Surface enhanced Raman scattering substrate and preparation method and chiral recognition method thereof

Abstract

The invention relates to the technical field of chiral recognition, in particular to a surface-enhanced Raman scattering substrate, a preparation method thereof and a chiral recognition method. The surface-enhanced Raman scattering substrate comprises a substrate and a chiral molecular intercalation superlattice material layer arranged on the surface of the substrate, and the chiral molecular intercalation superlattice material layer comprises layered transition metal sulfide and chiral molecules embedded between the transition metal sulfide layers. According to the method, the chiral enantiomer is identified by utilizing the surface enhanced Raman scattering of the chiral transition metal sulfide, and direct and label-free identification and accurate quantitative analysis of the chiral enantiomer are realized by skillfully utilizing the internal chiral attribute of the chiral transition metal sulfide and the synergistic effect of the surface enhanced Raman scattering technology. The chiral recognition technology effectively overcomes the limitation of the existing chiral recognition technology in the aspects of sensitivity, universality, anti-interference capability, operation simplicity and the like, and remarkably improves the recognition efficiency and precision so as to adapt to diversified application scene requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of chiral recognition, and in particular to a surface enhanced Raman scattering substrate and a preparation method thereof and a chiral recognition method. Background Art

[0002] Chirality is a means of characterizing low-symmetry features of molecules, called enantiomers, which are mirror images of each other and cannot be superimposed. Although enantiomers are highly similar in physical and chemical properties, they have unique responses to some physiological processes such as biological activity, toxicity and pharmacological effects. Therefore, chiral recognition is crucial to ensure the effectiveness of drugs, accurate disease diagnosis and maintaining product quality.

[0003] Traditional chiral identification mainly relies on optical property measurement, such as circular dichroism (CD), which distinguishes enantiomers through the interaction between light and matter. However, these methods generally have problems such as low sensitivity, susceptibility to interference (such as ultraviolet absorption of salts and solvents), and insufficient precision, especially when dealing with weak chiral signals, weak absorption bands, and systems with small chiral differences.

[0004] Surface enhanced Raman scattering (SERS) technology is a highly sensitive, fast, accurate, and non-destructive molecular detection technology that can provide fingerprint spectra of different molecules and is expected to achieve direct, label-free chiral identification. However, existing SERS chiral identification methods mostly use indirect detection, which requires the use of secondary probes such as chiral selectors to interact stereospecifically with the analyte. This method can only reflect the changes in the probe signal and cannot capture the information of the analyte itself. Therefore, it is easily interfered by other substances, and the range of chiral enantiomers applicable to this method is very limited.

[0005] Chiral recognition by label-free SERS is a commonly used method to identify specific molecular information. This method can clearly distinguish the target enantiomers without the need for additional labeling. The key to achieving this goal is to construct a controllable chiral structure on the surface of the substrate material, thereby creating a unique chiral microenvironment that can induce the adsorption of enantiomers in a differential manner. However, in actual operation, there are difficulties in the preparation of asymmetric chiral nanostructures, which are currently mainly overcome by using specially designed surfaces (such as high Miller index surfaces of Cu / Ag) or complex synthetic strategies, such as the use of chiral templates and chiral imprinting. In addition, the lack of affinity between the analyte and the chiral recognition surface is also a problem to be solved, because the interaction between the two is weak. In order to solve this problem, it is often necessary to introduce additional binding mechanisms in experimental studies, such as the use of electrochemical potential regulation, but this limits the effective distinction of enantiomers and the generation of strong SERS signals.

[0006] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a surface enhanced Raman scattering substrate and a preparation method and a chiral recognition method thereof, aiming to solve the problems of the existing label-free SERS chiral recognition technology, namely, the difficulty in preparing asymmetric chiral nanostructures on the surface of the substrate material and the insufficient affinity between the analyte and the chiral recognition surface.

[0008] The technical solution of the present invention is as follows:

[0009] A first aspect of the present invention provides a surface enhanced Raman scattering substrate, wherein the surface enhanced Raman scattering substrate comprises a substrate and a chiral molecule intercalation superlattice material layer arranged on the surface of the substrate, and the chiral molecule intercalation superlattice material comprises layered transition metal sulfide and chiral molecules embedded between the transition metal sulfide layers.

[0010] Optionally, the thickness of the chiral molecule intercalation superlattice material layer is 20-50 nm.

[0011] Optionally, the transition metal sulfide is TaS2, and the chiral molecules are S-MBA and R-MBA.

[0012] Optionally, the substrate is composed of a silicon layer, a silicon dioxide layer and a metal layer stacked in sequence, and the metal layer is bonded to the chiral molecule intercalation superlattice material layer.

[0013] Optionally, the material of the metal layer is Au, Ag or Cu.

[0014] A second aspect of the present invention provides a method for preparing the surface enhanced Raman scattering substrate of the present invention, comprising the steps of:

[0015] providing a substrate;

[0016] A chiral molecule intercalation superlattice material layer is formed on the substrate to obtain the surface enhanced Raman scattering substrate.

[0017] Optionally, the step of forming a chiral molecular intercalation superlattice material layer on the substrate specifically includes:

[0018] Preparing a chiral molecule intercalation superlattice material solution;

[0019] A chiral molecule intercalation superlattice material solution is coated on the substrate, and annealing is performed to obtain the chiral molecule intercalation superlattice material layer.

[0020] Optionally, the chiral molecule intercalation superlattice material solution is prepared by dissolving the chiral molecule intercalation superlattice material in a solvent, and the solvent is at least one of water and isopropanol;

[0021] The annealing treatment is performed at a temperature of 50-70° C. and for a time of 10-14 hours.

[0022] The third aspect of the present invention provides a chirality recognition method, which comprises the steps of:

[0023] Providing the surface enhanced Raman scattering substrate of the present invention;

[0024] Adding a chiral enantiomer to be measured on the chiral molecule intercalation superlattice material layer of the surface enhanced Raman scattering substrate;

[0025] Raman scattering detection is performed to achieve the identification of chiral enantiomers.

[0026] Optionally, the chiral enantiomers are L-glucose and D-glucose, and the chiral enantiomers are L-histidine and D-histidine.

[0027] Beneficial effects: The present invention provides a surface enhanced Raman scattering substrate, the surface enhanced Raman scattering substrate comprises a substrate and a chiral molecule intercalation superlattice material layer arranged on the surface of the substrate, the chiral molecule intercalation superlattice material comprises a layered transition metal sulfide and a chiral molecule embedded between the transition metal sulfide layers, and the chiral molecule intercalation superlattice material is also referred to as a chiral transition metal sulfide. The present invention utilizes surface enhanced Raman scattering (SERS) of chiral transition metal sulfides such as tantalum disulfide (TaS2) to identify chiral enantiomers, and by cleverly utilizing the intrinsic chiral properties of chiral transition metal sulfides and the synergistic effect of SERS technology, direct, label-free identification and precise quantitative analysis of chiral enantiomers are achieved.

[0028] In addition, the present invention synthesizes chiral transition metal sulfides by wet chemical intercalation method, ensuring that the enantioselectivity remains stable between different batches and has excellent reproducibility, enhancing the reliability and repeatability of the chiral recognition method, and having wide applicability and versatility in identifying different types of chiral enantiomers. In addition, the present invention does not require additional bonding strategies, and can directly utilize the local asymmetric sites induced by chiral transition metal sulfides such as chiral tantalum disulfide between the atomic layer and the surface atomic defects to achieve stereospecific interaction with the analyte, thereby directly and label-free identification of different biological chiral enantiomers, and accurate quantitative analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the insertion of chiral molecule S- / R-MBA into pristine TaS2 to form chiral TaS2.

[0030] Figure 2 These are the characterization results of chiral TaS2; among them, (a) is XRD characterization, (b) is Raman spectrum characterization, (c) and (d) are circular dichroism spectrum characterization.

[0031] Figure 3 Schematic diagram of the SERS chiral identification principle; (a) is a schematic diagram of the two-dimensional chiral S- / R-TaS2 identifying chiral enantiomers, (b) is the SERS spectrum of D- / L-glucose on S- / R-TaS2, and (c) is the SERS spectrum of D-glucose on S-TaS2 at 10 -3 M to 10 -9 SERS spectra in the range of M concentration, (d) L-glucose on R-TaS2 at 10 -3 M to 10 -9 SERS spectra over the concentration range of M.

[0032] Figure 4 The SERS chiral identification curve of glucose simulation; (a) is the SERS spectrum of the enantiomeric excess (ee) ratio range (0-100%) of the mixture of D-glucose and L-glucose on S-TaS2, (b) is the SERS spectrum of the mixture of D-glucose and L-glucose on S-TaS2 using I at different molar values 660 The regression diagram of the actual value and measured value of the peak intensity of D-glucose, (c) is the peak intensity of D-glucose on S-TaS2 at 10 -3 M to 10 -9 (d) is the linear regression diagram of the measured value and the actual value of D-glucose at different concentrations, (e) is the SERS spectrum stability test of D-glucose on S-TaS2, and (f) is the SERS spectrum stability test of L-glucose on R-TaS2 substrate.

[0033] Figure 5 Schematic diagram of SERS chiral identification of histidine; (a) is the SERS spectrum of L-histidine and D-histidine on S- / R-TaS2, showing enantioselective reaction, (b) is the SERS spectrum of D-histidine on S-TaS2 chiral substrate at different concentrations (10 - 3 M to 10 -6 M) range, (c) SERS spectra of L-histidine on R-TaS2 chiral substrate at different concentrations (10 -3 M to 10 -6 (d) is the linear regression diagram of the measured value and the actual value of L-histidine in a certain concentration range. DETAILED DESCRIPTION

[0034] The present invention provides a surface enhanced Raman scattering substrate and a preparation method thereof and a chiral recognition method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] The existing chiral recognition methods have the following defects:

[0036] 1. Limitations of optical property measurement: Traditional chiral identification mainly relies on optical property measurement, such as circular dichroism (CD), to distinguish enantiomers through the interaction between light and matter. However, these methods generally have problems such as limited sensitivity, susceptibility to interference (such as ultraviolet absorption of salts and solvents), and insufficient precision, especially when dealing with weak chiral signals, weak absorption bands, and systems with small chiral differences.

[0037] 2. Indirect detection and probe dependence: Most current SERS chiral recognition technologies use indirect detection strategies, which require the use of secondary probes such as chiral selectors to interact stereospecifically with the analyte. However, this method can only reflect the change in the probe signal and fails to capture the information of the analyte itself. Therefore, it is easily interfered by other substances, and the range of chiral enantiomers applicable to this method is limited.

[0038] 3. Chiral recognition by label-free SERS: The key to this recognition method is to construct a controllable chiral structure on the surface of the substrate material, thereby creating a unique chiral microenvironment that can induce the adsorption of enantiomers in a differential manner. However, this recognition method has the difficulty of preparing asymmetric chiral nanostructures. Currently, it mainly relies on special surfaces (such as Cu / Ag high Miller index surfaces) or complex methods such as chiral templates and chiral imprinting to prepare asymmetric chiral nanostructures. In addition, there is also the problem of insufficient affinity between analytes and chiral surfaces. This is because the interaction between many analytes and chiral surfaces is weak and requires the use of additional bonding strategies (such as electrochemical potential), which limits the effective distinction of enantiomers and the generation of strong SERS signals.

[0039] Based on this, an embodiment of the present invention provides a surface enhanced Raman scattering substrate, wherein the surface enhanced Raman scattering substrate includes a substrate and a chiral molecule intercalation superlattice material layer arranged on the surface of the substrate, and the chiral molecule intercalation superlattice material includes layered transition metal sulfide and chiral molecules embedded between the transition metal sulfide layers.

[0040] Transition metal sulfides are two-dimensional layered materials. The unique gaps between the two-dimensional layered materials allow many foreign molecules to be inserted into them, while keeping the crystal structure within the atomic layer of the two-dimensional layered material intact, thus forming a perfect superlattice. Through the chemical intercalation method, chiral molecules can be successfully inserted into two-dimensional layered crystals to form chiral molecule intercalation superlattice materials.

[0041] The present invention uses surface enhanced Raman scattering (SERS) of chiral molecular intercalation superlattice materials (i.e., chiral transition metal sulfides) to identify chiral enantiomers, and achieves direct, label-free identification and precise quantitative analysis of chiral enantiomers by cleverly utilizing the intrinsic chiral properties of chiral transition metal sulfides and the synergistic effect of SERS technology. This is mainly because the local asymmetric sites induced between the atomic layers and surface atomic defects of chiral transition metal sulfides achieve stereospecific interactions with the analyte, thereby achieving chiral enantiomer recognition.

[0042] Specifically, the SERS of the present invention using chiral transition metal sulfides to identify chiral enantiomers has the following technical advantages:

[0043] 1. Different chiral enantiomers can be directly distinguished without labeling, which increases the scope of application of chiral enantiomers. This can reduce the investment cost and operating cost of molecular recognition technology and improve the economy and popularity of molecular recognition technology.

[0044] 2. The chiral enantiomeric specificity inherent in the chiral transition metal sulfide nanostructures used is achieved through an optimized single-step wet chemical synthesis process without any additional post-processing or modification. The production process itself is simple, with the advantages of low cost and easy manufacturing. The chiral tantalum disulfide is synthesized by wet chemical intercalation, which ensures that its enantioselectivity remains stable between different batches and has excellent reproducibility, enhancing the reliability and repeatability of the chiral enantiomer recognition method.

[0045] 3. It allows identification of the spectral information of the target chiral enantiomer while eliminating the interference of complex biological matrices, thereby directly and label-free identification of different biological chiral enantiomers and precise quantitative analysis, thus improving the accuracy of identification.

[0046] 4. L- / D-glucose and L- / D-histidine were selected as chiral pair models, and SERS studies were used to reveal the obvious enantiomeric-specific interactions between chiral enantiomers and chiral TaS2, forming unique SERS peak patterns and peak intensity ratio changes, realizing the identification of chiral enantiomers, and demonstrating the wide applicability and versatility of this method in identifying different types of chiral enantiomers.

[0047] 5. No additional bonding strategies are required. The local asymmetric sites induced by chiral transition metal sulfides such as chiral tantalum disulfide between the atomic layer and the surface atomic defects can be directly utilized to achieve stereospecific interaction with the analyte, thereby directly and label-free identifying different biological chiral enantiomers and performing precise quantitative analysis.

[0048] In one embodiment, the transition metal sulfide is TaS2, and the chiral molecules are S-MBA and R-MBA.

[0049] Through the chemical intercalation method, the chiral molecules R-α-methylbenzylamine (R-MBA, C6H5CH(CH3)NH2) and S-α-methylbenzylamine (S-MBA,

[0050] C6H5CH(CH3)NH2) is inserted into the two-dimensional layered crystal TaS2 to form a chiral molecular intercalation superlattice material as a substrate for surface-enhanced Raman scattering.

[0051] The embodiments of the present invention achieve direct, label-free identification and precise quantitative analysis of chiral enantiomers such as L- / D-glucose and L- / D-histidine by cleverly utilizing the intrinsic chiral properties of TaS2 and the synergistic effect of SERS technology. The embodiments of the present invention effectively overcome the limitations of existing chiral recognition technologies in terms of sensitivity, universality, anti-interference ability, and ease of operation, and significantly improve recognition efficiency and accuracy to meet the needs of diversified application scenarios.

[0052] In one embodiment, the method for preparing the chiral TaS2 comprises the steps of:

[0053] 80-100 mg of H-TaS2 (i.e., original TaS2, also called intrinsic TaS2) powder is put into a container (such as a glass vial), and 3-4 mL of S-MBA or R-MBA is added to the container under an inert atmosphere (such as N2 atmosphere) to obtain a mixture, and the mixture is stirred at 60-70° C. under an inert atmosphere for 70-80 hours (this stirring step is for intercalation reaction);

[0054] After the above stirring (i.e., intercalation reaction) is completed, the system after the reaction is centrifuged at 10000-12000 rpm for 10-20 min, and then the chiral TaS2 to be purified is collected; the chiral TaS2 is then redispersed in isopropanol and centrifuged, and the dispersion / centrifugation is repeated three times, and the cycle is thoroughly washed; finally, the purified chiral TaS2 is obtained after vacuum drying at 60-80°C for 10-15 hours.

[0055] The embodiment of the present invention synthesizes chiral TaS2 by wet chemical intercalation method, and realizes direct, label-free identification and precise quantitative analysis of the enantiomers of L- / D-glucose and L- / D-histidine by cleverly utilizing the intrinsic chiral properties of TaS2 and the synergistic effect of SERS technology. The preparation method of chiral TaS2 has the advantages of simple preparation process, low cost and easy preparation. In addition, the chiral tantalum disulfide is synthesized by wet chemical intercalation method, which ensures that its enantioselectivity remains stable between different batches and has excellent reproducibility, thereby enhancing the reliability and repeatability of the chiral recognition method.

[0056] In one embodiment, the thickness of the chiral molecule intercalation superlattice material layer is 20-50 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0057] In one embodiment, the substrate is composed of a silicon layer, a silicon dioxide layer and a metal layer stacked in sequence, and the metal layer is bonded to the chiral molecular intercalation superlattice material layer.

[0058] In one embodiment, the material of the metal layer is Au, Ag or Cu.

[0059] An embodiment of the present invention provides a method for preparing the surface enhanced Raman scattering substrate as described above, which comprises the steps of:

[0060] providing a substrate;

[0061] A chiral molecule intercalation superlattice material layer is formed on the substrate to obtain the surface enhanced Raman scattering substrate.

[0062] In one embodiment, the step of forming a chiral molecular intercalation superlattice material layer on the substrate specifically includes:

[0063] Preparing a chiral molecule intercalation superlattice material solution;

[0064] A chiral molecule intercalation superlattice material solution is coated on the substrate, and annealing is performed to obtain the chiral molecule intercalation superlattice material layer.

[0065] In one embodiment, the chiral molecule intercalation superlattice material solution is prepared by dissolving the chiral molecule intercalation superlattice material in a solvent, and the solvent is at least one of water and isopropanol.

[0066] In one embodiment, the annealing treatment is performed at a temperature of 50-70° C. (eg, 60° C.) and a time of 10-14 h (eg, 12 h).

[0067] The embodiment of the present invention provides a chirality recognition method, which comprises the steps of:

[0068] Providing a surface enhanced Raman scattering substrate according to an embodiment of the present invention;

[0069] Adding a chiral enantiomer to be measured on the chiral molecule intercalation superlattice material layer of the surface enhanced Raman scattering substrate;

[0070] Raman scattering detection is performed to achieve the identification of chiral enantiomers.

[0071] In one embodiment, the chiral enantiomer is L- / D-glucose and the chiral enantiomer is L- / D-histidine.

[0072] The chirality recognition method provided by the embodiment of the present invention has the following technical advantages:

[0073] 1. Direct label-free identification and quantification: By combining chiral transition metal dichalcogenides (taking chiral TaS2 as an example) with SERS technology, the local asymmetric sites induced by chiral TaS2 between the atomic layer and the surface atomic defects are utilized to achieve stereospecific interaction with the analyte (i.e. the chiral enantiomer to be measured), thereby directly and label-free identifying different biological chiral enantiomers and performing precise quantitative analysis.

[0074] 2. Stable preparation and reproducibility of chiral TaS2: Chiral tantalum disulfide is synthesized by wet chemical intercalation, which ensures that its enantioselectivity remains stable between different batches and has excellent reproducibility, enhancing the reliability and repeatability of the chiral recognition method.

[0075] 3. Verification and application examples of model chiral pairs: L-glucose and D-glucose were selected as chiral pair models. SERS studies revealed obvious enantiospecific interactions between the two and chiral TaS2, forming unique SERS peak patterns and peak intensity ratio changes. This method was successfully applied to the chiral identification of L-glucose and D-glucose in saliva samples, fully verifying its practical value in the biomedical field.

[0076] 4. Demonstration of the universality and versatility of the method: Further by detecting the enantiospecific recognition of L-histidine and D-histidine with the other chirality, the broad applicability and versatility of this method in identifying different types of chiral molecules were demonstrated.

[0077] The present invention is described in detail below through specific embodiments.

[0078] 1. Preparation of S- / R-TaS2 chiral molecular intercalation superlattice materials

[0079] Preparation process of S-TaS2 chiral molecular intercalation superlattice material: Take 100mg H-TaS2 (original TaS2) powder and put it into a glass vial. Under the protection of N2, add 4mL S-MBA to the vial to obtain a mixture; stir the mixture for 72 hours under N2 atmosphere at 65°C. After the stirring is completed, the post-reaction system is centrifuged at 11000rpm for 10min, and then the chiral molecular intercalation superlattice material to be purified is collected. Subsequently, the chiral molecular intercalation superlattice material to be purified is redispersed in isopropanol, and the dispersion / centrifugation is repeated three times, and the cycle is thoroughly washed. Finally, the purified chiral molecular intercalation superlattice material is obtained after vacuum drying at 60°C for 12 hours.

[0080] The preparation process of R-TaS2 chiral molecular intercalation superlattice material is basically the same as the preparation process of the above-mentioned S-TaS2 chiral molecular intercalation superlattice material, with the only difference being that the added S-MBA is replaced by R-MBA.

[0081] like Figure 1 As shown in the figure, S-MBA and R-MBA chiral molecules are successfully embedded into the van der Waals spacing of layered original TaS2, thereby forming a chiral molecular intercalation superlattice material (i.e., chiral TaS2). Using X-ray diffraction analysis (XRD), it is found that compared with H-TaS2, the chiral S- / R-TaS2 diffraction peak plane obviously moves toward the low diffraction angle direction. The XRD results show that there is no difference between S-TaS2 and R-TaS2 chiral materials, indicating that the intercalation of different chiral enantiomers does not affect the structure of the chiral superlattice, see Figure 2 (a). Raman spectroscopy further confirmed that the chiral S- / R-TaS2 material retains the inherent lattice structure of the intrinsic H-TaS2 crystal, see Figure 2 (b). Intrinsic H-TaS2 crystals usually have a wavelength of about 284 cm -1 The performance is E 1 2 g In-plane phonon mode, at about 402 cm -1 A 1 g These properties are well preserved in S- / R-TaS2 chiral materials, although the intensity is increased. 1 g Small mode shifts up to 400 cm -1 . A 1 gThis blue shift of the mode indicates a strengthening of the in-plane vibrational modes upon insertion and is attributed to the suppression of long-range Coulomb interlayer interactions. These observations suggest the absence of any identifiable phase transition upon intercalation. Furthermore, there are no significant differences between the S-TaS2 and R-TaS2 chiral superlattices, indicating that they have similar structures. The chirality induction of the S- / R-TaS2 superlattices was finally confirmed by circular dichroism (CD) studies. While the intrinsic H-TaS2 exhibits minimal CD response, the corresponding S- / R-TaS2 chiral superlattice clearly displays opposite CD absorption properties in the wavelength range of 250-280nm. This highlights the significant preference for the absorption of light of different circular polarizations, thus validating the successful incorporation of the selected chiral molecule into the host layer. The CD spectral peak positions of the chiral superlattices remain unchanged compared to the pure chiral molecules, see Figure 2 This observation indicates that the intrinsic molecular structure and chiral optical properties are largely unaffected, which may be attributed to the non-covalent van der Waals interaction between the host and the chiral molecular intercalant. In addition, in-depth analysis by high-resolution scanning tunneling electron microscopy (STEM) revealed that the interlayer spacing was changed from the original Increase to (See Figure 1 ), and the planes of S- / R-TaS2 have essentially the same features as the planes of intrinsic H-TaS2. This demonstrates that the H-TaS2 host layer can maintain its original crystal structure even after insertion, which is essential for retaining and integrating its intrinsic electronic properties and molecular chirality. Nitrogen adsorption-desorption studies found that a large amount of interlayer expansion increases the surface area of ​​the S- / R-TaS2 chiral superlattice. The enhanced specific surface area not only supports interlayer expansion, but also facilitates an increase in the number of active sites. There will be additional space within the layer for the analyte to contact the chiral substrate, which is particularly important in chiral recognition.

[0082] 2. Chiral recognition of L- / D-glucose based on SERS

[0083] 1) Preparation of a surface-enhanced Raman scattering substrate with S-TaS2 as the substrate: The S-TaS2 aqueous solution prepared in step 1 is spin-coated on a substrate composed of a silicon layer, a silicon dioxide layer and an Au layer stacked in sequence (denoted as Si / SiO2 / Au), and annealed at 60°C for 12 hours to obtain a S-TaS2 layer on the substrate, thereby obtaining a surface-enhanced Raman scattering substrate with S-TaS2 as the substrate, see Figure 3 As shown in (a).

[0084] 2) Preparation of a surface enhanced Raman scattering substrate with R-TaS2 as the substrate: The R-TaS2 aqueous solution prepared in step 1 is spin-coated on a substrate composed of a silicon layer, a silicon dioxide layer and an Au layer stacked in sequence (denoted as Si / SiO2 / Au), and annealed at 60°C for 12 hours to obtain an R-TaS2 layer on the substrate, thereby obtaining a surface enhanced Raman scattering substrate with R-TaS2 as the substrate, see Figure 3 As shown in (a).

[0085] 3) Non-chiral pristine H-TaS2 and gold substrate

[0086] Figure 3 (a) shows a schematic diagram of the principle of using SERS to identify chiral enantiomers on S- / R-TaS2 chiral superlattice. L- / D-glucose was selected as a typical chiral enantiomer. The chiral enantiomer selective recognition test of L- / D-glucose was first carried out on the achiral original H-TaS2 (formed on Si / SiO2 / Au) substrate. The results showed that regardless of the presence of L- / D-glucose, no detectable peaks were observed in the SERS spectrum of the H-TaS2 substrate at high analyte concentrations, indicating that the achiral H-TaS2 substrate is not suitable for carrying chiral molecules. Subsequently, it was tested on the S- / R-TaS2 chiral superlattice. When L- / D-glucose came into contact with the S- / R-TaS2 chiral superlattice substrate, it showed enantiomeric specific adsorption and a clearly distinguishable SERS molecular spectrum appeared, see Figure 3 (b). The SERS spectra of each sample were repeated 5 times, and the relative standard deviation of R-TaS2 was calculated to be about 2.3-2.5%, and the relative standard deviation of S-TaS2 was about 2-2.4%. These results show that the present invention has a high level of spectral reproducibility. For quantitative analysis, the chiral S-TaS2 substrate was quenched from 4×10 -9 -4×10 -3 SERS measurements were performed on D-glucose at different concentrations. S-TaS2 showed an enantioselective reaction to D-glucose at 650-670 cm -1 and 860-880cm -1 There is an obvious SERS peak between Figure 3 The detection limit (LOD) was then calculated, and the strongest SERS peak (650-670cm -1 ) intensity was fitted to the logarithmic concentration of D-glucose. A positive linear correlation was observed with increasing concentration, and a high R of 0.985-0.990 was shown. 2The chiral R-TaS2 substrate was also studied under the same conditions and the results showed a similar but opposite trend. The SERS signal was highly responsive to changes in L-glucose concentration. By fitting the 650-670cm -1 The peak intensity was linearly correlated with the logarithmic concentration of L-glucose. 2 The value was determined to be 0.989-0.992, and the LOD was calculated to be approximately 0.80-0.82 nM, see Figure 3 (d) The remarkable SERS performance can be attributed to the synergistic effect of multiple factors, including the high asymmetry of the chiral substrate, the tightly interconnected chiral network structure, the extended superlattice, and the resulting increase in surface roughness.

[0087] The enantioselectivity originates from the stereospecific interactions between glucose and the chiral structure of S- / R-TaS2. These interactions cause glucose enantiomers to adsorb on S- / R-TaS2 with different geometries and different degrees of interaction affinity. The anisotropic surface defects and chirality found on the chiral surface of S- / R-TaS2 create an inherent asymmetric molecular environment, which is a key factor in inducing stereospecific interactions between the analyte and the chiral surface.

[0088] In order to demonstrate the practical feasibility of the invention, the present invention performs multiple measurements on two enantiomers in a glucose mixture consisting of L-glucose and D-glucose, and accurately estimates their relative compositions.

[0089] Specifically, the ee% in the glucose mixture was determined using the following formula:

[0090] Among them C DG and C LG are the relative concentrations of D-glucose and L-glucose, respectively. First, the SERS spectra of S-TaS2 substrate in glucose mixtures with D-glucose concentrations ranging from 0% to 100% were recorded. Figure 4 (a) shows that as the concentration of D-glucose in the glucose mixture increases, the SERS intensity also increases. Next, a calibration curve was developed using I in glucose mixtures from 0 to 100% at different ee% ratios. 660 The corresponding calibration curve shows a high degree of linearity, R 2 This is also confirmed by the value of about 0.995, see Figure 4(c). This demonstrates good prediction accuracy and the feasibility of identifying accurate enantiomeric excess values. To verify the reliability of the measurements, composition predictions for two binary mixtures were performed, consisting of 25% and 50% D-glucose, respectively. The measured values ​​correlated strongly with the known concentration values, showing only an absolute difference of approximately 0.8-1.0%, see Figure 4 (b) and (d). Next, the stability of S- / R-TaS2 chiral substrate for glucose sensing was studied. Figure 4 (e) and (f) show SERS spectra recorded in air environment for 0-60 days. After 2 months, the SERS peak intensity shows limited degradation, indicating that the stability of S- / R-TaS2 chiral substrate is quite good.

[0091] 3. Chiral recognition of L- / D-histidine based on SERS

[0092] Amino acid profiling has been effectively used for early detection of cancer. In particular, L-histidine is ubiquitous in nature and is a widely recognized biomarker for early detection of various types of cancer. The versatility of the technique was verified by studying the SERS chiral discrimination of another chiral pair, L- and D-histidine. The SERS detection of L- and D-histidine enantiomers was performed on S- / R-TaS2 chiral substrates. The SERS spectra showed enantiospecific molecular patterns unique to L- and D-histidine. Figure 5 As shown in (a), D-histidine exhibits preferential adsorption and binding to the S-TaS2 chiral substrate and exhibits an obvious SERS response. By performing regression analysis on the SERS spectra of D-histidine at different concentrations, D-histidine can be quantitatively analyzed with a linear accuracy of 0.958-0.962 and a LOD of 2.2-2.4 μM. Figure 5 As shown in (b). L-histidine showed enantioselectivity for the R-TaS2 chiral substrate and exhibited a significant SERS response. SERS analysis can quantify L-histidine, with a linear accuracy of 0.968-0.972 based on regression analysis and a LOD of 0.88-0.92 μM, as shown in Figure 5 By establishing a calibration curve close to ideal linearity between the measured value and the actual value of L-histidine, the composition measurement results of the two samples of 20μM and 1mM L-histidine are in good agreement with the actual values, as shown in (c). Figure 5 As shown in (d).

[0093] In summary, the present invention provides a surface enhanced Raman scattering substrate and a preparation method thereof and a chiral recognition method. The present invention combines chiral transition metal disulfides with SERS technology, and utilizes the local asymmetric sites induced by chiral transition metal disulfides between the atomic layer and the surface atomic defects to achieve stereospecific interaction with the analyte, thereby directly and label-freely identifying different biological enantiomers and performing precise quantitative analysis. The chiral recognition technology of the present invention effectively overcomes the limitations of existing chiral recognition technologies in terms of sensitivity, universality, anti-interference ability, and ease of operation, and significantly improves recognition efficiency and accuracy. Specifically, it has the following characteristics: (1) It has extremely high detection sensitivity and can detect chiral molecule concentrations at the nanomolar level. For example, the detection limits for D- and L-glucose are approximately 0.88-0.90 nM and 0.80-0.82 nM, respectively. (2) It has excellent reproducibility and stability. The chiral TaS2 prepared by optimizing the single-step wet chemical intercalation method has excellent reproducibility between different batches, which ensures the reliability and repeatability of the method. (3) The relative standard deviation of multiple repeated SERS spectra is low (approximately 2.3%-2.4%), which verifies the high spectral reproducibility of the experiment. (4) It has broad application prospects and is suitable for analytical chemistry, nanoscience, biomedical diagnosis, environmental monitoring, food safety, pharmaceutical industry and other fields. It provides an efficient and accurate tool for the identification and analysis of chiral molecules, and is expected to promote scientific research, technological innovation and industrial development in related fields.

[0094] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A surface enhanced Raman scattering substrate, characterized in that: The surface enhanced Raman scattering substrate comprises a substrate and a chiral molecule intercalation superlattice material layer arranged on the surface of the substrate, and the chiral molecule intercalation superlattice material comprises layered transition metal sulfide and chiral molecules embedded between the transition metal sulfide layers.

2. The surface enhanced Raman scattering substrate according to claim 1, characterized in that: The thickness of the chiral molecule intercalation superlattice material layer is 20-50 nm.

3. The surface enhanced Raman scattering substrate according to claim 1, characterized in that: The transition metal sulfide is TaS2, and the chiral molecules are S-MBA and R-MBA.

4. The surface enhanced Raman scattering substrate according to claim 1, characterized in that: The substrate is composed of a silicon layer, a silicon dioxide layer and a metal layer which are stacked in sequence, and the metal layer is bonded to the chiral molecule intercalation superlattice material layer.

5. The surface enhanced Raman scattering substrate according to claim 4, characterized in that: The material of the metal layer is Au, Ag or Cu.

6. A method for preparing a surface enhanced Raman scattering substrate according to any one of claims 1 to 5, characterized in that: Includes steps: providing a substrate; A chiral molecule intercalation superlattice material layer is formed on the substrate to obtain the surface enhanced Raman scattering substrate.

7. The method for preparing a surface enhanced Raman scattering substrate according to claim 6, characterized in that: The step of forming a chiral molecular intercalation superlattice material layer on the substrate specifically comprises: Preparing a chiral molecule intercalation superlattice material solution; A chiral molecule intercalation superlattice material solution is coated on the substrate, and annealing is performed to obtain the chiral molecule intercalation superlattice material layer.

8. The method for preparing a surface enhanced Raman scattering substrate according to claim 7, characterized in that: The chiral molecule intercalation superlattice material solution is prepared by dissolving the chiral molecule intercalation superlattice material in a solvent, wherein the solvent is at least one of water and isopropanol; The annealing treatment is performed at a temperature of 50-70° C. and for a time of 10-14 hours.

9. A chirality recognition method, characterized in that: Includes steps: Providing a surface enhanced Raman scattering substrate according to any one of claims 1 to 5; Adding a chiral enantiomer to be measured on the chiral molecule intercalation superlattice material layer of the surface enhanced Raman scattering substrate; Raman scattering detection is performed to achieve the identification of chiral enantiomers.

10. The chirality recognition method according to claim 9, characterized in that: The chiral enantiomers are L-glucose and D-glucose, and the chiral enantiomers are L-histidine and D-histidine.

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