Apparatus and method for determining the chiral optical properties of semiconductor nanohelices from third-harmonic Mie scattering.

Abstract

Methods and devices are provided for detecting chiral properties from a sample. Light can be directed toward the sample in contact with the chiral nanoparticles. Third harmonic Mie scattering (THMS) optical activity generated by the chiral nanoparticles in contact with the sample can then be detected. It is contemplated that the device for detecting chiral properties of a sample further includes at least one microwell having a volume of about 1 microliter or less configured to hold chiral nanoparticles capable of generating third harmonic Mie scattering (THMS) optical activity and the sample to be analyzed. The device includes a light source configured to generate light and direct the light toward at least one microwell containing the chiral nanoparticles and the sample, and at least one detector configured to detect third harmonic Mie scattering (THMS) generated by the chiral nanoparticles in the microwell.

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 284,813, filed on December 1, 2021. The entire disclosure of the above application is incorporated herein by reference.

[0002] Government Funding This invention was made with government funding under grants HQ00342010033 and N00014-18-1-2876 awarded by the Office of Naval Research of the United States. The government holds certain rights in the invention.

[0003] The present disclosure relates to an apparatus and a method for determining chiral optical properties from third-order harmonic Mie scattering of chiral semiconductor nanoparticles. Background Art

[0004] This section provides background information related to the present disclosure that is not necessarily prior art.

[0005] Chiroptical spectroscopy brings a new optical dimension and datasets that provide additional information for the structural analysis of nanostructured particles. Determination of chiral optical properties in small volumes is an essential task in drug discovery, biomedical sequencing, biotechnology, and synthesis of materials for photonics. Although such properties can be used in robotic optimization of nanophotonic materials, these spectroscopies typically require sample volumes that are incompatible with the generation of large chemical libraries. Combinatorial nanochemistry enables the production of tens to millions of mixtures in a single process, thereby enabling the generation of large chemical libraries and the implementation of artificial intelligence algorithms.

[0006] With the advent of the rapid development of chiral nanostructures, such synthesis and analysis platforms can be applied for high-throughput determination of enzyme mimics, morphogenetic agents, antibiotics, drug delivery systems, and other applications of these bio-inspired materials. These analyses are often performed in 1,536, 3,456, or 9,600-well microplates with sample volumes as small as 1 microliter (μL), whereas traditional kill optical spectroscopy methods typically require sample volumes 100 to 1,000 times larger. Therefore, there is a need to develop novel optical tools for the rapid characterization of ultra-small volume chiral nanocompounds. Nonlinear kill optical spectroscopy potentially allows for analysis of volumes as small as tens of cubic micrometers (μm). 3 It can be observed at focal volumes up to ), and therefore is well suited to microplates containing the highest number of wells. Although nonlinear kill optical effects applicable in isotropic liquids have been reported, they are technically too complex to require combinatorial nanochemistry and high-throughput synthesis.

[0007] Therefore, realizing such methods for formats suitable for the rapid acquisition of large amounts of data is currently difficult with the current implementations of kill optical spectroscopy, as they require relatively large sample volumes and low light beams. Similar problems arise for the robotic optimization of nanophotonic materials, although these spectroscopic methods typically require sample volumes incompatible with generating large chemical libraries. Novel optical tools are needed to evaluate the chirality features of ultra-small volumes, such as 1-microliter droplets, required for high-throughput synthesis and analysis stations for chiral compounds. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] J. Yan et al., "Self-Assembly of Chiral Nanoparticles into Semiconductor Helices with Tunable near-Infrared Optical Activity", Chem.Mater.32(1), pp. 476-488 (2020) [Non-Patent Document 2] Publication (N. Gaponik et al., "Thiol-Capping of CdTe Nanocrystals: An Alternative to Organometallic Synthetic Routes", J.Phys.Chem.B, 106(29), 7177~7185(2002)) [Non-Patent Document 3] W. Feng et al., “Assembly of mesoscale helices with near-unity enantiomeric excess and light-matter interactions for chiral semiconductors”, Sci.Adv.3(3), e1601159(2017) [Non-Patent Document 4] Treharne et al., Phys.Conf.Ser., 286, 012038(2011) [Overview of the project] [Means for solving the problem]

[0009] This section provides an overall overview of this disclosure and does not constitute a comprehensive disclosure of its entire scope or all of its features.

[0010] In certain embodiments, the present disclosure relates to methods and apparatus for detecting chiral properties, and more particularly to third harmonic Mie scattering (THMS) optical activity from a sample in contact with one or more chiral nanoparticles.

[0011] In one modified form, a method is provided for detecting chiral properties from a sample. The method may include directing light toward the sample in contact with the chiral nanoparticles. The method may further include detecting the third harmonic Mie scattering (THMS) optical activity generated by the chiral nanoparticles in contact with the sample.

[0012] In one embodiment, the third harmonic Mie scattering (THMS) optical activity is circularly polarized forward third harmonic (TH) radiation.

[0013] In one embodiment, the sample has a volume of about 1 microliter or less.

[0014] In one embodiment, the sample is approximately 10 -5 It has a volume of more than a microliter and less than or equal to approximately 1 microliter.

[0015] In one embodiment, the chiral nanoparticles include semiconductor materials.

[0016] In one embodiment, the chiral nanoparticles contain cadmium tellurium (CdTe).

[0017] In one embodiment, the chiral nanoparticles include a plurality of self-assembled chiral nanoparticles that define at least one self-assembled nanostructured helix, such as a plurality of self-assembled nanostructured helices.

[0018] In one embodiment, the chiral nanoparticles include multiple chiral nanoparticles integrated together, and each chiral nanoparticle is in the form of a nanohelix having a length of about 5 micrometers or more and about 8 micrometers or less, and a thickness of about 10 nm or more and about 50 nm or less.

[0019] In one embodiment, the light is circularly polarized light.

[0020] In another variant, a device for detecting the chiral properties of a sample is provided. The device may include at least one microwell having a volume of 1 microliter or less, configured to hold chiral nanoparticles capable of generating third-harmonic Mie scattering (THMS) optical activity. At least one microwell is configured to contain the sample to be analyzed. The device further includes a light source configured to generate light and direct the light toward at least one microwell containing the chiral nanoparticles and the sample. Furthermore, the device includes at least one detector configured to detect third-harmonic Mie scattering (THMS) generated by the chiral nanoparticles in the microwell.

[0021] In one embodiment, chiral nanoparticles are provided in a sample within a microwell.

[0022] In one embodiment, chiral nanoparticles are associated with the surface of microwells.

[0023] In one embodiment, the microwells are approximately 10 -5 It has a volume of more than a microliter and less than or equal to approximately 1 microliter.

[0024] In one embodiment, the chiral nanoparticles include semiconductor materials.

[0025] In one embodiment, the chiral nanoparticles contain cadmium tellurium (CdTe).

[0026] In one embodiment, the chiral nanoparticles include a plurality of self-assembled chiral nanoparticles that define at least one self-assembled nanostructured helix, such as a plurality of self-assembled nanostructured helices.

[0027] In one embodiment, the chiral nanoparticles include multiple chiral nanoparticles integrated together. Each chiral nanoparticle is in the form of a nanohelical with a length ranging from about 5 micrometers to about 8 micrometers and a thickness of about 10 nm or more and about 50 nm or less.

[0028] In one embodiment, the light source is configured to generate circularly polarized light and guide that light.

[0029] In one embodiment, the device further includes at least one processor.

[0030] In one embodiment, at least one microwell includes an array of microwells.

[0031] Further applicable areas will become apparent from the descriptions provided herein. The descriptions and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0032] The drawings described herein are for illustrative purposes only of selected embodiments and do not represent all possible implementations, nor are they intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0033] [Figure 1A] The figure shows a CdTe nanohelix for third harmonic Mie scattering optical activity prepared according to a particular aspect of the present disclosure, and a schematic diagram of the THMS optical activity. Following illumination with left circularly polarized (LCP) light of wavelength λ, the intensity of the THMS light (λ / 3) depends on the symmetry of the CdTe nanohelix. [Figure 1B] This figure shows scanning electron micrographs (SEM) of left-handed and right-handed CdTe nanohelices prepared according to a particular aspect of the present disclosure for third-harmonic Mie scattering optical activity, and denoted as Λ-CdTe and Δ-CdTe, respectively. [Figure 1C]This figure shows a CdTe nanohelix prepared according to a particular aspect of this disclosure for third-harmonic Mie scattering optical activity, and depicts the experimental ellipticity spectrum and numerically computer-calculated differential extinction cross-section spectrum from the nanohelix in a linear optical regime. The illumination wavelength and THMS experimental detection are indicated by vertical lines. [Figure 1D] This figure shows a CdTe nanohelix for third harmonic Mie scattering optical activity prepared according to a particular aspect of this disclosure, and depicts the emission patterns from a Λ-CdTe nanohelix illuminated along its principal axis for LCP and right circularly polarized light (RCP). [Figure 1E] This diagram shows a CdTe nanohelix for third harmonic Mie scattering optical activity prepared according to a particular aspect of this disclosure, and a TH scattering setup. WP: quarter-wavelength plate, F1: optical filter allowing λ, L1: focusing lens, L2: collimating lens, F2: bandpass filter allowing only λ / 3. [Figure 2A] This shows electromagnetic simulations for CdTe nanohelices, and depicts the geometric shape of a three-dimensional (3D) nanohelix enantioma model for electromagnetic calculations. [Figure 2B] This figure shows electromagnetic simulations for CdTe nanohelices, specifically Λ-CdTe electric field profile maps calculated using the FDTD (finite difference time domain) method under full-wave (300nm to 1500nm) RCP (left) and LCP (right) illumination. [Figure 2C] This diagram shows an electromagnetic simulation for a CdTe nanohelix, illustrating the emission pattern of Λ-CdTe oriented perpendicular to the direction of electromagnetic wave incidence. The 3D emission pattern was obtained from electromagnetic waves with a wavelength of 1095 nm. [Figure 2D]This figure shows an electromagnetic simulation for a CdTe nanohelix, illustrating the two-dimensional (2D) (x-normal) radiation pattern of Λ-CdTe oriented parallel to the direction of electromagnetic wave incidence. The data was obtained by setting the reference direction, which is the direction of electromagnetic wave incidence, to -z. [Figure 2E] This figure shows an electromagnetic simulation for a CdTe nanohelix, illustrating the two-dimensional (2D) (x-normal) radiation pattern of Λ-CdTe oriented perpendicular to the direction of electromagnetic wave incidence. The data was obtained by setting the reference direction, which is the direction of electromagnetic wave incidence, to -z. [Figure 3A] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS). For LCP and RCP light, the forward third harmonic (TH) intensity (passing through the sample and relative to the light source generating the incident laser light) is shown from Λ-CdTe as a function of the incident laser output at wavelength λ=1095 nm. The symbols represent experimental data points (each being the median from 50 measurements), and the lines represent the fitting to a cubic power law. A schematic diagram of the experiment is shown as an inset. [Figure 3B] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS). For LCP and RCP light, the forward third harmonic (TH) intensity (passing through the sample and relative to the light source generating the incident laser light) is shown from Δ-CdTe as a function of the incident laser output at wavelength λ=1095 nm. The symbols represent experimental data points (each being the median from 50 measurements), and the lines represent the fitting to a cubic power law. [Figure 3C] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS), showing multiphoton forward emission from a Λ-CdTe nanohelix simultaneously with illumination at 1095 nm. The TH signal (at 365 nm) clearly dominates the near-emission wavelengths of linearly polarized LCP and RCP light. [Figure 3D]This demonstrates the optical activity of third harmonic Mie scattering (THMS), and shows the THMS ellipticity at three different wavelengths, calculated from output-dependent curves from Λ- and Δ-CdTe, as shown in Figures 3A and 3B. The kill optical response is well resolved, as demonstrated by the error bars indicating the standard deviation. [Figure 4A] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS), showing the third harmonic (TH) intensity perpendicular to the counterclockwise direction from the CdTe nanohelix (Λ-CdTe) (perpendicular to or perpendicular to the direction of the laser beam from the light source after it leaves the sample) as a function of the incident laser output at wavelength λ=1095nm for LCP and RCP light. [Figure 4B] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS), showing the THMS ellipticity at three different wavelengths, calculated from the output-dependent curves for Λ- and Δ-CdTe. The Kill optical response is well resolved, as demonstrated by the error bars (showing the standard deviation). This Kill optical response is opposite to that in Figure 3D. [Figure 4C] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS), showing the forward TH intensity (relative to the light source passing through the sample and the light source generating the laser light) as a function of analyzing the quarter-wavelength plate (AWP) rotation angle for Λ-CdTe. LCP and RCP incident light produce LCP and RCP TH light, respectively. [Figure 4D] This figure demonstrates the optical activity of third harmonic Mie scattering (THMS), showing the TH intensity in the 90° direction as a function of the AWP rotation angle for Λ-CdTe and Δ-CdTe. LCP and RCP incident light produce linearly polarized TH light. All measurements were performed with incident light at 1095 nm. A schematic diagram of the experiment is shown in the inset. [Figure 5A]This figure shows an example of the application of THMS to characterize ultra-small volume chiral nanostructures, and presents proof-of-principle data demonstrating that a method according to a particular aspect of this disclosure can clearly distinguish between Λ-CdTe and Δ-CdTe in a 1 mm thick optical cuvette (in contrast to a standard 1 cm cell). The THMS ellipticity was calculated from output-dependent curves measured at three different wavelengths. [Figure 5B] This figure demonstrates an application of THMS to evaluate the characteristics of ultra-small volume chiral nanostructures, showing that within the same 1 mm cuvette, the TH intensity follows a clear third-order dependence as a function of laser power at a wavelength of 1095 nm. Despite the small size of the cuvette, the kill optical effects for LCP and RCP, respectively, are clearly reversed in sign due to the symmetry of the sample, indicating the potential for application in very small volumes. [Figure 5C] This figure shows an example of the application of THMS to evaluate the characteristics of ultra-small volume chiral nanostructures, and is a schematic diagram illustrating an example of the application of a technique according to a particular aspect of this disclosure as an analytical tool for parallel combinatorial chemical synthesis. [Figure 5D] This figure illustrates an example of THMS application for evaluating the characteristics of ultra-small volume chiral nanostructures. It shows how high-throughput application is possible by scanning a laser beam within an optical objective lens to investigate reaction conditions in detail. The reaction conditions involve generating a nanomolar amount of the desired compound in a minute volume (e.g., <1 μL) arranged across a microplate. The red arrow indicates the direction of the incident light. [Figure 5E] This figure shows an example of the application of THMS to evaluate the characteristics of ultra-small volume chiral nanostructures, and is a schematic diagram of in-line reaction monitoring within a microreactor. [Figure 6A] The optical activity of third harmonic (TH) Mie forward scattering is shown at two wavelengths, 1065 nm and 1125 nm. The TH intensity was measured at 1065 nm as a function of the incident power to the Λ-CdTe nanohelix in a forward scattering setting (a schematic diagram of the experimental setup is included in the inset), as shown in the figure. [Figure 6B] The optical activity of third harmonic (TH) Mie forward scattering is shown at two wavelengths, 1065 nm and 1125 nm, and the TH intensity was measured at 1065 nm as a function of the incident power to the Δ-CdTe nanohelix in the forward scattering setting, as shown in the figure. [Figure 6C] This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths: 1065 nm and 1125 nm. [Figure 6D] This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths, -1065 nm and 1125 nm. [Figure 7A] This figure shows a clear emission at the third harmonic wavelength simultaneously with the emission at 1065 nm light, and as shown in the inset, it is forward multiphoton emission from a Λ-CdTe nanohelix. [Figure 7B] This figure shows the emission at 1065 nm light and the clear emission at the third harmonic wavelength simultaneously, and as shown in the inset, it is set up for right-angle scattering. [Figure 8A] The figure shows scanning electron microscopy (SEM) images of a CdTe nanoribbon at varying magnifications, demonstrating that third harmonic (TH) Mie optical activity is not observed in a comparative example of an achiral CdTe nanoribbon. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with a function of the equation y = Ax³. [Figure 8B] The figure shows scanning electron microscopy (SEM) images of a CdTe nanoribbon at varying magnifications, demonstrating that third harmonic (TH) Mie optical activity is not observed in a comparative example of an achiral CdTe nanoribbon. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with a function of the equation y = Ax³. [Figure 8C]The figure shows scanning electron microscopy (SEM) images of a CdTe nanoribbon at varying magnifications, demonstrating that third harmonic (TH) Mie optical activity is not observed in a comparative example of an achiral CdTe nanoribbon. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with a function of the equation y = Ax³. [Figure 8D] In the comparative example of an achiral CdTe nanoribbon, the absence of third harmonic (TH) Mie optical activity is shown, and the figure shows two measurement results of TH intensity as a function of incident power in a forward scattering setting. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 8E] In the comparative example of an achiral CdTe nanoribbon, the absence of third harmonic (TH) Mie optical activity is shown, and the figure shows two measurement results of TH intensity as a function of incident power in a forward scattering setting. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 8F] The example of a comparative achiral CdTe nanoribbon shows that third harmonic (TH) Mie optical activity is not observed, and the TH ellipticity calculated from the results in Figures 8D and 8E is shown. Inset: Schematic diagram of the experimental setup. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 8G]In a comparative example of an achiral CdTe nanoribbon, the absence of third harmonic (TH) Mie optical activity is shown, and the figure shows two measurements of TH intensity as a function of incident power in a 90° scattering setting. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 8H] In a comparative example of an achiral CdTe nanoribbon, the absence of third harmonic (TH) Mie optical activity is shown, and the figure shows two measurements of TH intensity as a function of incident power in a 90° scattering setting. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 8I] In the comparative example of achiral CdTe nanoribbons, the absence of third harmonic (TH) Mie optical activity is shown, and the TH ellipticity calculated from the results in Figures 8G and 8H is shown. Inset: Schematic diagram of the experimental setup. In the nonlinear experiment, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). The sample is illuminated with 1095 nm light. Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 9A] This figure shows the third harmonic super-Mie scattering optical activity in right-angle scattering, and the TH intensity is shown perpendicular to the clockwise CdTe nanohelix (Δ-CdTe) as a function of the incident laser output at wavelength (λ) = 1095 nm with respect to LCP and RCP light. [Figure 9B] This figure shows the third harmonic super-Mie scattering optical activity in right-angle scattering, and the multiphoton right-angle emission from the Λ-CdTe nanohelix is ​​shown simultaneously with 1095 nm illumination. [Figure 10A]The figure shows the optical activity in third harmonic (TH) Mie right-angle scattering at two wavelengths, a Λ-CdTe nanohelix in a right-angle scattering setting (including a schematic diagram of the experimental setup in the inset), and the TH intensity at 1065 nm measured as a function of incident power. [Figure 10B] This figure shows the optical activity in third harmonic (TH) Mie right-angle scattering at two wavelengths, the Δ-CdTe nanohelix in the right-angle scattering setting, and the TH intensity at 1065 nm measured as a function of incident power. [Figure 10C] This figure shows the optical activity in third harmonic (TH) Mie right-angle scattering at two wavelengths, and similar measurement results at 1125 nm have been presented for Λ-CdTe. [Figure 10D] This figure shows the optical activity in third harmonic (TH) Mie right-angle scattering at two wavelengths, and similar measurement results at 1125 nm have been presented for Δ-CdTe. [Figure 11A] This figure shows THMS polarization, and the forward TH intensity is shown as a function of the rotation angle of the quarter-wavelength plate (AWP) relative to Δ-CdTe. LCP and RCP incident light produce LCP and RCP TH light, respectively. [Figure 11B] This figure shows THMS polarization, where the TH intensity in the 90° direction is shown as a function of the AWP rotation angle relative to Δ-CdTe. [Figure 12] This figure shows the multipolar spectral decomposition of the nanohelix scattering cross section. The curves correspond to the electric dipole (ED), magnetic dipole (MD), electric quadrupole (EQ), magnetic quadrupole (QD), and total scattering cross section, simultaneously with illumination by right- and left-circularly polarized light (LCP and RCP, respectively). The circular difference (CD) corresponds to the difference (Δ) in the scattering cross section. [Figure 13A]This figure shows the third harmonic (TH) scattering in a liquid medium containing 0.2% sodium dodecyl sulfate (SDS), and the TH intensity as a function of incident laser power for 0.2% SDS illuminated with left-circularly polarized (LCP) and right-circularly polarized (RCP) light. The inset shows a schematic diagram of the setup for measuring TH forward emission. In the plot, the sample was illuminated with 1095 nm light. The line is fitted to y = Ax + B. [Figure 13B] This figure shows the third harmonic (TH) scattering in a liquid medium containing 0.2% sodium dodecyl sulfate (SDS), and the TH intensity as a function of incident laser power for 0.2% SDS illuminated by LCP and RCP light. The inset shows a schematic diagram of the setup for measuring TH emission at a right angle. In the plot, the sample was illuminated with 1095 nm light. The line is fitted to y = Ax + B. [Figure 14A] This figure shows how to determine whether third harmonic (TH) light originates from a 10 mm cuvette interface. The TH intensity is shown as a function of the focus lens position for illumination with linear and left-circularly polarized (LCP) 1095 nm light (incident power = 15 mW). The position of the cuvette containing Λ-CdTe was fixed. Measurements were performed using the forward scattering geometry. [Figure 14B] This figure shows how to determine whether third harmonic (TH) light originates from a 10 mm cuvette interface. The TH intensity is shown as a function of the incident power, measured for an empty cuvette with a forward scattering geometry. The focusing lens was positioned at 89.5 mm. The line is fitted to y = Ax + B. [Figure 15A] This figure shows that the third harmonic (TH) optical rotation is not observed. A schematic diagram of the setup is also shown. [Figure 15B] This figure shows that no third harmonic (TH) optical rotation is observed. The TH intensity is shown as a function of the analyzer angle (distinguishing between Λ-CdTe and Δ-CdTe) for both chiral morphologies of nanoparticles prepared according to this disclosure. [Figure 16]The figure shows the absence of third harmonic (TH) light from the 1 mm cuvette interface, and more specifically, the TH intensity as a function of the position of the focus lens for illumination with linear and left circularly polarized (LCP) 1095 nm light (incident power = 15 mW). The measurement was performed using the forward scattering geometry. [Figure 17A] This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths when a sample was measured in a cuvette with a path length of 1 mm. TH intensity was measured at 1065 nm as a function of incident power to a Λ-CdTe nanohelix in a forward scattering setting. In this measurement, the incident light was either left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 17B] This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths when a sample was measured in a cuvette with a path length of 1 mm. TH intensity was measured at 1065 nm as a function of incident power to a Δ-CdTe nanohelix in a forward scattering setting. In this measurement, the incident light was either left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 17C] This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths when the sample was measured in a cuvette with a path length of 1 mm. Similar measurement results at 1125 nm have been presented for Λ-CdTe. In this measurement, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Figure 17D]This figure shows the optical activity of third harmonic (TH) Mie forward scattering at two wavelengths when a sample was measured in a cuvette with a path length of 1 mm. Similar measurement results at 1125 nm are presented for Δ-CdTe. In this measurement, the incident light is left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is fitted with the function y = Ax³. [Modes for carrying out the invention]

[0034] The corresponding reference numbers indicate the corresponding parts across several figures in the drawing.

[0035] Example embodiments are provided so that the present disclosure may be complete and fully convey its scope to those skilled in the art. Many specific details, such as examples of particular compositions, components, apparatus, and methods, are specified to enable a full understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that certain details are not required, that the example embodiments may be embodied in many different forms, and that none of these should be construed as limiting the scope of the present disclosure. In some example embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0036] The terminology used herein is intended solely to describe and not limit to embodiments of a particular example. When used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural form unless the context explicitly indicates otherwise. The terms “equip,” “contain,” and “have” are inclusive and thus indicate the presence of the described feature, element, composition, step, integer, operation, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The open-ended term “equip” should be understood as a non-restrictive term used to describe and claim various embodiments in a particular aspect described herein, although it may also be understood as, alternatively, a more restrictive and limiting term such as “consist of” or “essentially consist of.” Accordingly, for any given embodiment describing a composition, material, component, element, feature, integer, operation, and / or process step, the Disclosure more explicitly includes embodiments consisting of or essentially consisting of such described composition, material, component, element, feature, integer, operation, and / or process step. In the case of “consisting of,” the alternative embodiment excludes any additional composition, material, component, element, feature, integer, operation, and / or process step, while in the case of “essentially consisting of,” any additional composition, material, component, element, feature, integer, operation, and / or process step affecting a materially fundamental and novel property is excluded from such embodiment, but any composition, material, component, element, feature, integer, operation, and / or process step that does not affect a materially fundamental and novel property may be included in that embodiment.

[0037] Any method steps, processes, and operations described herein should not be construed as necessarily requiring implementation in a specific order discussed or described, unless specifically designated as such. It should be further understood that additional or alternative steps may be used, unless otherwise indicated.

[0038] When a component, element, or layer is said to be "on top of," "engaged to," "connected to," or "bonded to" another element or layer, it may be directly on top of, engaged to, connected to, or bonded to the other component, element, or layer, or there may be an intervening element or layer. In contrast, when an element is said to be "directly on top of," "directly engaged to," "directly connected to," or "directly bonded to" another element or layer, there may be no intervening element or layer. Other words used to describe the relationships between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent"). As used herein, the term "and / or" includes any and all combinations of one or more of the related enumerated items.

[0039] Although terms such as "first," "second," and "third" may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise indicated. These terms may be used solely to distinguish one step, element, component, region, layer, or section from another. Terms such as "first," "second," and other numerical terms, when used herein, do not imply arrangement or order unless explicitly indicated by the context. Thus, a first step, element, component, region, layer, or section discussed below may be referred to as a second step, element, component, region, layer, or section without departing from the teaching of the example embodiments.

[0040] Spatial or temporally relative terms such as "before," "after," "inside," "outside," "below," "below," "above," and "upper" may be used herein to describe the relationship of one element or feature to another element or feature(s), as shown in the drawings, for the sake of clarity. Spatial or temporally relative terms may also be intended to encompass different orientations of the device or system during use or operation, in addition to the orientations depicted in the drawings.

[0041] Throughout this disclosure, numerical values ​​represent approximate magnitudes or limits of range to encompass minute deviations from a given value, embodiments having the approximate value mentioned, and embodiments having the exact value mentioned. Except in the operational examples provided at the end of the modes for carrying out the invention, all numerical values ​​of parameters (e.g., quantities or conditions) in this specification, including the appended claims, should be understood to be modified in all examples by the term “about,” whether or not “about” actually precedes the numerical value. “About” indicates that the stated numerical value allows for some degree of ambiguity (somewhat close to the exact value; roughly or fairly close to the value; approximately). Where the ambiguity realized by “about” is not understood in the art in this ordinary sense in other cases, “about” as used herein indicates at least the variability that may arise from the ordinary methods of measuring and using such parameters. For example, "approximately" may include variations of 5% or less, 4% or less (optional), 3% or less (optional), 2% or less (optional), 1% or less (optional), 0.5% or less (optional), and, in certain aspects, 0.1% or less (optional).

[0042] Furthermore, the disclosure of the range includes the disclosure of all values ​​within the entire range, including the endpoints and subranges given to the range, as well as the disclosure of further divided ranges.

[0043] Here, the example embodiment will be described in more detail with reference to the attached drawings.

[0044] In various embodiments, this disclosure intends to describe the use of novel kill optical effects in certain chiral nanoparticle structures that can be used particularly for characterizing small volume samples, for example, samples with a volume of approximately 1 microliter (μL) or less. In certain embodiments, the sample volume is 10 -5The volume may be as small as a μL. Therefore, nonlinear kill optical characterization of small-volume inorganic nanostructures is intended by using circularly polarized Mie scattering spectroscopy. Light is a TEM wave, but natural light is generally unpolarized, and all planes of propagation have equal probability. Generally, circularly polarized light (CPL) typically has two perpendicular electromagnetic waves with equal amplitude and a phase difference of 90°, and can have either left-handed orientation (the electric vector of the light emanating from the source appears to rotate clockwise) or right-handed orientation (the electric vector of the light emanating from the source appears to rotate counterclockwise). Elliptically polarized light is light with two perpendicular waves of unequal amplitude differing by only 90° in phase, and can be used similarly to circularly polarized light.

[0045] The chirality of nanoparticles refers to the asymmetrical optical activity of nanoparticles or nanostructures having different symmetries: clockwise to form left-handed chirality (S, L, or Λ orientation) and counterclockwise to form right-handed chirality (R, D, or Δ orientation). Nanoparticles can be supplied, for example, in a mixture with an enantiomatous purity of approximately 99% or more of either left (Λ) or right (Δ) symmetry of enantiomatous nanoparticle species, or, optionally, in a relatively pure enantiomatous mixture having an enantiomatous purity of 99.5% or more. The nanoparticle component(s) is a dispersion of preferably chiral nanoparticles(s) in a liquid medium such as an aqueous medium. Such nanoparticle dispersions are preferably stable under environmental conditions.

[0046] "Nanoparticles" are solid or semi-solid materials that may have various shapes or forms and may include nanostructures or aggregates of nanoparticles. However, it will be understood by those skilled in the art that nanoparticles generally mean that the particles / structures have at least one spatial dimension of about 10 micrometers (μm) (10,000 nm) or less. In certain embodiments, nanoparticles have at least one spatial dimension, such as thickness or diameter, which is about 2 nm to about 5 μm, optionally about 2 nm to about 3 μm, optionally about 2 nm to about 1 μm, optionally about 2 nm to about 500 nm, optionally about 2 nm to about 100 nm, optionally about 2 nm to about 50 nm, optionally about 5 nm to about 30 nm, and optionally about 25 nm with certain variability. It should be noted that other dimensions may be larger than these ranges. In certain embodiments, the nanoparticles used by this disclosure are nanohelices, nanoribbons, nanorods, or any nanoaggregates of these nanoparticles. In certain embodiments, chiral nanoparticles are nanoassemblies of nanohelices or nanoribbons, such as aggregates of nanostructured helices.

[0047] Therefore, chiral nanoparticles may include or be formed from light-absorbing materials. Chiral nanoparticles may also include semiconductor materials, including direct and indirect bandgap semiconductors. In certain embodiments, chiral nanoparticles formed according to certain embodiments of the present disclosure are selected from the group consisting of CdTe, CdSe, CdS, gold, silver, copper, nickel, iron, carbon, platinum, silicon, HgTe, HgSe, HgS, PbTe, PbSe, PbS, MoS2, FeS2, FeS, FeSe, and combinations thereof. In further embodiments, chiral nanoparticles include semiconductor materials such as cadmium tellurium (CdTe).

[0048] In various embodiments, methods for experimentally examining the chiral optical properties of ultrasmall volumes of chiral nanoscale particles using third-harmonic Mie scattering (THMS) are provided according to this disclosure. THMS optical activity occurs when three circularly polarized photons at the fundamental frequency produce a single photon at three times the frequency. More specifically, in certain embodiments, the method can use third-harmonic Mie scattering (THMS) optical activity observed in a suspension of CdTe nanostructured helices in a volume several orders of magnitude smaller than 1 μL. As described herein, when CdTe helices were illuminated with laser beams having wavelengths of 1065 nm, 1095 nm, and 1125 nm, chiral optical third-harmonic emission was recorded, and the THMS intensity was approximately 10 times higher in the forward direction (progressing in the direction from the laser source) than in the lateral direction. The third-harmonic ellipticity was approximately 3°. This is thought to be due to the effect of interference between chiral and achiral effective nonlinear sensitive tensor components. THMS for semiconductor helices according to certain aspects of this disclosure is, for example, from a volume of about 1 microliter or less to 10 -5 It provides rapid, high-throughput kill optical feature evaluation of sample volumes down to as small as μL.

[0049] Furthermore, as with the background technology, there is a need to develop new optical tools for the rapid characterization of ultra-small volume chiral nanocompounds. Nonlinear kill optical spectroscopy has the potential to handle volumes as small as tens of cubic micrometers (μm). 3 It can be observed at focal volumes up to ) and is well suited to microplates containing the highest number of wells. Nonlinear kill optical effects applicable in isotropic liquids have been reported, but they are technically too complex to require combinatorial nanochemistry and high-throughput synthesis. For example, in the case of the optical activity of super-Rayleigh scattering, the geometry of the well plate is not favorable for nonlinear Rayleigh scattering registration, and therefore a 4π integrating sphere centered on each sample is typically required to reduce artifacts and crosstalk between adjacent samples.

[0050] Nonlinear kill-optical characterization of small-volume inorganic nanostructures may be possible by circularly polarized Mie scattering spectroscopy. This scattering modality is advantageous over Rayleigh scattering because Mie scattering occurs within a small continuous angle. The smaller scattering continuity angle simplifies the registration and polarization analysis of scattered photons and conforms to the requirements of microplate geometry. Mie scattering from chiral metallic particles and their aggregates can exceptionally result in a strong dependence of light polarization, torque transfer, and spin-polarized electron emission. Despite the broad interest attracted by chiral nonmetallic particles in relation to ultrafast and miniaturized devices, their Mie scattering properties are not well known. Interactions between light materials and nonmetallic particles can involve electrical and magnetic dipoles and multipoles, as well as anapol resonances. Compared to plasmonic equivalents, the electrical and magnetic contributions in these nonmetallic nanoparticles can become comparable, thereby resulting in enhanced kill-optical properties. The nonlinear kill-optical properties of such individual particles are currently unknown.

[0051] In connection with this disclosure, the nonlinear scattering process of CdTe semiconductor helices is explored, and novel kill optical effects that can be used to characterize samples of interest, particularly very small sample sizes (e.g., volumes of about 1 microliter (μL) or less), are discovered and demonstrated. In certain embodiments, the nanoparticles are CdTe nanoparticles that form self-assembled nanostructured helices. The length of the nanostructured helices may be about 5 to about 8 micrometers (μm), thereby resulting in Mie scattering. For brevity, these nanoparticles will be referred to as nanohelices, because they not only exhibit some nanoscale dimensions (e.g., having a thickness of approximately 25 nm), but also largely retain the nanoscale dimensions of individual self-assembled, woven nanowires. Semiconductor nanohelices can be obtained with 99.5% enantioma purity in both left (Λ) and right (Δ) symmetry. The semiconductor nanohelices are randomly dispersed in an isotropic liquid environment in all samples described herein. These dispersions reveal strong Kill Optical third harmonic Mie scattering (THMS) observed at three different wavelengths in the near-infrared region of the electromagnetic spectrum.

[0052] The THMS of a nanohelix is ​​characterized by approximately 10 times stronger third harmonic (TH) emission in the forward direction than at a 90° angle to the incident light. The nonlinear ellipticity can be set to a height corresponding to 3°, thereby changing the sign for Λ and Δ-CdTe nanohelices. The kill optical contrast is inverted between forward emission and emission at a 90° angle, thereby revealing the phase relationship between the TH-sensitive chiral effective tensor component and the achiral effective tensor component. Furthermore, the kill optical effect can be observed in both circularly polarized TH light of forward emission and linearly polarized TH light of transverse emission. Finally, successful kill optical characterization of CdTe nanohelices is demonstrated in micro (<1 μL) volumes using THMS.

[0053] As described above, referring to Figures 1A-1E, THMS optical activity arises when three circularly polarized photons at the fundamental frequency produce a single photon at three times the frequency, with a conversion efficiency that depends on the chirality of the CdTe helix and the symmetry of the incident circularly polarized light, as shown in Figure 1A. This effect is the manifestation of optical activity in the general sense of the term, and in this case, for example, it represents any change in the intensity or polarization of light due to the chirality of the material. Prior to the present invention, it is believed that THMS optical activity has never been previously observed for any semiconductor, metal, dielectric, or biological sample.

[0054] As described in the example below, CdTe nanohelices can be synthesized using the method described in J. Yan et al., "Self-Assembly of Chiral Nanoparticles into Semiconductor Helices with Tunable near-Infrared Optical Activity," Chem. Mater. 32(1), pp. 476-488 (2020), the relevant parts of which are incorporated herein by reference, and create a helicoid shape by a geometry approaching that of a twisted ribbon. Analysis of SEM microscopy images and geometric parameters of the nanohelices (140±20 nm thick, 453±70 nm wide, and 302±45 nm pitch in one batch) suggests that their uniformity arises from a self-limiting assembly of nanoparticles controlled by electrostatic repulsion. Referring further to Figure 2A, the width, thickness, and pitch of the nanohelix are shown (the thickness is 25 nm, and the pitch is approximately 550 nm, from the first vertex of the first twist to the second vertex of the adjacent twist). The circular dichroism (CD) spectra of the Λ- and Δ nanohelices have two similar singular shapes, although with opposite polarities. The differential extinction cross-section spectra of the 3D helix model calculated by the time-domain finite difference (FDTD) method (Figures 2B-2E) agree well with the experimental CD spectra (Figure 1C). The difference in amplitude of the experimental CD peaks is due to the difference in concentration of the prepared suspensions. Figure 1D shows the scattering patterns of the Λ-CdTe nanohelix at the same wavelength as the incident beam illuminating along the principal axis for LCP and RCP light (further details on these simulations can be found in Figures 2A-2E). Clearly, the patterns are characteristic of Mie scattering.

[0055] CdTe nanohelices exhibit multiple scales in their structure, including microscale lengths comparable to visible and near-infrared wavelengths and submicron scale pitch lengths, making them a useful candidate not only for observing linear kill optical activity during scattering but also for observing super-Mie scattering rather than super-Rayleigh scattering. To evaluate super-Mie scattering activity, a TH experimental setup is shown in Figure 1E, which includes a laser light source, chopper, polarizer, various lenses (specified L) and filters (specified F), as well as a sample for testing in a cuvette containing CdTe. TH-scattered light was measured both forward and perpendicular to the direction of the incident light. Briefly, femtosecond laser pulses at wavelengths of 1065 nm, 1095 nm, and 1125 nm were circularly polarized by an achromatic quarter-wavelength plate and focused into a cuvette made of quartz glass containing an aqueous dispersion of CdTe nanohelices. The scattered light is then collimated and filtered to select only the TH wavelength, as described in the example.

[0056] Examples Example A All chemicals used in this embodiment are of analytical grade or the highest purity available. Aluminum telluride (Al2Te3), used as the source of hydrogen telluride gas, was purchased from Materion (product number: 122704). Cadmium perchlorate hexahydrate was purchased from Alfa Aesar (product number: 12936). L- and D-cysteine ​​hydrochloride monohydrates (product numbers: C7880 and C8005, respectively), thioglycolic acid (product number: 528056), sodium hydroxide (NaOH), hydrochloric acid (HCl), and methanol were purchased from Sigma Aldrich. Deionized water (DI water) was prepared using a Milli-Q water purification system (Millipore).

[0057] Cadmium telluride nanoparticles (CdTe NPs) were synthesized by following a method from a previous publication (N. Gaponik et al., "Thiol-Capping of CdTe Nanocrystals: An Alternative to Organometallic Synthetic Routes," J. Phys. Chem. B, 106(29), 7177-7185 (2002)) (the relevant portion of this publication is incorporated herein by reference with some modifications). For chiral CdTe NPs, aqueous solutions of a mixture of cadmium perchlorate hexahydrate (Cd(ClO4)2·6H2O) and L- or D-cysteine ​​(L- / D-Cys) hydrochloride monohydrate were prepared in 125 mL of deionized water (DI water) at final concentrations of 18.75 mM and 45 mM. Next, the pH of the mixed solution was adjusted to 11.2 by adding 1 M sodium hydroxide (NaOH). The mixed solution was placed in a 250 mL three-necked round-bottom flask and connected to another 50 mL three-necked round-bottom flask containing 0.1 g of aluminum telluride powder (Al2Te). These synthesis reaction vessels were purged with nitrogen gas for 30 minutes while being vigorously stirred to ensure thorough mixing of the solutions.

[0058] Hydrogen telluride gas was generated by introducing 0.5 M hydrogen sulfide into a small flask containing Al2Te powder and slowly purging it into a mixed solution of cadmium precursor and ligand. The solution was then refluxed under nitrogen purging for approximately 10 hours to obtain chiral CdTe NPs.

[0059] Achiral CdTe NPs were prepared according to the same method described above, but by using thioglycolic acid (TGA) as the surface ligand source (18.75 mM) for the cadmium precursor mixture solution. After slowly purging with hydrogen telluride gas, the solution was refluxed for 1 hour. The resulting NP dispersion was stored in dark bottles before the accumulation step, which included aging requirements as described below.

[0060] Example B A colloid of CdTe nanohelices and achiral CdTe nanoribbons is prepared in this example. The self-assembly of the nanohelices is as follows: CdTe NPs supporting L- or D-Cys, as described in Example A, were assembled into helical structures by the modified methods described above in J. Yan et al., Chem. Mater. 32, p. 476 (2020) and W. Feng et al., "Assembly of mesoscale helices with near-unity enantiomeric excess and light-matter interactions for chiral semiconductors," Sci. Adv. 3(3), e1601159 (2017) (the relevant parts of these are incorporated herein by reference). The dispersion of synthesized chiral CdTe NPs was aged at room temperature in the dark for 3 to 5 days prior to self-assembly. 20 μL of 0.1 M Cd(ClO4)2·6H2O was injected into 500 μL of aged chiral NP, and the pH was adjusted to 8 with 1 M hydrochloric acid solution. In some batches, the solution was then mixed with 1 mL or 1.5 mL of methanol and maintained under room light conditions for 3 days. The self-accumulating colloid was centrifuged at 6,000 rpm for 3 minutes, and the black precipitate was redispersed in DI water. The resulting solution was treated three times with the same washing process to ensure that purified nanohelix colloid was obtained. To avoid nanohelix aggregation, the final precipitate was redispersed in a 0.05 wt% sodium dodecyl sulfate (SDS) solution and sonicated for approximately 1 minute.

[0061] The self-assembly of achiral nanoribbons was as follows: CdTe NPs coated with TGA were assembled into achiral nanoribbons by modifying the method described above for nanohelix assemblies. Without adding Cd(ClO4)2·6H2O, the pH of 500 μL of aged TGA-CdTe NPs was directly adjusted to 8 with a 1 M hydrochloric acid solution, mixed with 1.5 mL of methanol, and maintained under room light conditions for 3 days. The nanoribbon solution, treated in the same washing process as the nanohelix, was redispersed in a 0.05 wt% SDS solution and sonicated for approximately 1 minute.

[0062] Example C The characterization of nanoparticle aggregates is explored in this example, as seen in the CdTe nanohelices and achiral CdTe nanoribbons of Example B.

[0063] Linear optical characterization. Suspensions of CdTe nanohelices in quartz glass cuvettes were characterized in an applied photoelectronic physics Kirascan CD spectrometer. Two photomultiplier tubes (PMTs) were used as detectors, each designed for measurements in different spectral regions. The measured CD spectrum of a reference sample (cuvette containing 0.2% SDS) was extracted from the spectra of the samples investigated. The path length in the cuvette was 10 mm. The time per point was set to 0.5 s, and the step was set to 1 nm. Each spectrum was measured three times before averaging. The bandwidth was set to 2 nm in the 300–600 nm spectral region and to 40 nm in the 600–1130 nm region.

[0064] The nonlinear experiment was conducted as follows: A Radiantis Inspire optical parametric oscillator (OPO), propelled by a Ti:sapphire laser, was used as the laser source for the nonlinear experiment. Laser pulses were produced by the OPO at an iteration rate of 80 MHz and had a width of 200 fs. An optical chopper with a 50% duty cycle tuned the laser beam to a frequency of 246 Hz. An achromatic half-wavelength plate, designed to function within the spectral range of 690–1200 nm, was placed in front of an uncoated Glan-Laser calcite polarizer to achieve output control. After passing through the polarizer (with the transmission axis oriented vertically), an achromatic quarter-wavelength plate (with a design wavelength range of 690–1200 nm) controlled the polarization state of the laser beam. Left-circularly polarized light was defined to appear along the direction of propagation from the source's perspective, such that the electric field of the light traces a helix in space that rotates and propagates in the direction of positive trigonometric functions. A pair of long-pass filters removed light with wavelengths lower than the filter's cut-on wavelength (1000 nm) from the beam. A coated achromatic double lens (designed wavelength range 1050–1700 nm, focal length 30 mm) focused the beam into a quartz glass cuvette containing the sample.

[0065] In experiments measuring scattering at right angles, an anti-reflective coated 25.4-mm lens was used to focus the scattered light. Another anti-reflective coated lens (focal length 200nm) focused the focused light onto the PMT's photocathode. In experiments conducted in transmission geometry, a 25.4-mm focal length lens was placed behind the cuvette, followed by a tinted glass bandpass filter (transmission in the 335-610nm region), a 3UV-reinforced Al mirror, and a 200-mm focal length lens to focus the light onto the PMT's photoelectrode.

[0066] To investigate the polarization of THMS light, a superachromatic quarter-wavelength plate (designed wavelength range 325–1100 nm) and an uncoated Glan-Laser calcite polarizer were added to the experimental setup.

[0067] In all experiments, a hard-coated bandpass filter with a full width at half maximum of 10 nm was placed in front of the detector to separate scattered light within the desired wavelength range. The signal from the PMT was pre-amplified five times before entering the photon counter. The photon counter was used in a gated regime, and the signal was measured over a uniform time period with the laser beam being blocked and unblocked by an optical chopper to obtain an evaluation of noise and environmental counts.

[0068] Electromagnetic simulations were performed as follows. To computer-calculate the linear optical activity of the CdTe nanohelix, a three-dimensional CdTe nanohelix structure was modeled, and Maxwell's equations were solved using two different techniques. The range of geometric parameters (pitch, width, and thickness) and the three-dimensional CdTe nanohelix model structure shown in Figure 2A were determined based on electron microscope images (Figure 1B). The model structure was placed in a dielectric medium with a refractive index equal to 1.33, representing water for the colloidal sample. The refractive index for CdTe was taken from the document by Treharne et al., Phys.Conf.Ser., 286, 012038 (2011) (this relevant portion is incorporated herein by reference). Thanks to a simple implementation of the time-domain finite difference (FDTD) technique as a full-wavelength solver, the spectra for the kill optical activity of the CdTe nanohelix were calculated using the commercially available software package Lumerical. Two linearly polarized total-field scattered-field (TFSF) sources perpendicular to each other were used to generate CPL by setting a uniform amplitude and having a phase difference of 90° (or -90°).

[0069] The FDTD simulation region was defined by a larger box monitor with a fully stretched coordinate matching layer and a non-uniform mesh type. Focusing tests were performed with different mesh sizes to determine the best balance between computational time constraints and simulation accuracy. Frequency profiles and cinematic monitors were inserted into the entire field region to calculate electric field enhancement in 2D. Absorption and scattering cross-sections of the model structure under opposing CPLs were acquired by two analysis groups using box output monitors, and the difference in complete extinction cross-sections (sum of absorption and scattering cross-sections) was calculated for comparison with the ellipticity observed in experimental spectra. The nanohelix model was rotated along the Cartesian axis in 45° steps to treat the random orientation of the object as colloidal dispersion. Calculations were performed for nanohelices of various widths (50, 150, and 350 nm) to account for variations in the geometric parameters of the internal object due to sharpening the edges of the nanohelix, and the resulting spectra were averaged.

[0070] The differential extinction cross-section of the nanohelix model agrees well with experimental observations. See Figure 1C. The 2D (x-normal) electric field profiles for Λ-CdTe oriented parallel to the incident direction of right-circularly polarized (RCP) and left-circularly polarized (LCP) light sources clearly demonstrate the different interactions of the model with waves of opposite polarity (Figure 2B). Movies of Λ-CdTe oriented parallel or perpendicularly reveal information about the electric and magnetic field distributions under inverse CPL.

[0071] To further investigate the optical activity of the nanohelix model at three different excitation wavelengths (1065 nm, 1095 nm, and 1125 nm), the frequency domain form of Maxwell's equations is solved by the finite element method using the COMSOL Multiphysics 5.5 software package (radio frequency module). The emission patterns for both nanohelix models oriented perpendicular and parallel to the direction of light propagation exhibited typical Mie scattering behavior (Figures 2C-2E).

[0072] Third harmonic (TH) scattering is gaining increasing applications as a fast and sensitive method for screening second hyperpolarization states. Due to their strong forward directionality, the reduction to these examples clearly indicates a Mie scattering process, rather than Rayleigh scattering. Computer models demonstrate that radiation patterns from CdTe nanohelices of the same geometric scale exhibit typical Mie scattering behavior for electromagnetic waves with all three excitation wavelengths (Figures 2C-2F). By accurately considering the different scattering contributions, further agreement between the calculated CD spectrum and the experimental CD spectrum is obtained (Figure 1C). Multiple polarity decomposition of the linear optical spectrum (Figure 12) shows that for circularly polarized excitations, electric and magnetic dipole and quadrupole resonances can exist at both the fundamental and third harmonic wavelengths. The spectral locations of these resonances depend on the direction of incident light for each helix, and since the particles are freely rotating, all are accessible. As demonstrated in Figure 4B, the circularly polarized fundamental light produces a circularly polarized third harmonic signal. Therefore, it is reasonable to consider the nonlinear transformation process as an energy-coupled channel between the resonances identified in Figure 12, both at the fundamental and third harmonic levels.

[0073] We are cautious about attributing the physical properties of the observed optical phenomenon to THMS, and other competing mechanisms are being explored. One possibility is that the result here is due to TH generation (THG) rather than Mie scattering. Both effects are coherent, and both effects would produce strong forward radiation. Furthermore, the THG, followed by the linear optical scattering process by the nanohelix, directs a small amount of light perpendicularly, which could explain the large difference in intensity between Figures 3A-3D and 4A-4B. However, THG is not possible in an isotropic medium using circularly polarized light. One reason is that, while focusing a Gaussian beam in an isotropic medium, as a result of the Guy phase shift, the THG on one side of the focal point cancels out the THG on the opposite side through destructive interference. Another reason is that, in the case of CPL, the axial spin angular momentum of each photon (depending on the direction of the CPL) [Num.]] As such. For THG, there are three incident photons, so the total angular momentum is [Num.]] . However, a single outgoing photon has [Num.]] can only have values between. Therefore, in an isotropic medium such as the liquid environment used herein, conservation of angular momentum forces THG for CPL illumination to be impossible in the forward direction.

[0074] Furthermore, any THG from the solvent or from the glass interface can be excluded, as demonstrated in FIGS. 13A-13B and 14A-14B, respectively. Furthermore, THG followed by linear optical Mie scattering should have had the same sign as the measured ellipticity (in FIGS. 3D and 4B), which is clearly not the case. Furthermore, THG followed by a linear chiro-optical effect such as CD should further have been able to exhibit optical rotation. As discussed in more detail below, the sample was illuminated with linearly polarized light and tested for any such optical rotation, and none was found. See FIGS. 15A-15B. THG can be excluded, and furthermore, FIGS. 3C and 4C demonstrate the absence of any competing multiphoton luminescence or supercontinuum effects.

[0075] Mie scattering occurs on the scale between point scatterers (Rayleigh scattering) and geometric optics. On the microscopic scale, the dielectric dipole moment is μ i =α ij E j +β ijk E j E k +γ ijkl Ej E k E l +··· (2) It can be written as follows: However, i, j, k, and l may represent any of the Cartesian directions in the x, y, and z coordinate systems of the helix, α is the polarization tensor, β is the first hyperpolarization tensor, γ is the second hyperpolarization tensor, E j is the electric field component at the fundamental frequency of light along the j-Cartesian direction in a helix coordinate system (which can take x, y, or z values). Therefore, the dielectric dipole moment per unit volume at TH is: P I (3ω=χ) IJKL E J (ω)E K (ω)E L (ω) (3) It can be written as follows: However, χ IJKL This represents the macroscopic third-order sensitivity, where I, J, K, and L represent one of the Cartesian directions in the laboratory's X, Y, Z coordinate system (Figure 1D). Representations at microscopic and macroscopic scales are as follows:

number

[0076] In isotropic chiral media such as enantiopurine suspensions of nanohelices, χ IJKL It is non-zero. The isotropic chiral symmetry group belongs to one of the seven Curie limit groups for anisotropic materials. It is represented by ∞∞ in Hermann-Morgan, ∞ / ∞ in Shubnikov, K in Schoenfries, and ∞ / ∞² in international notation. It has three independent tensor components χ IIJJ , χIJJI , χ IJIJ They have, and they are χ IIII =χ IIJJ +χ IJJI +χ IJIJ They are related by the following, where indices I and J can take on any of the Lab Frame coordinates X, Y, or Z, but I ≠ J.

[0077] Next, the intensity at TH is, I(3ω)∝N〈|χ THS | 2 > I 3 (ω) (4) That is the case. Generally, in forward X detection, the TH scattering intensity is <|χ THS | 2 >=<|χ ZJKL | 2 > + <|χ YJKL | 2 >, however, for CPL incident light, J, K, and L can be either Y or Z, and not X. In an isotropic chiral medium, <|χ ZJKL | 2 > and <|χ YJKL | 2 Both sides have tensor components, and therefore TH polarization is possible along both Z and Y, which results in the TH intensity observed in Figure 4C, and the CPL TH light has both Z and Y components.

[0078] In contrast, in the Y direction (perpendicular to the incident beam), <|χ THS | 2 >=<|χ XJKL | 2 > + <|χ ZJKL | 2 > However, for CPL illumination, J, K, and L can take on Y or Z values ​​instead of X. As a result, in an isotropic chiral medium, <|χ ZJKL | 2 Only the ">" term can contribute, which means that TH can be polarized only vertically, as can be seen in Figure 4D.

[0079] Next, we consider the microscopic hyperpolarization state. The symmetry group of the nanohelix is ​​D2 in Schoenfries notation and 222 in Hermann-Morgan notation. It has 21 independent tensor components, 3 of which have equal indices and 18 which have equal indices in pairs. μ in the laboratory coordinate system X, Y, Z i To express angle

number

number

number

number

number

number

number

number

[0080] therefore,

number

[0081] Similar values ​​can be calculated for other macroscopic sensitivities. However, there are 21 microscopic hyperpolarity tensor elements, each of which is complex, so the number of parameters is too large to be intuitively understood.

[0082] For simplicity, we will use an alternative notation here that utilizes the effective chiral and achiral moieties of macroscopic sensitivity. The achiral moiety includes contributions from either the solvent or degraded achiral CdTe particles. In the following notation, the chiral moiety changes sign while the chiral moiety changes sign, but the achiral moiety does not (the CPL direction having an equivalent effect).

number

number

number

number

number

[0083] Third harmonic hypermi scattering optical activity-forward scattering at 1065 nm and 1125 nm. As described above, the output-dependent measurement results for third harmonic (TH) forward scattering are presented for illumination with 1095 nm light. Figures 6A-6D show similar measurement results for Λ-CdTe and Δ-CdTe at two other wavelengths, 1065 nm and 1125 nm. A schematic diagram of the experimental setup is shown in the inset of Figure 6A. In all measurements, the incident light was left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is given by the equation y = Ax 3 The function is fitted. Clear optical activity is observed at both wavelengths. The sign of the optical activity is opposite to the symmetry of the CdTe nanohelix.

[0084] Figures 7A–7B show the multiphoton emission for illumination at 1065 nm. More specifically, Figures 7A–7B show the emission spectrum of a Λ-CdTe nanohelix suspension when illuminated with light at 1065 nm. The incident light is left-circularly polarized (LCP), linearly polarized, or right-circularly polarized (RCP). The incident power was 18.5 mW. For both forward and right-angle scattering, the signal detected at the TH wavelength stands out clearly against the multiphoton luminescence background.

[0085] Figures 8A–8I show comparative third-harmonic hypermi scattering for achiral CdTe nanoribbons. Achiral CdTe nanoribbons with the geometric shapes shown in Figures 8A–8C were measured using the same setup as that used for CdTe nanohelices. The TH intensity in the forward scattering geometric shape, detected simultaneously with illumination at 1095 nm light, is shown in Figures 8D and 8E. The data in the two plots are from two separate measurements performed under the same conditions. Presumably, due to the large variability in nanoribbon size, these results are noisier compared to nanohelices. Optical activity is not observed, as evidenced both by the fit and the calculated TH ellipticity in Figure 8F. Figures 8G and 8H show two separate measurements of TH intensity in right-angle scattering. In the first measurement, the fit shows a larger signal for incident LCP light. On the other hand, in the second measurement, the fit shows a larger signal for incident RCP light. Therefore, there is no consistent indication of optical activity. In fact, once the TH ellipticity is calculated (Figure 8I), the ellipticity is scattered around zero.

[0086] Figures 9A and 9B show the third harmonic super-Mie scattering optical activity in right-angle scattering, demonstrating the THMS optical activity. In Figure 9A, the TH intensity is shown perpendicular to the clockwise CdTe nanohelix (Δ-CdTe) as a function of the incident laser output at a wavelength of 1095 nm (λ) relative to LCP and RCP light. In Figure 9B, the multiphoton right-angle emission from the Λ-CdTe nanohelix is ​​shown simultaneously with the 1095 nm illumination. The TH signal (at 365 nm) clearly dominates the near-emission wavelength of the incident linearly polarized LCP and RCP light.

[0087] The third harmonic super-Mie scattering optical activity at 1065 nm and 1125 nm for right-angle scattering experiments at 1065 nm and 1125 nm is shown in Figures 10A-10D. TH intensity was measured at 1065 nm as a function of incident power. Figure 10A shows a Λ-CdTe nanohelix in a right-angle scattering setup, and Figure 10B shows a Δ-CdTe nanohelix in a right-angle scattering setup. The experimental setup is shown in the inset of Figure 10A. Similar measurement results at 1125 nm are presented in Figure 10C for Λ-CdTe and in Figure 10D for Δ-CdTe. In all measurements, the incident light was either left-circularly polarized (LCP) or right-circularly polarized (RCP). Each data point is the median of 50 measurements. The dataset is given by the equation y = Ax 3 Fit the function to the desired result.

[0088] The detected TH intensity is significantly lower in the forward scattering geometry, which is consistent with the results presented for illumination at 1095 nm discussed above. Furthermore, optical activity is observed, and its sign is affected by the symmetry of the CdTe nanohelix. However, for each sample, the sign of the optical activity is opposite to the sign in forward scattering.

[0089] Third harmonic Mie scattering polarization is shown in Figures 11A and 11B. In Figure 11A, the TH intensity in the forward direction is shown as a function of the rotation angle of the quarter-wavelength plate (AWP) relative to Δ-CdTe. LCP and RCP incident light produce LCP and RCP TH light, respectively. In Figure 11B, the TH intensity in the 90° direction is shown as a function of the AWP rotation angle relative to Δ-CdTe. LCP and RCP incident light produce linearly polarized TH light. All measurements were performed on incident 1095 nm light.

[0090] Figure 12 shows the multipolar spectral resolution of the nanohelix scattering cross section. The curves correspond to illumination by right- and left-circularly polarized light (LCP and RCP, respectively), as well as the electric dipole (ED), magnetic dipole (MD), electric quadrupole (EQ), magnetic quadrupole (QD), and total scattering cross section. The circular difference (CD) corresponds to the difference (Δ) in the scattering cross section.

[0091] To determine the contribution of the solvent to the third harmonic scattering (TH) signal, experiments were performed using a liquid medium containing 0.2% sodium dodecyl sulfate (SDS) in an aqueous medium (water) with forward and 90° emission. Figure 13A shows the TH intensity measured as a function of laser power for left circularly polarized (LCP) and right circularly polarized (RCP) incident light. A schematic diagram of the experimental setup is provided in the inset in Figure 13A. Clearly, there is no forward TH emission from the solvent. Figure 13B shows the TH intensity as a function of incident laser power for 0.2% SDS illuminated by LCP and RCP light. Clearly, there is no TH scattering from the solvent. The inset in Figure 13B shows a schematic diagram of the setup for measuring TH emission at right angles. In both plots, the sample was illuminated with 1095 nm light.

[0092] The line represents the linear fitting to y = Ax + B. For LCP, the coefficients A and B are 10, respectively. -3 and 3 × 10 -2 For RCP, these coefficients are -6.1 × 10⁻⁶, respectively. -3 and 5.6 × 10 -2 Therefore, we can conclude that the contribution of the solvent to the result can be ignored. Figure 13B shows the TH intensity radiated perpendicularly from SDS. The figure is constructed similarly to Figure 10A. For LCP, coefficients A and B are -1.1 × 10⁻⁶. -2 and 4.4 × 10 -2 For RCP, these coefficients are 2.4 × 10⁻⁶, respectively. -3 and -5.8 × 10 -2Therefore, the contribution of the solvent to the results can be ignored. These results unambiguously demonstrate that the TH results are due to the nonlinear optical properties of the CdTe nanohelix.

[0093] Third harmonic scattering / generation - Determination of 10 mm cuvette interface. All samples are measured in a quartz glass cuvette. Symmetrical fracture at the interface can lead to strong nonlinearity. Therefore, it is determined whether TH generation at air / quartz, quartz / solvent, solvent / quartz, and quartz / air interfaces contributes to the measured TH intensity.

[0094] The TH intensities measured in a forward scattering setting for various positions of the focus lens are shown in Figures 14A-14B. For incident linearly polarized light, four peaks in the TH intensity are observed. These peaks correspond to the four interfaces of the cuvette. When the focus lens is positioned between approximately 86 mm and 92 mm, the peaks are narrow, indicating no contribution from the interface. For incident LCP light, the TH intensity generated at the cuvette interface is much lower than that for linearly polarized light. In the CdTe nanohelix measurements, the incident light is circularly polarized, and the focus lens is positioned at 89.5 mm, clearly far from any interface. Therefore, in all of the measurement results, there is no contribution from TH generation at the glass interface. To support this observation, power-dependent measurement results using an empty cuvette are shown in Figure 14B. The filled circles and triangles correspond to LCP and RCP illumination, respectively. The lines are fitted to the equation y = Ax + B. For LCP, coefficients A and B are -4.1 × 10⁻⁶, respectively. -4 and 3.3 × 10 -3 For RCP, the coefficients A and B are 1.1 × 10⁻⁶, respectively. -3 and -2.3 × 10 -2 Therefore, the contribution from the glass interface can be ignored.

[0095] Furthermore, the results in Figure 14B are significant because they demonstrate that there is no TH generation from any of the optical components in the setup, regardless of the illumination output. Moreover, these same results indicate that the detector is unaffected by any external light sources, such as instrument LEDs and displays in the laboratory.

[0096] Next, tests are conducted for the presence of optical rotation. Figure 15A shows a schematic diagram of the setup. The fundamental wave is linearly polarized along the vertical (S) direction. The quarter-wavelength plate is not removed to avoid significantly altering the setup, however, its velocity axis is set parallel to the direction of the incident polarization. The polarizer (analyzer) to be analyzed is placed on a rotating stage in front of the detector. The 90° angular position corresponds to the vertical direction of polarization. The third harmonic signal is then measured as a function of the analyzer angle. For both chiral forms of the sample, the data are shown in Figure 15B. As can be seen, the third harmonic light is vertically polarized and there is no optical rotation that can be measured.

[0097] Third harmonic scattering / generation at the 1 mm cuvette interface is determined in Figure 16. More specifically, Figure 16 shows the TH intensity as a function of the position of the focus lens for illumination with linear and left circularly polarized (LCP) 1095 nm light (incident power = 15 mW). Measurements were performed using the forward scattering geometry. No third harmonic (TH) light was observed from the 1 mm cuvette interface.

[0098] Figures 17A–17D show the optical activity of third-harmonic supermie scattering at 1065 nm and 1125 nm when the sample was measured in a cuvette containing a 1 mm path length. Measurements of TH intensity as a function of output for Λ-CdTe and Δ-CdTe nanohelices placed in a cuvette containing a 1 mm path length are presented in Figures 17A–17D. The ellipticity in Figure 5A was calculated using these output-dependent curves.

[0099] Figures 5A–5E illustrate examples of THMS applications for characterizing ultra-small volume chiral nanostructures. Figure 5A shows proof-of-principle data demonstrating that a method according to a particular aspect of the present disclosure can clearly distinguish between Λ-CdTe and Δ-CdTe within a 1 mm thick optical cuvette (as opposed to a standard 1 cm cell). The THMS ellipticity was calculated from power-dependent curves measured at three different wavelengths. Figure 5B shows that within the same 1 mm cuvette, the TH intensity follows a clear third-order dependence as a function of laser power at a wavelength of 1095 nm. Despite the small cuvette dimensions, the kill optical effects for LCP and RCP, respectively, are clearly inversely sign due to the symmetry of the samples, indicating potential for application in very small volumes. Figure 5C shows a schematic diagram illustrating an example of the application of a technique according to a particular aspect of the present disclosure as an analytical tool for parallel combinatorial chemical synthesis. Figure 5D shows that high-throughput applications may be possible by scanning a laser beam within an optical objective lens to investigate the reaction conditions in detail. The reaction conditions involve generating a nanomolar amount of the desired compound in a minute volume (e.g., <1 μL) arranged across the entire microplate. The red arrow indicates the direction of the incident light. Figure 5E shows a schematic diagram of in-line reaction monitoring within the microreactor.

[0100] Therefore, these examples demonstrate the fundamental capability of nonlinear kill optical activity for Mie scattering represented by THMS. As determined above, contributions from THG, multiphoton luminescence, and supercontinuum generation were carefully excluded, and this effect was observed for semiconductor CdTe nanohelices at three different wavelengths. The scale of THMS is large, approximately 4.56 × 10⁻⁶ -14 m 3 V focusA TH elliptic of approximately 3° is observed from an illumination volume of similar size. According to the physical properties of Mie scattering, the effect is highly directional, with approximately 10 times more TH light detected in the forward direction compared to the lateral direction. The forward TH emission is circularly polarized, while the perpendicular TH emission is linearly polarized (vertically). In both cases, a distinct sign-reversed Kill optical response is observed. The sign reversal indicates that the forward and perpendicular emission is due to different sets of TH-effective sensitivity tensor components, thereby causing the phase between the chiral and achiral parts to change sign depending on the direction of emission. These results suggest a potential 10 -17 m 3 This opens the way for the kill optical characterization of semiconductor and other chiral nonmetallic particles of orders of magnitude in volume. The ability to evaluate such miniaturized reaction volumes provides a technical link between chemosynthesis and the exploration of data science requirements for chiral nanostructures. Furthermore, this capability can potentially be extended to chiral nanostructured particles such as extracellular vesicles, which have multiscale tissue and similar dimensions and are widely investigated today for cancer detection. By labeling with inorganic nanoparticles, high THMS intensity provides a pathway for detecting and counting the presence of rare extracellular vesicles, including microfluidic ones.

[0101] Therefore, this disclosure intends to describe the use of kill optical spectroscopy, which provides new optical dimensions and data sets that offer information for the structural analysis of nanostructured particles. Kill optical spectroscopy can be used for the robotic optimization of nanophotonic materials, but these spectroscopic methods typically require sample volumes that are incompatible with generating large chemical libraries. These novel optical tools can evaluate chirality features in ultrasmall volumes, such as 1 μL droplets, which are necessary for high-throughput synthesis and analytical stations for chiral compounds. A novel photonic effect that enables such capabilities—third harmonic Mie scattering optical activity—has been experimentally shown to be observed in suspensions of CdTe nanostructured helices in volumes several orders of magnitude smaller than 1 μL. Kill optical third harmonic emission was recorded when the CdTe helices were illuminated with laser beams of 1065 nm, 1095 nm, and 1125 nm, and the THMS intensity was approximately 10 times higher in the forward direction than in the lateral direction. The third harmonic ellipticity was approximately 3°. This is thought to be due to the effect of interference between chiral and achiral effective nonlinear sensitive tensor components. Therefore, the THMS for semiconductor helices is 10 -5 It provides the capability for rapid, high-throughput kill optical feature evaluation of sample volumes as small as μL.

[0102] Prior descriptions of embodiments have been provided for illustrative and explanatory purposes. They are not intended to be exhaustive or limit the disclosure. Individual elements or features of a particular embodiment are, in general, not limited to that particular embodiment, but are interchangeable where applicable and can be used in selected embodiments, even if not specifically shown or described. Furthermore, the same may vary in many ways. Such variations should not be considered deviations from this disclosure, and all such modifications are intended to be within the scope of this disclosure.

Claims

1. A method for detecting chiral properties from a sample, wherein the method is The steps include directing light towards the sample in contact with the chiral nanoparticles, A method comprising the step of detecting third harmonic Mie scattering (THMS) optical activity generated by the chiral nanoparticles in contact with the sample.

2. The method according to claim 1, wherein the third harmonic Mie scattering (THMS) optical activity is circularly polarized third harmonic (TH) radiation in the forward direction.

3. The method according to claim 1, wherein the sample has a volume of about 1 microliter or less.

4. The aforementioned sample is approximately 10 －５ The method according to claim 1, having a volume of microliters or more and about 1 microliter or less.

5. The method according to claim 1, wherein the chiral nanoparticles comprise a semiconductor material.

6. The method according to claim 1, wherein the chiral nanoparticles comprise cadmium telluride (CdTe).

7. The method according to claim 1, comprising a plurality of chiral nanoparticles that are self-assembled together such that the chiral nanoparticles define at least one self-assembled nanostructured helix.

8. The method according to claim 1, wherein the chiral nanoparticles comprise a plurality of chiral nanoparticles integrated together, and each chiral nanoparticle is in the form of a nanohelix having a length of about 5 micrometers or more and about 8 micrometers or less and a thickness of about 10 nm or more and about 50 nm or less.

9. The method according to claim 1, wherein the light is circularly polarized light.

10. An apparatus for detecting the chiral properties of a sample, wherein the apparatus is Chiral nanoparticles capable of generating third-harmonic Mie scattering (THMS) optical activity, and at least one microwell having a volume of about 1 microliter or less configured to hold the sample to be analyzed, A light source configured to generate light and direct the light towards the at least one microwell containing the chiral nanoparticles and the sample, An apparatus comprising: at least one detector configured to detect third harmonic Mie scattering (THMS) generated by the chiral nanoparticles in the at least one microwell.

11. The apparatus according to claim 10, wherein the chiral nanoparticles are provided in the sample within the microwell.

12. The apparatus according to claim 10, wherein the chiral nanoparticles are associated with the surface of the microwells.

13. The aforementioned microwells are approximately 10 －５ The apparatus according to claim 10, having a volume of more than a microliter and less than or equal to about 1 microliter.

14. The apparatus according to claim 10, wherein the chiral nanoparticles comprise a semiconductor material.

15. The apparatus according to claim 10, wherein the chiral nanoparticles comprise cadmium telluride (CdTe).

16. The apparatus according to claim 10, comprising a plurality of chiral nanoparticles that are self-assembled together such that the chiral nanoparticles define at least one self-assembled nanostructured helix.

17. The apparatus according to claim 10, wherein the chiral nanoparticles comprise a plurality of chiral nanoparticles integrated together, and each chiral nanoparticle is in the form of a nanohelix having a length of about 5 micrometers or more and about 8 micrometers or less and a thickness of about 10 nm or more and about 50 nm or less.

18. The apparatus according to claim 10, wherein the light source is configured to generate circularly polarized light and to guide the circularly polarized light.

19. The apparatus according to claim 10, wherein the at least one microwell comprises an array of microwells.

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