermore, the average hydrodynamic diameter of the near-infrared fluorescent nanoprobe is 100-200 nm.

[0010] Furthermore, the acid-resistant metal organic framework includes UiO-68-NH 2 , PCN-222, PCN-224.

[0011] Furthermore, the lanthanide-doped upconversion nanoparticles are NaYF 4 :Yb,Er@NaYF 4 .

[0012] A second aspect of the present invention provides a method for preparing a near-infrared fluorescent nanoprobe for detecting carbon monoxide, the method comprising:

[0013] S1, dissolving the raw material of the acid-resistant metal organic framework in an organic solvent and stirring to obtain a mixed solution; dissolving the lanthanide-doped upconversion nanoparticles in an organic solvent and adding them to the mixed solution for ultrasonic and post-heating reaction, and then centrifuging to collect the precipitate to obtain core-shell nanoparticles composed of the upconversion nanoparticles and the metal organic framework;

[0014] S2, dissolving the core-shell nanoparticles composed of the upconversion nanoparticles and the acid-resistant metal organic framework in an organic solvent, adding Rhp, continuously stirring the reaction to load the acid-resistant metal organic framework with the Rhp, then washing with water, collecting the supernatant by centrifugation, and freeze-drying to obtain core-shell Rhp-loaded nanoparticles;

[0015] S3, dissolving the core-shell loaded Rhp nanoparticles in water, adding the homobifunctional PEG, continuously stirring the reaction, centrifuging, collecting the precipitate, and obtaining the near-infrared fluorescent nanoprobe for detecting carbon monoxide.

[0016] Furthermore, in S1, the ultrasonic time is 1-30 min, and the heating temperature is 50-150°C.

[0017] Furthermore, in S1, the mass ratio of the acid-resistant metal organic framework to the lanthanide-doped upconversion nanoparticles is 1:(4-6).

[0018] Furthermore, in S2, the mass ratio of the acid-resistant metal organic framework to the Rhp is 1:(1.2-2), preferably 1:1.7.

[0019] Furthermore, in S3, the bifunctional PEG includes at least one of SCM-PEG-SCM, SS-PEG-SS, and GAS-PEG-GAS.

[0020] Furthermore, the mass ratio of the acid-resistant metal organic framework to the SCM-PEG-SCM is 1:(7-8), preferably 1:7.5.

[0021] As a specific embodiment, the acid-resistant metal organic framework is UiO-68-NH 2 When the raw material used for PEG modification of the outer surface of the shell is SCM-PEG-SCM, the preparation method comprises the following steps:

[0022] S1. Dissolve amino-TPDC and zirconium (IV) chloride in DMF and stir to mix them evenly. After CA-UCNP is dissolved in DMF, add it to the above mixture, sonicate for 5 minutes and then heat at 90°C for 5-10 hours to form a metal organic framework on the surface of CA-UCNP with CA-UCNP as the core as the shell, centrifuge and collect the precipitate to obtain UCNP@UiO-68-NH 2 ;

[0023] S2, UCNP@UiO-68-NH 2 The nanoparticles were dissolved in DMF, Rhp was added, and stirred at room temperature for 5 to 24 hours to make the acid-resistant metal organic framework UiO-68-NH 2 Load Rhp, wash with water, remove unloaded Rhp, centrifuge, collect the supernatant, and freeze-dry to obtain MOF@UCNP@Rhp;

[0024] S3, MOF@UCNP@Rhp was dissolved in water, and the homobifunctional PEG was added, stirred at room temperature for 5-24 hours, centrifuged, and the precipitate was collected to obtain a near-infrared fluorescent nanoprobe for detecting carbon monoxide.

[0025] The third aspect of the present invention provides the use of the near-infrared fluorescent nanoprobe for detecting carbon monoxide in the preparation of a carbon monoxide detection product.

[0026] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0027] 1. In order to ensure that the distance between the energy donor and the energy acceptor is close enough to cause FRET in the prior art, the traditional FRET probe usually has the energy donor and the energy acceptor in the same molecule, and the two are connected by a suitable connecting arm, and the preparation process is complicated. The near-infrared fluorescent nanoprobe provided by the present invention is a FRET probe, which has a core-shell structure, with lanthanide-doped upconversion nanoparticles (UCNPs) as the core as the energy donor; with a metal-organic framework (MOF) as the shell, and the shell loads Rhp as the energy acceptor. The preparation process of the probe is simple, and it has been experimentally confirmed that it has good biocompatibility, can be used for the detection of endogenous CO in organisms, and has good application prospects.

[0028] 2. The near-infrared fluorescent nanoprobe provided by the present invention has an excitation wavelength of 980nm, which belongs to the near-infrared region. It has the advantages of high tissue penetration, low autofluorescence interference, and deep tissue penetration, and is particularly suitable for the detection of endogenous CO in deep tissues of living bodies. The near-infrared fluorescent nanoprobe provided by the present invention has an emission wavelength of 540nm and a detection limit of 7.7×10 - 8 M,

[0029] 3. After the surface of the near-infrared fluorescent nanoprobe provided by the present invention is modified by PEG, its water solubility and stability can be effectively increased, and its distribution in the body can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 FT-IR images of OA-UCNP, ligand-free UCNP, and CA-UCNP.

[0032] Figure 2 Scanning electron microscopy images of OA-UCNP (Figure A) and MOF@UCNP (Figure B).

[0033] Figure 3 This is the energy spectrum of MOF@UCNP.

[0034] Figure 4 Dynamic light scattering diagrams of UCNP, MOF@UCNP, and R@MUP.

[0035] Figure 5 FT-IR images of R@MU and R@MUP.

[0036] Figure 6 Comparison of spectra of MOF@UCNP (Figure A) and R@MUP (Figure B).

[0037] Figure 7 Figure 1 is the effect of relevant active substances and pH on the selectivity of R@MUP for CO. Figure A is the effect of relevant active substances on the selectivity of R@MUP for CO, and Figure B is the effect of pH on the selectivity of R@MUP for CO.

[0038] Figure 8 Cell viability graph of L02 cells and CT26 cells after treatment with different concentrations of R@MUP.

[0039] Fig. 9 Confocal microscopy upconversion luminescence images after CT26 cells were incubated with different nanoparticles and different concentrations of CO (via CORM-2) or APAP (scale bar: 20 μm. Excitation: 980 nm).

[0040] Fig.10 This is a confocal microscopy upconversion luminescence image of mouse liver tissue sections (scale bar: 50μm. Excitation: 980nm).

[0041] Fig.11 The present invention provides a flow chart of a method for preparing a near-infrared fluorescent nanoprobe for detecting carbon monoxide. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0043] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained by existing methods.

[0045] The relevant terms of the present invention are explained as follows:

[0046] Rhp: [Rh 2 (C 6 H4 PPh 2 ) 2 (O 2 CCH 3 ) 2 ](CH 3 COOH) 2 .

[0047] UCNP: upconversion nanoparticles.

[0048] OA-UCNP: oleic acid OA conjugated upconversion nanoparticles.

[0049] CA-UCNP: caffeic acid CA conjugated upconversion nanoparticles.

[0050] UCNP@UiO-68-NH 2 (also known as MOF@UCNP): core-shell nanoparticles formed by upconversion nanoparticles and metal-organic frameworks.

[0051] MOF@UCNP@Rhp (also known as R@MU): Nanoparticles formed by MOF@UCNP encapsulating Rhp.

[0052] MOF@UCNP@Rhp-PEG (also known as R@MUP): Nanoparticles formed after the surface of MOF@UCNP@Rhp is modified by PEG.

[0053] CORM-2: Carbon monoxide releasing molecules-2. Carbon monoxide releasing molecules (CORMs) are a class of compounds that can release carbon monoxide (CO) and are often used in biomedical research to study the physiological and pathological effects of CO in the body.

[0054] The near-infrared fluorescent nanoprobe for detecting carbon monoxide and its preparation method and application are described in detail below in combination with examples and experimental data.

[0055] Example 1: Preparation method of near-infrared fluorescent nanoprobe for detecting carbon monoxide

[0056] 1. Preparation of lanthanide-doped upconversion nanoparticles:

[0057] 1. Preparation of NaYF 4 :Yb,Er UCNP

[0058] Add 1mmol rare earth chloride (Y:Yb:Er=80:18:2), 6mL oleic acid and 15mL 1-octadecene to a round-bottom flask in sequence, slowly stir and heat to 160°C under nitrogen protection, and keep warm for 1 hour. After the reaction is completed, cool naturally to room temperature. Slowly add 10mL sodium hydroxide-ammonium fluoride (sodium hydroxide: 0.2g, ammonium fluoride: 0.285g) methanol solution to the above reaction solution, heat to 80°C under nitrogen protection to remove methanol, then heat to 310°C under vigorous stirring conditions, and keep warm for 1 hour. After the reaction is completed, cool to room temperature, pour the reaction solution into 15mL ethanol, centrifuge, and the resulting precipitate is NaYF 4 :Yb,Er UCNP crude product. f 4 The crude Yb,Er UCNP was washed with 15 mL of ethanol / cyclohexane (5:1, V / V) for 3 times, centrifuged, and then the precipitate was dispersed in 15 mL of cyclohexane to obtain NaYF 4 :Yb,Er UCNP-cyclohexane solution, stored for future use.

[0059] 2. Preparation of oleic acid OA-conjugated upconversion nanoparticles OA-UCNP

[0060] 4 mL of oleic acid and 4 mL of 1-octadecene were added to a round-bottom flask, stirred and mixed evenly, and then 0.5 mmol of rare earth trifluoroacetate (Yb:Y:Er=80:18:2) was added. The mixture was heated to 160° C. under nitrogen protection and kept warm for 1 hour to obtain a uniform host shell precursor solution.

[0061] Add 5 mL NaYF into the round bottom flask 4 :Yb,Er UCNP-cyclohexane solution, 6mL oleic acid and 8mL 1-octadecene, heated to 90℃, cyclohexane was removed by vacuum distillation, and then the temperature was raised to 300℃, the host shell precursor solution was added dropwise to the reaction solution, and the reaction was kept warm for 1 hour. After the reaction was completed, it was cooled to room temperature, the reaction solution was poured into 15mL ethanol, centrifuged, and the resulting precipitate was the crude OA-UCNP. The crude OA-UCNP was washed with ethanol / cyclohexane (5:1, V / V) for 15mL*3, centrifuged, and then dispersed in 15mL cyclohexane to obtain NaYF 4 :Yb,Er@NaYF 4 UCNP-cyclohexane solution, stored for future use.

[0062] 3. Preparation of ligand-free upconversion nanoparticles UCNP

[0063] Add 13 mg NaYF into the round bottom flask 4 :Yb,Er@NaYF 4UCNP, 15mL ethanol, 1mL concentrated hydrochloric acid, ultrasonic treatment for 1 minute, and then centrifugation (13000rpm, 20 minutes). Repeat the treatment 3 times to obtain crude ligand-free upconversion nanoparticles. The crude ligand-free upconversion nanoparticles were washed with 15mL*3 of ethanol, centrifuged, and then dispersed in 15mL DMF and stored at 4℃ for later use.

[0064] 4. Preparation of caffeic acid CA-conjugated upconversion nanoparticles CA-UCNP

[0065] The ligand-free upconversion nanoparticles were dispersed in 2 mL of tetrahydrofuran to a concentration of 15 mg / mL, and ultrasonically treated for 1 minute to make them uniformly dispersed. Then 8 mL of caffeic acid (50 mg) tetrahydrofuran solution was added, heated to 50 ° C for 3 hours, and naturally cooled to room temperature. 200 μL of 0.2 mol / L sodium hydroxide solution was added to the above reaction solution to obtain a precipitate, which was the crude CA-UCNP. The crude CA-UCNP was washed with 30 mL*3 of ethanol, centrifuged, and then dispersed in 30 mL of DMF and stored for later use.

[0066] FT-IR images of OA-UCNP, ligand-free UCNP, and CA-UCNP are shown in Figure 2. Figure 1 As shown in the figure, it can be seen that due to the presence of methylene in oleic acid, OA-UCNP -1 and 2880cm -1 In the ligand-free UCNP, 2914 cm -1 and 2880cm -1 The absorption peak at 3431 cm is almost invisible, indicating that oleic acid has been completely removed. Compared with UCNP without ligand, CA-NCNP has a higher absorption peak at 3431 cm due to the presence of phenolic hydroxyl groups in caffeic acid. -1 and 3232cm -1 A strong absorption peak appeared at , proving that CA-UCNPs were successfully obtained.

[0067] 2. Preparation of MOF@UCNP

[0068] 2.8 mg amino-TPDC, 1.95 mg zirconium (IV) chloride, and 1.5 mL DMF were added to a round-bottom flask. After stirring and mixing, 100 μL CA-UCNP-DMF (12.5 mg mL -1 ) solution, ultrasonically for 5 minutes, and then heated to 90°C for 6 hours. After the end, centrifuge, wash three times with DMF, and store for future use.

[0069] SEM images of OA-UCNP and MOF@UCNP are shown in Figure 2As shown, it can be seen that the average diameter of OA-UCNP is 40nm; the average diameter of MOF@UCNP is 80nm, and the shell thickness is 20nm.

[0070] The energy spectrum of MOF@UCNP is shown in Figure 3 As shown, it indicates that zirconium and erbium coexist in MOF@UCNP, further proving that MOF@UCNP was successfully prepared.

[0071] 3. Preparation of R@MU (loaded with Rhp)

[0072] 2 mL of MOF@UCNP-DMF solution (1 mg mL -1 ), 2 mg Rhp, stirred at room temperature for 12 hours. After completion, wash with 5 mL*3 of water to remove excess Rhp, centrifuge to obtain a supernatant. The separated supernatant was analyzed by UV-visible-near infrared spectroscopy, and the Rhp loading content (LC) was calculated as follows: LC (%) = mass of loaded Rhp / mass of MOF@UCNP*100%.

[0073] Dynamic light scattering images of UCNP, MOF@UCNP, and R@MUP are shown in Figure 2. Figure 4 As described above, it can be seen that after Rhp encapsulation and PEG modification, the average hydrodynamic diameter has hardly changed compared with CA-UCNP and MOF@UCNP, proving that these treatment processes have no effect on the diameter of the nanoparticles.

[0074] 4. Preparation of R@MUP (addition of homobifunctional PEG modification)

[0075] 2 mg R@MU was dissolved in 2 mL water, and 2 mg SCM-PEG-SCM was added and stirred at room temperature for 12 hours. Afterwards, the mixture was centrifuged (11000 rpm), and the precipitate was washed with water, ultrasonicated, and centrifuged three times to obtain R@MUP.

[0076] FT-IR images of R@MU and R@MUP are shown in Figure 5 As shown in the figure, compared with R@MU, R@MUP has a higher peak at 1030-1120 cm due to the presence of COC in polyethylene glycol. -1 The absorption peak at is more prominent, further proving that PEG modification is successful.

[0077] The spectra of MOF@UCNP and R@MUP are compared as shown in Figure 2. Figure 6As shown, it can be seen from the UV-vis-NIR spectrum that the emission peak of MOF@UCNP is 540nm, which coincides with the characteristic absorption peak of Rhp (550nm), thus ensuring the luminescence resonance energy transfer between R@MUP and Rhp. The Rhp loading content and encapsulation efficiency calculated based on the UV-vis-NIR spectrum are 44.48% and 80.12%, respectively, which are much higher than the silica-coated UCNP system reported in the literature (Reference 1: Angew. Chem., Int. Ed. 2015, 54, 7915-7919. Reference 2: Nat. Med. 2012, 18, 1580-1585. Reference 3: ACS Appl. Mater. Interfaces 2016, 8, 11945-11953. Reference 4: ACS Nano 2017, 11, 4133-4144.)

[0078] From the upconversion luminescence spectrum, it can be seen that after loading Rhp, the luminescence intensity of R@MUP at 540nm is significantly reduced.

[0079] Example 2: In vitro cell imaging

[0080] 1. Experimental Methods

[0081] CT26 cells were inoculated with MOF@UCNP and R@MUP prepared in Example 1 for 12 hours, respectively, with MOF@UCNP as the control. After washing away MOF@UCNP and R@MUP that were not taken up by cells with PBS, different concentrations (0 μM, 50 μM, 500 μM) of CORM-2 were added, and upconversion luminescence microscopy (UCLM) was used to image R@MUP for exogenous CO in vitro.

[0082] CT26 cells were pretreated with R@MUP for 12 hours under anaerobic conditions. After washing away the R@MUP that was not taken up by the cells, acetaminophen was added and the intracellular luminescence intensity of R@MUP was observed using a confocal microscope.

[0083] 2. Experimental Results

[0084] 1. R@MUP has high stability and specificity for CO detection

[0085] The effect of relevant active substances on the selectivity of R@MUP for CO ( Figure 7 ) It can be seen that the absorbance will be significantly reduced only after the addition of exogenous CO (CORM-2); metal ions (Fe 2+ 、Zn 2+ , Ca 2+ Mg 2+ ), biomolecules (cysteine, glutathione, glucose), reactive oxygen species (H 2 O2 , OH, ClO - ) and reactive nitrogen (NO, NO 2 - ) had no significant effect on the absorbance. This indicates that R@MUP has high selectivity for CO.

[0086] From the effect of pH on the selectivity of R@MUP for CO, it can be seen that under different physiological conditions (metal ions (Na 2+ , K 2+ , Ca 2+ Mg 2+ ) and different pH values), no obvious upconversion luminescence changes were observed. Only after the addition of exogenous CO (CORM-2) did the upconversion luminescence change significantly. Due to the ligand exchange between Rhp and CO, the luminescence resonance energy transfer (LRET) effect between UCNP and Rhp was destroyed, thus leading to the upconversion recovery of the fluorescence signal, resulting in an increase in upconversion luminescence. Conversely, in the absence of CO, the upconversion fluorescence signal of R@MUP could not be restored to the same extent as in the presence of CO.

[0087] This shows that R@MUP has high stability and specificity for CO detection.

[0088] 2. R@MUP exhibits good biocompatibility in vitro

[0089] Cell viability of L02 cells and CT26 cells after treatment with different concentrations of R@MUP Figure 8 As shown, CT26 cell line was treated with 400 μg mL -1 After incubation with R@MUP, the cell survival rate was as high as 91.8% compared with the control group. In addition, R@MUP had lower cytotoxicity against L02 cells. Overall, R@MUP showed good biocompatibility in vitro.

[0090] 3. R@MUP has a good response to endogenous CO in cells

[0091] Confocal microscopy upconversion luminescence images of CT26 cells after incubation with different nanoparticles and different concentrations of CO (via CORM-2) or APAP. Fig. 9 As shown, it can be seen that compared with the control group (MOF@UCNP), under 980nm laser irradiation, the Rhp loaded in R@MUP absorbed the upconversion fluorescence of UCNP, resulting in the quenching of the upconversion fluorescence signal R@MUP.

[0092] Cells were treated with CORM-2 or acetaminophen (APAP) to produce exogenous or endogenous CO. It can be seen that with the increase of exogenous CO concentration, the upconversion fluorescence signal of R@MUP gradually increased. R@MUP also has good imaging ability for endogenous CO in hypoxic environment.

[0093] The above results indicate that R@MUP can be efficiently absorbed by cells and has good biocompatibility. It also indicates that R@MUP has a good response to endogenous CO in cells.

[0094] Example 3: Tissue Imaging

[0095] After 1 week of acclimatization, C57 mice (7 weeks) were killed and liver tissues were obtained. Liver tissue slices were treated with R@MUP (50 μg mL -1 ) were cultured at 4°C. After 12 h, the slices were washed three times with PBS to remove the residual R@MUP, and then CORM-2 (500 μM) was added and cultured for another 50 min at 37°C in the dark. The upconversion luminescence intensity of the slices after treatment was recorded by confocal microscopy.

[0096] Confocal microscopy upconversion luminescence image of mouse liver tissue sections Fig.10 As shown in the figure, it can be seen that at 540nm, the luminescence signal of the tissue slice incubated with CORM-2 is more obvious than that of the tissue slice not incubated with CORM-2. This shows that R@MUP can be applied to CO imaging of mouse liver tissue and guide CO detection in vivo.

[0097] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0098] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0099] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A near-infrared fluorescent nanoprobe for detecting carbon monoxide, characterized in that: The near-infrared fluorescent nanoprobe for detecting carbon monoxide is a core-shell nanocomposite material composed of lanthanide-doped upconversion nanoparticles as a core layer and an acid-resistant metal organic framework as a shell layer, wherein the shell layer is loaded with Rhp and the outer surface of the shell layer is modified with PEG.

2. A near-infrared fluorescent nanoprobe for detecting carbon monoxide according to claim 1, characterized in that: The average hydrodynamic diameter of the near-infrared fluorescent nanoprobe is 100-200 nm.

3. A near-infrared fluorescent nanoprobe for detecting carbon monoxide according to claim 1, characterized in that: The acid-resistant metal organic framework includes at least one of UiO-68-NH2, PCN-222, and PCN-224.

4. A near-infrared fluorescent nanoprobe for detecting carbon monoxide according to claim 1, characterized in that: The lanthanide-doped upconversion nanoparticles are NaYF4:Yb,Er@NaYF4.

5. A method for preparing a near-infrared fluorescent nanoprobe for detecting carbon monoxide according to any one of claims 1 to 4, characterized in that: The method comprises: S1, dissolving the raw material of the acid-resistant metal organic framework in an organic solvent and stirring to obtain a mixed solution; dissolving the lanthanide-doped upconversion nanoparticles in an organic solvent and adding them to the mixed solution for ultrasonic and post-heating reaction, and then centrifuging to collect the precipitate to obtain core-shell nanoparticles composed of the upconversion nanoparticles and the metal organic framework; S2, dissolving the core-shell nanoparticles composed of the upconversion nanoparticles and the acid-resistant metal organic framework in an organic solvent, adding Rhp, continuously stirring the reaction to load the acid-resistant metal organic framework with the Rhp, then washing with water, collecting the supernatant by centrifugation, and freeze-drying to obtain core-shell Rhp-loaded nanoparticles; S3, dissolving the core-shell loaded Rhp nanoparticles in water, adding the homobifunctional PEG, continuously stirring the reaction, centrifuging, collecting the precipitate, and obtaining the near-infrared fluorescent nanoprobe for detecting carbon monoxide.

6. The method according to claim 5, characterized in that: In S1, the ultrasonic time is 1-30 min, and the heating temperature is 50-150°C.

7. The method according to claim 5, characterized in that: In S3, the bifunctional PEG includes at least one of SCM-PEG-SCM, SS-PEG-SS, and GAS-PEG-GAS.

8. Use of the near-infrared fluorescent nanoprobe for detecting carbon monoxide according to any one of claims 1 to 4 in the preparation of a carbon monoxide detection product.

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