A surface-enhanced raman scattering substrate, a preparation method thereof and a chiral recognition method

Abstract

The present application relates to the technical field of chiral recognition, and particularly relates 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 molecule intercalated superlattice material layer arranged on the surface of the substrate. The chiral molecule intercalated superlattice material comprises layered transition metal sulfide and chiral molecules embedded between the layers of the transition metal sulfide. The present application utilizes the surface-enhanced Raman scattering of chiral transition metal sulfide to recognize chiral enantiomers. By skillfully utilizing the synergistic effect of the intrinsic chiral property of chiral transition metal sulfide and the surface-enhanced Raman scattering technology, direct, label-free recognition and accurate quantitative analysis of chiral enantiomers are realized. The chiral recognition technology of the present application effectively overcomes the limitations of existing chiral recognition technologies in terms of sensitivity, universality, anti-interference ability and operation simplicity, significantly improves the recognition efficiency and accuracy, and adapts to diversified application scene requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chiral recognition, and particularly relates to a surface-enhanced Raman scattering substrate, a preparation method thereof and a chiral recognition method. BACKGROUND

[0002] Chirality is a means of characterizing the low-symmetry feature of molecules, which are called enantiomers, and they present as mirror images that 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 for ensuring the effectiveness of drugs, accurate disease diagnosis and maintaining product quality.

[0003] Traditional chiral recognition mainly relies on optical property determination, such as circular dichroism (CD) distinguishing enantiomers through the interaction between light and matter. However, these methods generally have low sensitivity, are easily disturbed (such as UV absorption of salt and solvent), and have insufficient accuracy, especially when dealing with weak chiral signals, weak absorption bands and small chiral differences.

[0004] Surface-enhanced Raman scattering (SERS) technology is a sensitive, rapid, accurate and non-destructive molecular detection technology, which can provide the fingerprint spectrum of different molecules and is expected to realize direct and label-free chiral recognition. However, existing SERS chiral recognition methods mostly use indirect detection, which needs to use secondary probes such as chiral selectors to have stereospecific interaction with analytes. This method can only reflect the change of probe signal and cannot capture the information of analytes itself, so it is easily disturbed by other substances, and the range of chiral enantiomers suitable for this method is very limited.

[0005] Label-free SERS chiral recognition is a method commonly used to identify specific molecular information. This method can clearly distinguish target enantiomers without additional labeling. The key to achieving this goal is to construct a controllable chiral structure on the surface of the substrate material, and then create a unique chiral microenvironment that can induce enantiomers to adsorb in a differential manner. However, in actual operation, there are difficulties in the preparation of asymmetric chiral nanostructures, and at present, special designed surfaces (such as high Miller index surfaces of Cu / Ag) or complex synthesis strategies, such as using chiral templates and chiral imprinting, are mainly used to overcome this problem. 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 them is weak. In order to solve this problem, additional binding mechanisms are often introduced in experimental studies, such as using electrochemical potential regulation, but this limits the effective differentiation of enantiomers and the generation of strong SERS signals.

[0006] Therefore, the prior art remains to be improved and developed. SUMMARY

[0007] In view of the above deficiencies of the prior art, the purpose of the present application 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 non-labeled SERS chiral recognition technology, i.e., 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 solutions of the present application are as follows:

[0009] In a first aspect of the present application, a surface enhanced Raman scattering substrate is provided, wherein the surface enhanced Raman scattering substrate comprises a substrate and a chiral molecule intercalated superlattice material layer arranged on the surface of the substrate, and the chiral molecule intercalated superlattice material comprises layered transition metal sulfide and chiral molecules intercalated between the layers of transition metal sulfide.

[0010] Optionally, the thickness of the chiral molecule intercalated 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 arranged in sequence, and the metal layer is arranged in close contact with the chiral molecule intercalated superlattice material layer.

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

[0014] In a second aspect of the present application, a preparation method of the surface enhanced Raman scattering substrate is provided, comprising the following steps:

[0015] providing a substrate;

[0016] forming a chiral molecule intercalated superlattice material layer on the substrate to obtain the surface enhanced Raman scattering substrate.

[0017] Optionally, the step of forming a chiral molecule intercalated superlattice material layer on the substrate specifically comprises:

[0018] configuring a chiral molecule intercalated superlattice material solution;

[0019] coating the chiral molecule intercalated superlattice material solution on the substrate, and performing annealing treatment to obtain the chiral molecule intercalated superlattice material layer.

[0020] Optionally, the chiral molecule intercalated superlattice material solution is prepared by dissolving chiral molecule intercalated superlattice material in a solvent, and the solvent is at least one of water and isopropyl alcohol.

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

[0022] In a third aspect, the present application provides a chiral recognition method, comprising the steps of:

[0023] The surface enhanced Raman scattering substrate is provided.

[0024] A chiral enantiomer to be detected is added to the chiral molecule intercalated superlattice material layer of the surface enhanced Raman scattering substrate.

[0025] Raman scattering detection is performed to recognize the chiral enantiomer.

[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 application provides a surface enhanced Raman scattering substrate, which comprises a substrate and a chiral molecule intercalated superlattice material layer arranged on the surface of the substrate, and the chiral molecule intercalated superlattice material comprises layered transition metal sulfide and chiral molecules embedded between the transition metal sulfide layers, and the chiral molecule intercalated superlattice material is also referred to as chiral transition metal sulfide. The present application utilizes the surface enhanced Raman scattering (SERS) of chiral transition metal sulfide such as tantalum disulfide (TaS2) to recognize chiral enantiomers, and through the synergistic effect of the inherent chiral property of chiral transition metal sulfide and the SERS technology, direct, label-free recognition and accurate quantitative analysis of chiral enantiomers are realized.

[0028] In addition, the present application synthesizes chiral transition metal sulfide by a wet chemical intercalation method, ensures that the enantioselectivity is stable among different batches and has excellent reproducibility, enhances the reliability and repeatability of the chiral recognition method, and has wide applicability and versatility in recognizing different types of chiral enantiomers. In addition, the present application does not need additional bonding strategies, and can directly utilize the local asymmetric sites induced by chiral transition metal sulfide such as chiral tantalum disulfide between the atomic layer and the surface atomic defects to realize stereospecific interaction with the analyte, thereby directly, label-free recognizing different biological chiral enantiomers and performing accurate quantitative analysis. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A schematic diagram of chiral molecules S- / R-MBA inserted into original TaS2 to form chiral TaS2.

[0030] Figure 2 Figure 1 shows the characterization results of chiral TaS2; where (a) is the XRD characterization, (b) is the Raman spectral characterization, and (c) and (d) are both circular dichroism spectral characterizations.

[0031] Figure 3 This is a schematic diagram illustrating the principle of SERS chiral identification; where (a) is a schematic diagram of two-dimensional chiral S- / R-TaS2 recognizing 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 within the M concentration range, (d) showing L-glucose on R-TaS2 at 10 -3 M to 10 -9 SERS spectra within the M concentration range.

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

[0033] Figure 5 This is a schematic diagram of SERS chiral identification of histidine; where (a) shows the SERS spectra of L-histidine and D-histidine on S- / R-TaS2, exhibiting enantioselectivity; and (b) shows the SERS spectra of D-histidine on the S-TaS2 chiral substrate at different concentrations (10). - 3 M to 10 -6 SERS spectra within the range of M), (c) showing L-histidine on the R-TaS2 chiral substrate at different concentrations (10 M). -3 M to 10 -6 (m) is the SERS spectrum within the range of M, and (d) is the linear regression diagram of the measured and actual values ​​of L-histidine within a certain concentration range. Detailed Implementation

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

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

[0036] 1. Limitation of optical property determination: Traditional chiral recognition mainly relies on optical property determination, such as circular dichroism (CD), which distinguishes enantiomers through the interaction between light and matter. However, these methods generally have limited sensitivity, are easily disturbed (such as UV absorption of salt and solvent), and have insufficient precision, especially when dealing with weak chiral signals, weak absorption bands and small chiral differences.

[0037] 2. Indirect detection and probe dependence: Current SERS chiral recognition techniques mostly use indirect detection strategies, which require secondary probes such as chiral selectors to interact stereospecifically with analytes. However, this method can only reflect the change in probe signal and cannot capture the information of the analyte itself, so it is easily disturbed by other substances and has a limited range of chiral enantiomers applicable to this method.

[0038] 3. Label-free SERS chiral recognition: 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 enantiomers to adsorb in a differential manner. However, this recognition method has the problem of preparing asymmetric chiral nanostructures, which currently mainly relies on special surfaces (such as Cu / Ag high Miller index surfaces) or complex methods such as chiral templates, chiral imprints to prepare asymmetric chiral nanostructures. In addition, there is a problem of insufficient affinity between the analyte and the chiral surface, which is due to the weak interaction between many analytes and chiral surfaces, which requires the use of additional bonding strategies (such as electrochemical potential), which limits the effective differentiation of enantiomers and the generation of strong SERS signals.

[0039] Therefore, the present application provides a surface enhanced Raman scattering substrate, wherein the surface enhanced Raman scattering substrate comprises a substrate and a layer of chiral molecule intercalated superlattice material arranged on the surface of the substrate, and the chiral molecule intercalated superlattice material comprises layered transition metal sulfide and chiral molecules embedded between the layers of transition metal sulfide.

[0040] Transition metal dichalcogenides belong to two-dimensional layered materials. The unique gap between layers allows many foreign molecules to be inserted into the gap without destroying the crystal structure of the atomic layers of the two-dimensional layered materials, thereby forming perfect superlattices. By means of chemical intercalation, chiral molecules can be successfully inserted into two-dimensional layered crystals to form chiral intercalation superlattice materials.

[0041] The embodiment of the present application uses the surface enhanced Raman scattering (SERS) of chiral intercalation superlattice materials (i.e. chiral transition metal dichalcogenides) to identify chiral enantiomers. By skillfully utilizing the synergistic effect of the intrinsic chirality of chiral transition metal dichalcogenides and the SERS technology, direct and label-free identification and accurate quantitative analysis of chiral enantiomers are achieved. This is mainly because the local asymmetric sites induced between the atomic layers and the surface atomic defects of chiral transition metal dichalcogenides achieve stereospecific interaction with the analyte, thereby realizing the identification of chiral enantiomers.

[0042] Specifically, the SERS of chiral transition metal dichalcogenides used in the embodiment of the present application has the following technical advantages in identifying chiral enantiomers:

[0043] 1. Different chiral enantiomers can be directly distinguished without labeling, which increases the application range 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 inherent chiral enantiomer specificity of the chiral transition metal dichalcogenide nanostructure is realized through an optimized single-step wet chemical synthesis process without any additional post-processing or modification. The manufacturing process is simple, and has the advantages of low cost and easy manufacturing. The chiral transition metal dichalcogenide is synthesized by a wet chemical intercalation method, which ensures that the enantioselectivity is stable among different batches and has excellent reproducibility, thereby enhancing the reliability and repeatability of the chiral enantiomer identification method.

[0045] 3. The spectral information of the target chiral enantiomer is allowed to be identified while the interference of complex biological matrix is eliminated, thereby directly and label-free identifying different biological chiral enantiomers and performing accurate quantitative analysis, which improves the accuracy of identification.

[0046] 4. L- / D-glucose and L- / D-histidine are selected as chiral pairs to form a model, and SERS is used to study the obvious enantiomer-specific interaction between chiral enantiomers and chiral TaS2, thereby forming a unique SERS peak pattern and peak intensity ratio change, realizing the identification of chiral enantiomers, and demonstrating the wide applicability and versatility of the method in identifying different types of chiral enantiomers.

[0047] 5. Without additional bonding strategies, the chiral transition metal sulfide such as chiral ditantalum sulfide can be directly used to induce the formation of local asymmetric sites between atomic layers and surface atomic defects, to realize stereospecific interaction with analytes, thereby directly and label-free recognizing different biological chiral enantiomers and performing accurate quantitative analysis.

[0048] In an embodiment, the transition metal sulfide is TaS2, and the chiral molecule is S-MBA and R-MBA.

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

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

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

[0052] In an embodiment, the preparation method of the chiral TaS2 comprises the following steps:

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

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

[0055] The embodiment of the present application synthesizes chiral TaS2 by a wet chemical intercalation method, and realizes direct and label-free recognition and accurate quantitative analysis of L- / D-glucose and L- / D-histidine enantiomers by skillfully utilizing the synergistic effect of the intrinsic chirality of TaS2 and SERS technology. The preparation method of chiral TaS2 has the advantages of simple preparation process, low cost and easy preparation. And the chiral TaS2 is synthesized by the wet chemical intercalation method, which ensures that the enantioselectivity of the chiral TaS2 remains stable among different batches and has excellent reproducibility, thereby enhancing the reliability and repeatability of the chiral recognition method.

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

[0057] In an embodiment, the substrate is composed of a silicon layer, a silicon dioxide layer and a metal layer which are sequentially stacked, and the metal layer is arranged in close contact with the chiral molecule intercalated superlattice material layer.

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

[0059] The embodiment of the present application provides a preparation method of the surface enhanced Raman scattering substrate as described above, which comprises the following steps:

[0060] providing a substrate;

[0061] forming a chiral molecule intercalated superlattice material layer on the substrate to obtain the surface enhanced Raman scattering substrate.

[0062] In an embodiment, the step of forming a chiral molecule intercalated superlattice material layer on the substrate specifically comprises:

[0063] configuring a chiral molecule intercalated superlattice material solution;

[0064] coating the chiral molecule intercalated superlattice material solution on the substrate, and performing annealing treatment to obtain the chiral molecule intercalated superlattice material layer.

[0065] In an embodiment, the chiral molecule intercalated superlattice material solution is configured by dissolving chiral molecule intercalated superlattice material in a solvent, and the solvent is at least one of water and isopropyl alcohol.

[0066] In an embodiment, the temperature of the annealing treatment is 50-70℃ (such as 60℃), and the time is 10-14h (such as 12h).

[0067] The embodiment of the present application provides a chiral recognition method, which comprises the following steps:

[0068] The surface-enhanced Raman scattering substrate described in the embodiments of the present application is provided;

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

[0070] Performing Raman scattering detection to realize recognition of the chiral enantiomer.

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

[0072] The chiral recognition method provided in the embodiments of the present application has the following technical advantages:

[0073] 1. Direct label-free recognition and quantification: by combining chiral transition metal dichalcogenides (for example, chiral TaS2) with SERS technology, the local asymmetric sites induced between the atomic layer and the surface atomic defects of chiral TaS2 are utilized to realize stereospecific interaction with the analyte (i.e., the chiral enantiomer to be detected), thereby directly and label-free recognizing different biological chiral enantiomers and performing accurate quantitative analysis.

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

[0075] 3. Model chiral pair verification and application examples: L-glucose and D-glucose are selected as a chiral pair model, and SERS research reveals obvious enantiomeric specific interaction between the two and chiral TaS2, forming a unique SERS peak pattern and peak intensity ratio change. This method is successfully applied to chiral recognition of L-glucose and D-glucose in saliva samples, fully verifying its practical value in the biomedical field.

[0076] 4. Method universality and multifunctionality display: further detection of enantiomeric specific recognition of another chiral pair L-histidine and D-histidine displays the wide applicability and multifunctionality of the method in recognizing different types of chiral molecules.

[0077] The present application will be described in detail through specific embodiments.

[0078] 1. Preparation of S- / R-TaS2 chiral molecule intercalated superlattice material

[0079] Preparation procedure of S-TaS2 chiral intercalated superlattice material: 100 mg of H-TaS2 (pure TaS2) powder was placed in a glass vial. Under N2 protection, 4 mL of S-MBA was added to the vial to obtain a mixture. The mixture was stirred at 65 °C under N2 atmosphere for 72 hours. After stirring, the reaction system was centrifuged at 11000 rpm for 10 min, and the chiral intercalated superlattice material to be purified was collected. Subsequently, the chiral intercalated superlattice material to be purified was redispersed in isopropanol, and the dispersion / centrifugation was repeated three times, followed by thorough washing. Finally, the purified chiral intercalated superlattice material was 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 that of S-TaS2 chiral molecular intercalation superlattice material, except that S-MBA is replaced by R-MBA.

[0081] like Figure 1 As shown, S-MBA and R-MBA chiral molecules were successfully intercalated into the van der Waals spacing of the layered original TaS2, thus forming a chiral molecular intercalation superlattice material (i.e., chiral TaS2). X-ray diffraction (XRD) analysis revealed that, compared to H-TaS2, the diffraction peaks of chiral S- / R-TaS2 shifted significantly towards lower diffraction angles. The XRD results indicate no difference between the S-TaS2 and R-TaS2 chiral materials, suggesting that the intercalation of different chiral enantiomers does not affect the structure of the chiral superlattice. Figure 2 (a) Raman spectroscopy further confirmed that the chiral S- / R-TaS2 material retains the intrinsic lattice structure of the intrinsic H-TaS2 crystal, see [reference]. Figure 2 (b) Intrinsic H-TaS2 crystals typically have a diameter of approximately 284 cm⁻¹. -1 The manifestation at point E 1 2 g In-plane phonon modes, at approximately 402 cm -1 The location is represented as out-of-plane A 1 g Pattern. These properties are well preserved in S- / R-TaS2 chiral materials, despite the increase in strength, A 1 g The mode's minute displacement reached 400cm -1 A 1 gThis blue shift in the mode indicates the enhancement of in-plane vibrational modes after intercalation and is attributed to the suppression of the long-range Coulombic interlayer interaction. These observations suggest that there is no identifiable phase change after intercalation. Moreover, there is no significant difference between S-TaS2 and R-TaS2 chiral superlattices, indicating that they have similar structures. The chirality induction of S- / R-TaS2 superlattices is finally confirmed by circular dichroism (CD) studies. The intrinsic H-TaS2 exhibits a minimal CD response, while the corresponding S- / R-TaS2 chiral superlattices exhibit significantly opposite CD absorption characteristics in the wavelength range of 250-280 nm. This highlights the significant preference for absorption of different circularly polarized light, thereby verifying the successful incorporation of selected chiral molecules into the host layers. In comparison with the pure chiral molecules, the CD spectral peak positions of the chiral superlattices remain unchanged, as shown in Figure 2 Figs. (c)-(d). This observation indicates that the inherent molecular structure and chiral optical properties are essentially unaffected, which can be attributed to the non-covalent van der Waals interactions between the host and chiral intercalation agents. In-depth analysis by high-resolution scanning tunneling electron microscopy (STEM) found that the interlayer distance increased from the original to (see Figure 1 ), and the planes of S- / R-TaS2 have essentially the same characteristics as the intrinsic H-TaS2. This demonstrates that even after intercalation, the H-TaS2 host layer can still maintain its original crystal structure, which is crucial for preserving and integrating its inherent electronic properties and molecular chirality. Nitrogen adsorption-desorption studies found that the large amount of interlayer expansion increased the surface area of the S- / R-TaS2 chiral superlattices, and the enhanced specific surface area not only supports the interlayer expansion, but also facilitates the increase in the number of active sites. There is additional space within the layer for the analyte to contact the chiral substrate, which is particularly important in chiral recognition.

[0082] 2、SERS-based chiral recognition of L- / D-glucose

[0083] 1) Preparation of S-TaS2 surface-enhanced Raman scattering substrate: spin-coat the S-TaS2 aqueous solution prepared in step 1 on a substrate composed of a silicon layer, a silicon dioxide layer, and an Au layer (denoted as Si / SiO2 / Au) arranged in sequence, and then anneal at 60°C for 12 h to obtain an S-TaS2 layer on the substrate, thereby obtaining an S-TaS2 surface-enhanced Raman scattering substrate, as shown in Figure 3 Fig. (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 was spin-coated onto a substrate (denoted as Si / SiO2 / Au) consisting of a silicon layer, a silicon dioxide layer, and an Au layer stacked sequentially. After annealing at 60°C for 12 hours, an R-TaS2 layer was obtained on the substrate, thus obtaining a surface-enhanced Raman scattering substrate with R-TaS2 as the substrate. See [link to documentation]. Figure 3 As shown in (a).

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

[0086] Figure 3 (a) shows a schematic diagram illustrating the principle of using SERS to identify chiral enantiomers on an S- / R-TaS2 chiral superlattice. L- / D-glucose was selected as a typical chiral enantiomer. First, chiral enantiomer selection and recognition tests were performed on an achiral pristine H-TaS2 substrate (formed on Si / SiO2 / Au). 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 supporting chiral molecules. Subsequently, tests were conducted on an S- / R-TaS2 chiral superlattice. When L- / D-glucose came into contact with the S- / R-TaS2 chiral superlattice substrate, enantiomer-specific adsorption was observed, and clearly distinguishable SERS molecular spectra appeared. (See figure). Figure 3 (b) Five SERS spectral replicates were performed for each sample, and the relative standard deviations (RSDs) for R-TaS2 were calculated to be approximately 2.3–2.5%, and for S-TaS2, approximately 2–2.4%. These results demonstrate the high level of spectral reproducibility of this invention. For quantitative analysis, chiral S-TaS2 substrates were analyzed from 4 × 10⁻⁶... -9 -4×10 -3 SERS measurements were performed on D-glucose at different concentrations in M. S-TaS2 showed an enantioselective response to D-glucose in the range of 650-670 cm⁻¹. -1 and 860-880cm -1 A distinct SERS peak appears between the two points. Figure 3 The response to L-glucose was not significant. Then, the limit of detection (LOD) was calculated, and the strongest SERS peak (650-670 cm⁻¹) was determined. -1 The intensity was fitted to the logarithmic concentration of D-glucose. A positive linear correlation was observed with increasing concentration, showing a high R-value of 0.985–0.990. 2values of 0.88-0.90 nM. The chiral R-TaS2substrate was also investigated under the same conditions and showed similar but opposite trends. The SERS signal showed a high response to the change in L-glucose concentration. By fitting the 650-670 cm -1 peak intensity to the logarithmic concentration of L-glucose, a linear correlation was obtained. The R 2 values were determined to be 0.989-0.992 and the LOD was calculated to be about 0.80-0.82 nM, see Figure 3 in (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 increased surface roughness induced by this, etc.

[0087] The enantioselectivity originated from the stereospecific interactions between glucose and the chiral structure of S- / R-TaS2, which resulted in the adsorption of glucose enantiomers on S- / R-TaS2with different geometrical shapes and different degrees of interaction affinity. The anisotropic surface defects and chirality found on the chiral surface of S- / R-TaS2created an inherent asymmetric molecular environment, which was a key factor to induce stereospecific interactions between the analyte and the chiral surface.

[0088] To demonstrate the practical feasibility of the invention, the present invention performed multiple measurements on the two enantiomers in a glucose mixture composed of L-glucose and D-glucose and accurately estimated their relative composition.

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

[0090] where C DG and C LG are the relative concentrations of D-glucose and L-glucose, respectively. First, the SERS spectra of the S-TaS2substrate were recorded at D-glucose concentrations from 0% to 100% in the glucose mixture. Figure 4 in (a) shows that the SERS intensity also increases as the concentration of D-glucose in the glucose mixture increases. Next, a calibration curve was developed using the I 660 peak intensity at different ee% ratios from 0 to 100% in the glucose mixture. The corresponding calibration curve showed a high degree of linearity, with R 2 values of about 0.995, see Figure 4Figure 6. The measured values of the enantiomeric excess of the two binary mixtures consisting of 25% and 50% D-glucose are in good agreement with the known values. The measured values show a strong correlation with the known values with only about 0.8-1.0% absolute difference, see Figure 4 Figures 7 (b), (d). Next, the stability of the S- / R-TaS2 chiral substrate for glucose sensing was investigated. As shown in Figures 7 (e), (f), the SERS spectra were recorded in air environment for 0-60 days. After 2 months, the SERS peak intensities show limited degradation, indicating that the S- / R-TaS2 chiral substrate is quite stable. Figure 4

[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. To verify the versatility of the technique by studying another chiral pair, L- and D-histidine, SERS chiral discrimination of L- and D-histidine was investigated. The SERS detection of L- and D-histidine enantiomers was performed on S- / R-TaS2 chiral substrates. The SERS spectra show enantiospecific molecular patterns specific to L- and D-histidine. As shown in Figure 8 (a), D-histidine shows preferential adsorption and binding to the S-TaS2 chiral substrate and exhibits a significant SERS response. By regression analysis of the SERS spectra of D-histidine at different concentrations, D-histidine can be quantitatively analyzed with a linear precision of 0.958-0.962 and a LOD of 2.2-2.4 μΜ, as shown in Figure 8 (b). Figure 5 Figure 5 Figure 8 (c). While L-histidine shows enantioselectivity to the R-TaS2 chiral substrate and exhibits a significant SERS response. SERS analysis can quantitatively analyze L-histidine with a linear precision of 0.968-0.972 based on regression analysis and a LOD of 0.88-0.92 μΜ, as shown in Figure 8 (d). By establishing a calibration curve close to an ideal line between the measured values and the actual values of L-histidine, the composition measurement results of two samples of 20 μΜ and 1 mM L-histidine are in good agreement with the actual values, as shown in Figure 8 (e). Figure 5 Figure 5

[0093] ​​​​In summary, the present application provides a surface-enhanced Raman scattering substrate and a preparation method and a chiral recognition method thereof, the present application combines chiral transition metal disulfide and SERS technology, uses the local asymmetric site induced by chiral transition metal disulfide between the atomic layer and the surface atomic defect, realizes the stereospecific interaction with the analyte, thereby directly and unlabeled recognizing different biological enantiomers, and performing accurate quantitative analysis. The chiral recognition technology of the present application effectively overcomes the limitations of the existing chiral recognition technology in sensitivity, universality, anti-interference ability and operation simplicity, and significantly improves the recognition efficiency and accuracy. The specific performance is as follows: (1) has very high detection sensitivity, can detect the concentration of nanomolar level of chiral molecules, such as the detection limit of D- and L-glucose is about 0.88-0.90nM and 0.80-0.82nM respectively; (2) 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 SERS spectrum repeated measurements is low (about 2.3%-2.4%), which verifies the high spectral reproducibility of the experiment; (4) has wide application prospect, is suitable for analysis chemistry, nanoscience, biomedical diagnosis, environmental monitoring, food safety, pharmaceutical industry and other fields, provides an efficient and accurate tool for the recognition and analysis of chiral molecules, and is expected to promote the scientific research, technical innovation and industrial development in related fields.

[0094] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can improve or change it according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A surface enhanced Raman scattering substrate, characterized by, The surface-enhanced Raman scattering substrate comprises a substrate and a chiral molecule intercalated superlattice material layer arranged on the surface of the substrate, the chiral molecule intercalated superlattice material comprising layered transition metal sulfide and chiral molecules intercalated between the transition metal sulfide layers; The transition metal sulfide is TaS2, the chiral molecules are S-MBA and R-MBA, the S-MBA is S-alpha-methylbenzylamine, and the R-MBA is R-alpha-methylbenzylamine.

2. The surface enhanced Raman scattering substrate according to claim 1, wherein The thickness of the chiral molecule intercalated superlattice material layer is 20-50 nm.

3. The surface enhanced Raman scattering substrate of claim 1, wherein, The substrate is composed of a silicon layer, a silicon dioxide layer and a metal layer arranged in sequence, and the metal layer is arranged in close contact with the chiral molecule intercalated superlattice material layer.

4. The surface enhanced Raman scattering substrate according to claim 3, wherein The material of the metal layer is Au, Ag or Cu.

5. A method of producing a surface-enhanced Raman scattering substrate as claimed in any one of claims 1 to 4, characterized in that, The method comprises the steps of: providing a substrate; forming a chiral molecule intercalated superlattice material layer on the substrate to obtain the surface-enhanced Raman scattering substrate.

6. The method of making a surface-enhanced Raman scattering substrate of claim 5, wherein, The step of forming a chiral molecule intercalated superlattice material layer on the substrate specifically comprises: configuring a chiral molecule intercalated superlattice material solution; coating the chiral molecule intercalated superlattice material solution on the substrate, and performing annealing treatment to obtain the chiral molecule intercalated superlattice material layer.

7. The method of making a surface enhanced Raman scattering substrate according to claim 6, wherein, The chiral molecule intercalated superlattice material solution is configured by dissolving chiral molecule intercalated superlattice material in a solvent, and the solvent is at least one of water and isopropyl alcohol; The annealing treatment is performed at a temperature of 50-70℃ for 10-14 hours.

8. A chiral recognition method characterized by, The method comprises the steps of: providing the surface-enhanced Raman scattering substrate according to any one of claims 1-4; adding a chiral enantiomer to be detected to the chiral molecule intercalated superlattice material layer of the surface-enhanced Raman scattering substrate; performing Raman scattering detection to realize recognition of the chiral enantiomer; The chiral enantiomers are L-glucose and D-glucose, or the chiral enantiomers are L-histidine and D-histidine.

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