PDMS flexible sers substrate based on aao nanotemplate replication and in-situ gold nanostructure growth, and preparation method and use thereof
By replicating AAO nanotemplates and growing in situ gold nanostructures on the PDMS surface to form biomimetic tentacled structures, the problems of limited stability and enhancement effect of SERS substrates were solved, and efficient and rapid detection of target molecules was achieved.
Patent Information
- Application Number
- CN202611383131.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-08
- Publication Date
- 2026-11-06
AI Technical Summary
Existing SERS substrates suffer from poor nanoparticle stability, limited enhancement effect, and complex detection on flexible substrates. Traditional nanoparticle substrates are prone to detachment and aggregation, while two-dimensional substrates have a small effective detection area, insufficient molecular adsorption capacity, and complex detection procedures, which are not conducive to rapid on-site detection.
A regular arrangement of biomimetic tentacle-like nanostructures was formed on the surface of PDMS using AAO nanotemplate replication technology. A two-step in-situ gold nanostructure growth method was used to achieve a stable bond between the gold nanostructure and the PDMS nanostructure, thus preparing a flexible PDMS SERS substrate.
It increases the specific surface area of the substrate and the adsorption capacity of target molecules, reduces nanoparticle shedding and aggregation, forms high-density electromagnetic hot spots, enhances SERS performance, simplifies the detection process, and enables rapid detection.
Smart Images
Figure CN123046058A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biotechnology, specifically to a PDMS flexible SERS substrate based on AAO nanotemplate replication and in-situ gold nanostructure growth, its preparation method, and its applications. Background Technology
[0002] Surface-enhanced Raman scattering (SERS) technology utilizes the localized surface plasmon resonance effect on the surface of noble metal nanomaterials to form regions of strong electromagnetic field enhancement (i.e., "hot spots"), thereby achieving highly sensitive detection of target molecules. Currently, SERS technology is widely used in fields such as food safety, environmental pollutants, biomedicine, and trace drug analysis.
[0003] Existing SERS substrates mainly include noble metal nanoparticle solutions, self-assembled metal nanofilms, and rigid solid substrates. However, in practical applications, the following shortcomings still exist: (1) Traditional nanoparticle-type SERS substrates have poor stability: Currently, gold and silver nanoparticles are often loaded onto the surface of glass, silicon wafers, and polymer substrates through drop-coating, spraying, etc. However, the nanoparticles and the substrate mainly rely on physical adsorption to bind, which easily leads to particle shedding, agglomeration, and changes in surface structure, resulting in a decrease in SERS enhancement performance. (2) Traditional two-dimensional SERS substrates have limited enhancement effects: The surface structure of existing two-dimensional SERS substrates such as glass, silicon wafers, and gold films is relatively flat, and the enhancement effect is only generated by metal films or randomly distributed nanoparticles. Due to the lack of high-density three-dimensional nanostructures, they have the following problems: small effective detection area; insufficient molecular adsorption capacity; limited number of electromagnetic hot spots; which limits the SERS enhancement ability. (3) Existing flexible SERS substrates lack direct detection capabilities: Currently, some SERS substrates require: sample pre-enrichment; nanoparticle mixing; substrate transfer; multi-step processing; and complex detection process, which is not conducive to rapid on-site detection.
[0004] AAO nanotemplates are alumina materials with a regular array of nanopores. Due to their advantages such as tunable pore size, regular arrangement, and low fabrication cost, AAO is frequently used for nanostructure replication. Existing technologies utilize PDMS to replicate AAO pore structures to obtain nanopillars, nanopores, or nanoarray structures; however, pure PDMS nanostructures lack noble metal reinforcement materials, resulting in limited SERS performance. Summary of the Invention
[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a biomimetic tentacle-shaped PDMS flexible SERS substrate based on AAO nanotemplate replication and in-situ gold nanostructure growth, as well as its preparation method and applications, to overcome the deficiencies of the prior art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: One aspect of the present invention provides a method for preparing a flexible PDMS SERS substrate based on AAO nanotemplate replication and in-situ gold nanostructure growth, the method comprising the following steps: 1) Modify the AAO template with fluorosilane, clean and dry; 2) Apply the PDMS prepolymer onto the AAO template, perform vacuum degassing, and cure at 60-90℃; 3) Peel off to obtain the PDMS substrate; 4) The PDMS substrate undergoes oxygen plasma surface activation treatment; 5) Immerse the PDMS substrate in a silane coupling agent solution for surface modification, then clean and dry; 6) Mix the chloroauric acid trihydrate solution with the trisodium citrate solution, and add sodium borohydride solution under stirring to obtain mixture one; the molar ratio of chloroauric acid to trisodium citrate is 1:0.5-5; the molar ratio of chloroauric acid to sodium borohydride is 1:1-5; 7) Add one drop of the mixture to the PDMS substrate, wash, and dry; 8) Mix chloroauric acid trihydrate solution with trisodium citrate solution, and add sodium borohydride solution under stirring to obtain mixture II; the molar ratio of chloroauric acid to trisodium citrate is 1:0.5-5; the molar ratio of chloroauric acid to sodium borohydride is 1:1-5; 9) Add two drops of the mixture to the PDMS substrate, wash, and dry.
[0007] Further, step 1) specifically involves: cleaning the AAO template, placing the cleaned AAO template in a closed reaction environment, placing a fluorosilane-based surface modification reagent near the template, subjecting the reaction system to reduced pressure, allowing it to stand, cleaning, and drying.
[0008] Furthermore, the AAO template has a pore size of 20-50 nm and a pore depth of 5-40 μm, and the surface modification reagent can be selected from any one of FOTS, FDTS, and FAS-17.
[0009] Further, in step 4), the ion surface activation treatment is performed with the following parameters: power: 50-80W; time: 30-100s.
[0010] Furthermore, the aminosilane coupling agent in step 5) is selected from any one of APTMS, APTES, AEAPTMS, and APDMES.
[0011] Further, in step 5), the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface is 1:0.02-0.2; the reaction is carried out at room temperature for 0.5-5 hours.
[0012] Furthermore, the cleaning method in steps 7) and 9) is as follows: after holding for 10 to 100 seconds, rinse with ultrapure water, and the drying method is to dry at room temperature.
[0013] Another aspect of the present invention provides a PDMS flexible SERS substrate prepared by the above method.
[0014] Another aspect of the present invention provides the use of the above-described PDMS flexible SERS substrate for SERS detection.
[0015] Furthermore, the intended use refers to the use of drugs in biological samples for quantitative and / or qualitative analysis.
[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) By using AAO nanotemplate replication technology, a regularly arranged biomimetic tentacled nanostructure is formed on the surface of PDMS, which improves the specific surface area of the substrate and the adsorption capacity of target molecules. (2) Through a two-step in-situ gold nanostructure growth method, the gold nanostructure and PDMS nanostructure are stably combined, reducing the problems of traditional nanoparticle shedding and aggregation; (3) High-density electromagnetic hotspots are generated by combining three-dimensional nano-tent structures with gold nanostructures to improve SERS enhancement performance; (4) The preparation process of this method is simple, and the sample can be directly dropped onto the substrate surface for detection, which has the potential for rapid detection applications. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the process of the present invention.
[0018] Figure 2 The image shows the SERS spectrum of Au@PDMS loaded with 4-ATP prepared in Example 1.
[0019] Figure 3 Here are the SERS spectra of Example 2: (a) Au@PDMS loaded with sertraline; (b) Au@PDMS loaded with moxifloxacin; (c) Au@PDMS loaded with levetiracetam.
[0020] Figure 4 SERS spectra of Au@PDMS loaded with different concentrations of 2-naphthiophenol prepared in Example 2: (a) Spectra of Au@PDMS loaded with different concentrations of 2-naphthiophenol; (b) SERS spectra of Au@PDMS loaded with different concentrations of 2-naphthiophenol at 1064 cm⁻¹.-1 SERS intensity at the location.
[0021] Figure 5 The SERS spectrum of Au@PDMS loaded with TF-MBA prepared in Example 3.
[0022] Figure 6 This is a comparison of Au@PDMS-loaded 2-naphthiophenol prepared using PS template and AAO template in Example 3.
[0023] Figure 7 The SERS spectrum of Au@PDMS loaded with 4-MPy is shown in Comparative Example 1.
[0024] Figure 8 The SERS spectrum of Au@PDMS loaded with levetiracetam is shown in Comparative Example 2.
[0025] Figure 9 The SERS spectrum of Au@PDMS loaded with moxifloxacin prepared in Comparative Example 3 is shown.
[0026] Figure 10 The SERS spectrum of Au@PDMS loaded with 4-ATP prepared in Comparative Example 4 is shown. Detailed Implementation
[0027] This invention provides a method for preparing a biomimetic tentacle-shaped PDMS flexible SERS substrate based on AAO nanotemplate replication and in-situ gold nanostructure growth, comprising the following steps: 1. The AAO template is pretreated by cleaning it with organic solvents and alcohol solvents in sequence to remove impurities on the template surface, and then cleaned with deionized water to obtain a clean AAO template.
[0028] Wherein: the organic solvent can be selected from any one of acetone, acetonitrile, and ethyl acetate; the alcohol solvent can be selected from any one of anhydrous ethanol, methanol, and isopropanol; the pore size of the AAO template is 20-50 nm and the pore depth is 5-40 μm.
[0029] 2. Place the cleaned AAO template in a closed reaction environment, and place 10-100 μL of fluorinated silane surface modification reagent near the template to allow the modification reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template. Among them, the surface modification reagent can be selected from any one of FOTS, FDTS, and FAS-17.
[0030] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0031] 4. Allow the modified AAO template to stand at room temperature for 0.5–6 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0032] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0033] 6. Mix the PDMS prepolymer and curing agent in a mass ratio of 8:1 to 10:1.
[0034] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0035] 8. Place the PDMS precursor solution at 60-90℃ for 1-5 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0036] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 50-80W; time: 30-100s.
[0037] 10. Prepare 2-20 ml of an aminosilane coupling agent solution with a mass fraction of 1-10%; Among them, the aminosilane coupling agent can be selected from any one of APTMS, APTES, AEAPTMS, and APDMES.
[0038] 11. Immerse the activated PDMS substrate in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups to aminosilane coupling agent on the PDMS surface is 1:0.02-0.2; react at room temperature for 0.5-5 hours.
[0039] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0040] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 2.5–25 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.5–5; under stirring, add 5–25 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:1–5.
[0041] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 10-100 s, wash with ultrapure water, and dry at room temperature.
[0042] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 5-25 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.5-5; under stirring, slowly add 5-25 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:1-5.
[0043] 16. Add the solution prepared in the previous step to PDMS, keep it for 30-300 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0045] Detection method: The analyte solution was dropped onto Au@PDMS for Raman spectroscopy. The SERS enhancement effect was evaluated based on the intensity of the characteristic peak of the reporter molecule. The analytes included, but were not limited to, reporter molecules such as 4-aminothiophenol (4-ATP), 4-mercaptopyridine (4-MPy), 2-naphthiophenol, and tetrafluoro-4-mercaptobenzoic acid (TF-MBA); and included, but were not limited to, complex drugs such as moxifloxacin, sertraline, and levetiracetam.
[0046] The Raman spectrometer used for detection was an OTO Photonics EE2111, with a spectral response range of 250-2000 nm and an optical resolution of 0.2 nm to 13 nm. The Raman spectroscopy detection conditions included: using 785 nm excitation light as the light source, a laser power of 100–500 mW, and an integration time of 1–10 s.
[0047] FOTS: Fluorooctyltriethoxysilane AAO: Alumina materials with a regular nanoporous array structure APTMS: 3-Aminopropyltriethoxysilane Example 1
[0048] 1. The AAO template is pretreated by cleaning it with acetone and anhydrous ethanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0049] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 20 nm and a pore depth of 10 μm.
[0050] 2. Place the cleaned AAO template in a closed reaction environment and place 50 μL of FOTS near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0051] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0052] 4. The modified AAO template was allowed to stand at room temperature for 1 hour to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0053] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0054] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 8:1.
[0055] The PDMS prepolymer and curing agent were purchased from Dow Corning, Japan, and the model number was Sylgard 184.
[0056] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0057] 8. Place the PDMS precursor liquid at 60°C for 5 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0058] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 50W; time: 80s.
[0059] 10. Prepare 2 ml of 1% APTMS solution.
[0060] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface was 1:0.02; the reaction was carried out at room temperature for 5 hours.
[0061] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0062] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 2.5 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.5; under stirring, add 5 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:1.
[0063] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 10 seconds, wash with ultrapure water, and dry at room temperature.
[0064] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 2.5 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.5; under stirring, slowly add 5 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:1.
[0065] 16. Add the solution prepared in the previous step to PDMS, keep it for 30 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0066] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The target substance was 1 mg / ml 4-ATP, and the detection conditions were: laser power 300 mW and integration time 5 s.
[0067] Test results as follows Figure 2 As shown. By Figure 2 As can be seen, when 4-ATP is loaded, the characteristic fingerprint peaks of the 4-ATP molecule are clearly visible in the Raman spectrum. These peaks occur at Raman shifts of approximately 390, 1080, and 1580 cm⁻¹. -1 Significant SERS enhancement was observed at locations such as 1080cm, with an overall high signal-to-noise ratio. -1 The intensity at its peak is as high as approximately 65 × 10⁻⁶. 3 These strong and clear Raman signals fully demonstrate that the prepared Au@PDMS flexible SERS substrate has good surface-enhanced Raman scattering activity, enabling the detection of 4-ATP molecules.
[0068] Example 2 1. The AAO template is pretreated by cleaning it with ethyl acetate and isopropanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0069] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 50 nm and a pore depth of 5 μm.
[0070] 2. Place the cleaned AAO template in a closed reaction environment and place 10 μL of FDTS near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0071] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0072] 4. The modified AAO template was allowed to stand at room temperature for 2 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0073] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0074] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 9:1.
[0075] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0076] 8. Place the PDMS precursor liquid at 90°C for 2 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0077] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 80W; time: 30s.
[0078] 10. Prepare 4 ml of APTES solution with a mass fraction of 5%.
[0079] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface was 1:0.2; the reaction was carried out at room temperature for 1 hour.
[0080] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0081] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 5 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:1; under stirring, add 25 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:5.
[0082] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 100 seconds, wash with ultrapure water, and dry at room temperature.
[0083] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 10 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:2; under stirring, slowly add 25 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:5.
[0084] 16. Add the solution prepared in the previous step to PDMS, keep it for 300s, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0085] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The detection targets were 1 mg / ml sertraline, 1 mg / ml moxifloxacin and 1 mg / ml levetiracetam. The detection conditions were: laser power 500 mW and integration time 1 s.
[0086] Test results as follows Figure 3 As shown. By Figure 3 It can be seen that when sertraline is loaded, the characteristic fingerprint signal of sertraline was successfully extracted from the Raman spectrum. This was observed at Raman shifts of approximately 530, 920, 1350, and 1600 cm⁻¹. -1 Obvious SERS characteristic peaks appeared at locations such as 920 cm⁻¹. -1 The characteristic peak signal is strongest at this location, with a peak intensity reaching approximately 26 × 10⁻⁶. 3 au; located at 530cm -1 Sharp and high-intensity characteristic peaks also appeared at the same location. Although there were some background fluctuations in the spectral baseline, the main characteristic peaks of sertraline molecules were still clearly distinguishable, which further proves that the flexible SERS substrate has a strong universal adsorption capacity for drug molecules and surface-enhanced Raman scattering activity.
[0087] SERS detection of 2-naphthiophenol solutions of different concentrations was performed using the Au@PDMS substrate prepared in Example 2. The detection results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the Raman displacements are approximately 1064, 1380, and 1580 cm. -1 Characteristic fingerprint peaks of 2-naphthiophenol molecules appeared at various locations. As the concentration of 2-naphthiophenol gradually decreased, the intensity of each characteristic peak showed a clear decreasing trend. Figure 4(b) further illustrates the intensity at 1064 cm⁻¹. -1 The quantitative response relationship between the characteristic peak intensity at 10 and the concentration of 2-naphthiophenol. −11 g / mL to 10 −8 Within the concentration range of g / mL, the signal intensity showed a good linear increasing trend with increasing concentration. At 10 g / mL... -13 The characteristic Raman signal of 2-naphthiophenol can still be observed at a concentration of g / mL, indicating that the substrate has high detection sensitivity.
[0088] Example 3 1. The AAO template is pretreated by cleaning it with acetonitrile and methanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0089] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 50 nm and a pore depth of 40 μm.
[0090] 2. Place the cleaned AAO template in a closed reaction environment and place 100 μL of FAS-17 near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0091] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0092] 4. The modified AAO template was allowed to stand at room temperature for 6 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0093] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0094] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 10:1.
[0095] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0096] 8. Place the PDMS precursor liquid at 80°C for 3 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0097] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 60W; time: 60s.
[0098] 10. Prepare 2 ml of 5% APDMES solution.
[0099] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface was 1:0.1; the reaction was carried out at room temperature for 5 hours.
[0100] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0101] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 25 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:5; under stirring, add 10 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:2.
[0102] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 60 seconds, wash with ultrapure water, and dry at room temperature.
[0103] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 25 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:5; under stirring, slowly add 15 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:3.
[0104] 16. Add the solution prepared in the previous step to PDMS, keep it for 90 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0105] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The sample was 1 mg / ml TF-MBA, and the detection conditions were: laser power 500 mW and integration time 1 s.
[0106] Test results as follows Figure 5 As shown. By Figure 5 As can be seen, the characteristic fingerprint peaks of this molecule were clearly presented in the Raman spectrum after loading TF-MBA. These peaks were observed at Raman shifts of approximately 390, 1080, 1330, and 1610 cm⁻¹. -1 Significant SERS enhancement signals were observed at various locations, including 1610 cm⁻¹. -1 The characteristic peak intensity is highest at this location, reaching approximately 65 × 10⁻⁶. 3 Au corresponds to the C=C stretching vibration of the benzene ring. The spectrum exhibits a stable baseline, sharp characteristic peaks, and excellent signal-to-noise ratio, further demonstrating that the Au@PDMS flexible substrate can provide strong SERS enhancement for target molecules with different properties, indicating good applicability.
[0107] To verify the effect of AAO nanotemplates on SERS enhancement performance, under the preparation conditions of Example 3, the AAO template was replaced with a PS template, while other conditions remained unchanged. A PS template control group Au@PDMS flexible SERS substrate was prepared, and SERS was detected using 1 mg / mL 2-naphthiophenol. The detection conditions were: laser power 300 mW, integration time 1 s.
[0108] Test results as follows Figure 6 As shown, the characteristic Raman signal of 2-naphthiophenol was successfully detected on substrates prepared using both templates. Under the same or similar detection conditions, the Au@PDMS flexible SERS substrate prepared using the AAO template exhibited a higher SERS response intensity, indicating that the nanoarray structure formed by AAO template replication is beneficial for improving the SERS enhancement performance of the substrate.
[0109] Comparative Example 1 Compared with Example 1, Comparative Example 1 used an AAO template with a pore size of 5 nm and a pore depth of 50 μm, increased the amount of FDTS and the surface modification time; the PDMS curing conditions were adjusted to 60 °C for 3 h, and the oxygen plasma treatment conditions were adjusted to 60 W for 90 s; the molar ratio of aminosilane coupling agent to hydroxyl groups on the PDMS surface was adjusted to 1:0.25, and the reaction time was shortened to 0.4 h. Simultaneously, the first step of gold nanostructure growth conditions was adjusted to a molar ratio of chloroauric acid, trisodium citrate, and sodium borohydride of 1:1:2, with a treatment time of 9 s; the second step was adjusted to a molar ratio of chloroauric acid, trisodium citrate, and hydroxylamine hydrochloride of 1:2:2, and the treatment time was extended to 330 s.
[0110] 1. Pre-treat the AAO template by cleaning it with acetone and isopropanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0111] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 5nm and a pore depth of 50μm.
[0112] 2. Place the cleaned AAO template in a closed reaction environment and place 110 μL of FDTS near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0113] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0114] 4. The modified AAO template was allowed to stand at room temperature for 6.5 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0115] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0116] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 10:1.
[0117] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0118] 8. Place the PDMS precursor liquid at 60°C for 3 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0119] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 60W; time: 90s.
[0120] 10. Prepare 5 ml of 5% APDMES solution.
[0121] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups to aminosilane coupling agent on the PDMS surface was 1:0.25; the reaction was carried out at room temperature for 0.4 hours.
[0122] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0123] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 5 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:1; under stirring, add 10 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:2.
[0124] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep for 9 seconds, wash with ultrapure water, and dry at room temperature.
[0125] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 10 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:2; under stirring, slowly add 10 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:2.
[0126] 16. Add the solution prepared in the previous step to PDMS, keep it for 330s, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0127] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The target substance was 1 mg / ml 4-MPy, and the detection conditions were: laser power 400 mW and integration time 5 s.
[0128] Test results as follows Figure 7 As shown. By Figure 7 It can be seen that after loading 4-MPy, the obtained Raman spectrum is dominated by low-intensity background signals, mainly in the range of approximately 400–2000 cm⁻¹. -1No clear, distinct, and well-identified characteristic Raman peaks of 4-MPy were observed within the range. Compared with the obvious target molecule characteristic peaks in Examples 1-3, the SERS response of 4-MPy in this comparative example is weaker. The above results indicate that under these preparation conditions, the obtained Au@PDMS flexible composite substrate has a limited SERS detection response to 4-MPy, and its detection performance may be affected by factors such as the adsorption state of the target molecule on the gold surface and the local electromagnetic field distribution.
[0129] Comparative Example 2 Compared with Example 2, the pore size of the AAO template in Comparative Example 2 was adjusted from 50 nm to 60 nm, the amount of FOTS was adjusted from 10 μL to 5 μL, and the surface modification time was shortened from 2 h to 0.4 h. The PDMS curing and oxygen plasma treatment conditions were maintained at 60 °C for 3 h and 60 W for 90 s. APTES was used as the aminosilane coupling agent, but its mass fraction was reduced to 1%, the molar ratio of PDMS surface hydroxyl groups to aminosilane coupling agent was reduced to 1:0.01, and the reaction time was extended to 6.5 h. The first-step growth time of the gold nanostructure was adjusted to 110 s, and the second-step growth time was shortened to 25 s.
[0130] 1. The AAO template is pretreated by cleaning it with ethyl acetate and methanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0131] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 60 nm and a pore depth of 5 μm.
[0132] 2. Place the cleaned AAO template in a closed reaction environment and place 5 μL of FOTS near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0133] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0134] 4. The modified AAO template was allowed to stand at room temperature for 0.4 h to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0135] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0136] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 10:1.
[0137] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0138] 8. Place the PDMS precursor liquid at 60°C for 3 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0139] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 60W; time: 90s.
[0140] 10. Prepare 1 ml of APTES solution with a mass fraction of 1%.
[0141] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups to aminosilane coupling agent on the PDMS surface was 1:0.01; the reaction was carried out at room temperature for 6.5 hours.
[0142] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0143] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 5 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:1; under stirring, add 5 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:1.
[0144] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 110 seconds, wash with ultrapure water, and dry at room temperature.
[0145] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 10 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:2; under stirring, slowly add 10 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:2.
[0146] 16. Add the solution prepared in the previous step to PDMS, keep it for 25 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0147] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The target substance was 1 mg / ml levetiracetam, and the detection conditions were: laser power 500 mW, integration time 3 s.
[0148] Test results as follows Figure 8 As shown. By Figure 8It was found that the Au@PDMS blank substrate did not show obvious characteristic peaks, only a low background signal, and no obvious and clearly attributed characteristic Raman peaks of levetiracetam were observed. These results indicate that under these preparation conditions, the Au@PDMS flexible composite substrate exhibits a weak SERS response to levetiracetam, failing to obtain a clear characteristic signal of the target molecule.
[0149] Comparative Example 3 Compared with Example 3, the AAO template in Comparative Example 3 was adjusted from a pore size of 50 nm and a pore depth of 40 μm to a pore size of 30 nm and a pore depth of 20 μm, and the amount of FAS-17 was reduced to 20 μL; the mass ratio of PDMS prepolymer to curing agent was adjusted to 7:1, and the curing conditions were adjusted to 50 °C and 5.5 h; the oxygen plasma treatment conditions were adjusted to 85 W and 25 s. APTES was used as the aminosilane coupling agent with a mass fraction of 2%, and the molar ratio of PDMS surface hydroxyl groups to aminosilane coupling agent was adjusted to 1:0.2, with a reaction time of 2 h. In the first step of gold nanostructure growth, the molar ratio of chloroauric acid to trisodium citrate was adjusted to 1:0.4, and the molar ratio of chloroauric acid to sodium borohydride was adjusted to 1:6, with a treatment time of 100 s; in the second step, the molar ratio of chloroauric acid to trisodium citrate was adjusted to 1:0.4, and the molar ratio of chloroauric acid to hydroxylamine hydrochloride was adjusted to 1:6, with a treatment time of 60 s.
[0150] 1. The AAO template is pretreated by cleaning it with acetone and anhydrous ethanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0151] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 30 nm and a pore depth of 20 μm.
[0152] 2. Place the cleaned AAO template in a closed reaction environment and place 20 μL of FAS-17 near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0153] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0154] 4. The modified AAO template was allowed to stand at room temperature for 2 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0155] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0156] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 7:1.
[0157] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0158] 8. Place the PDMS precursor liquid at 50°C for 5.5 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0159] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 85W; time: 25s.
[0160] 10. Prepare 10 ml of APTES solution with a mass fraction of 2%.
[0161] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface was 1:0.2; the reaction was carried out at room temperature for 2 hours.
[0162] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0163] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 2 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.4; under stirring, add 30 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:6.
[0164] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 100 seconds, wash with ultrapure water, and dry at room temperature.
[0165] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 2 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.4; under stirring, slowly add 30 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:6.
[0166] 16. Add the solution prepared in the previous step to PDMS, keep it for 60 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0167] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The target substance was 1 mg / ml moxifloxacin, and the detection conditions were: laser power 300 mW and integration time 5 s.
[0168] Test results as follows Figure 9 As shown. By Figure 9It can be seen that after loading moxifloxacin, the obtained Raman spectrum generally exhibits a low-intensity background signal, and the spectral baseline shows a slow decreasing trend with increasing Raman shift. However, no clear and obvious characteristic peaks were observed within the main characteristic Raman shift range of moxifloxacin. Compared with the results in the examples where the target molecule could produce a significant SERS enhancement signal, the SERS response of moxifloxacin in this comparative example is weaker. The above results indicate that under the preparation conditions, the enhanced response of the obtained Au@PDMS flexible composite substrate to moxifloxacin is limited, and a clear characteristic Raman signal of the target molecule was not obtained.
[0169] Comparative Example 4 Compared with Example 3, Comparative Example 4 adjusted the mass ratio of PDMS prepolymer to curing agent to 11:1, increased the curing temperature to 100°C, and shortened the curing time to 0.5 h; the oxygen plasma treatment conditions were adjusted to 45W for 110 s; APTES was used for surface modification, the molar ratio of aminosilane coupling agent to PDMS surface hydroxyl groups was adjusted to 1:0.1, and the reaction time was 4 h. In the first step of gold nanostructure growth, the molar ratio of chloroauric acid to trisodium citrate was increased to 1:6, the molar ratio of chloroauric acid to sodium borohydride was decreased to 1:0.5, and the treatment time was 100 s; in the second step, the molar ratio of chloroauric acid to trisodium citrate was 1:0.5, the molar ratio of chloroauric acid to hydroxylamine hydrochloride was 1:6, and the treatment time was 60 s.
[0170] 1. The AAO template is pretreated by cleaning it with acetone and anhydrous ethanol in sequence to remove impurities from the template surface, followed by cleaning with deionized water to obtain a clean AAO template.
[0171] The AAO template was purchased from Nanjing Xianfeng Nanomaterials, with a pore size of 30 nm and a pore depth of 20 μm.
[0172] 2. Place the cleaned AAO template in a closed reaction environment and place 20 μL of FAS-17 near the template to allow the modifying reagent to evaporate under vacuum conditions and come into full contact with the surface of the AAO template.
[0173] 3. The reaction system is subjected to reduced pressure to allow the fluorinated silane molecules to fully diffuse and deposit on the surface of the AAO template, forming a uniform anti-adhesion modification layer.
[0174] 4. The modified AAO template was allowed to stand at room temperature for 2 hours to react with the fluorosilane molecules on the template surface, thereby improving the hydrophobicity and release properties of the template surface.
[0175] 5. Clean the surface-modified AAO template with deionized water and then dry it.
[0176] 6. Mix the PDMS prepolymer and curing agent at a mass ratio of 11:1.
[0177] 7. Apply the PDMS precursor solution evenly to the surface of the modified AAO template and perform vacuum degassing treatment.
[0178] 8. Place the PDMS precursor liquid at 100℃ for 0.5 hours to cure, then gently peel it off to form a flexible PDMS composite substrate with an AAO template replication structure.
[0179] 9. Perform oxygen plasma surface activation treatment on the replicated PDMS substrate: power: 45W; time: 110s.
[0180] 10. Prepare 10 ml of APTES solution with a mass fraction of 1%.
[0181] 11. The activated PDMS substrate was immersed in a silane coupling agent solution for surface modification, so that the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface was 1:0.1; the reaction was carried out at room temperature for 4 hours.
[0182] 12. The modified PDMS substrate was washed with anhydrous ethanol and deionized water respectively and then dried.
[0183] 13. Mix 5 ml of 10 mM chloroauric acid trihydrate solution with 30 ml of 10 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:6; under stirring, add 2.5 ml of 10 mM sodium borohydride solution to make the molar ratio of chloroauric acid to sodium borohydride 1:0.5.
[0184] 14. Add the solution prepared in the previous step to the PDMS substrate treated with aminosilane coupling agent, keep it for 100 seconds, wash with ultrapure water, and dry at room temperature.
[0185] 15. Mix 5 ml of 5 mM chloroauric acid trihydrate with 2.5 ml of 5 mM trisodium citrate solution to make the molar ratio of chloroauric acid to trisodium citrate 1:0.5; under stirring, slowly add 30 ml of 5 mM hydroxylamine hydrochloride solution to make the molar ratio of chloroauric acid to hydroxylamine hydrochloride 1:6.
[0186] 16. Add the solution prepared in the previous step to PDMS, keep it for 60 seconds, wash with ultrapure water, and dry at room temperature to obtain Au@PDMS flexible composite substrate.
[0187] Test results: Raman spectroscopy was performed on the obtained Au@PDMS flexible SERS substrate. The target substance was 1 mg / ml 4-ATP, and the detection conditions were: laser power 200 mW and integration time 10 s.
[0188] Test results as follows Figure 10 As shown. By Figure 10 It can be seen that after loading 4-ATP, the resulting Raman spectrum was dominated by a low-intensity background signal, and no obvious characteristic Raman peak corresponding to 4-ATP was observed in the range of approximately 400–2000 cm⁻¹. Compared with the results in Example 1, where the same target molecule could produce obvious characteristic peaks, the SERS response in Comparative Example 4 was significantly weakened. The above results indicate that under the preparation conditions, the obtained Au@PDMS flexible composite substrate failed to produce a significant SERS enhancement response to 4-ATP, suggesting that changes in the combination of PDMS replication structure, surface aminosilane modification, and gold nanostructure growth conditions can affect the final SERS detection performance.
[0189] The above embodiments are for illustrating the implementation schemes disclosed in this invention and should not be construed as limiting the invention. Furthermore, various modifications listed herein, as well as variations in the methods and compositions of the invention, will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been specifically described in conjunction with various specific preferred embodiments, it should be understood that the invention should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the invention should be included within the scope of this invention.
Claims
1. A method for preparing a flexible PDMS SERS substrate based on AAO nanotemplate replication and in-situ gold nanostructure growth, the method comprising the following steps: 1) Modify the AAO template with fluorosilane, clean and dry; 2) Apply the PDMS prepolymer onto the AAO template, perform vacuum degassing, and cure at 60-90℃; 3) Peel off to obtain the PDMS substrate; 4) The PDMS substrate undergoes oxygen plasma surface activation treatment; 5) Immerse the PDMS substrate in a silane coupling agent solution for surface modification, then clean and dry; 6) Mix the chloroauric acid trihydrate solution with the trisodium citrate solution, and add sodium borohydride solution under stirring to obtain mixture one; the molar ratio of chloroauric acid to trisodium citrate is 1:0.5-5; the molar ratio of chloroauric acid to sodium borohydride is 1:1-5; 7) Add one drop of the mixture to the PDMS substrate, wash, and dry; 8) Mix chloroauric acid trihydrate solution with trisodium citrate solution, and add sodium borohydride solution under stirring to obtain mixture II; the molar ratio of chloroauric acid to trisodium citrate is 1:0.5-5; the molar ratio of chloroauric acid to sodium borohydride is 1:1-5; 9) Add two drops of the mixture to the PDMS substrate, wash, and dry.
2. The method according to claim 1, characterized in that: Step 1) specifically involves: cleaning the AAO template, placing the cleaned AAO template in a closed reaction environment, placing a fluorosilane-based surface modification reagent near the template, subjecting the reaction system to reduced pressure, allowing it to stand, cleaning, and drying.
3. The method according to claim 2, characterized in that: The AAO template has a pore size of 20-50 nm and a pore depth of 5-40 μm, and the surface modification reagent is selected from any one of FOTS, FDTS, and FAS-17.
4. The method according to claim 1, characterized in that: Step 4) Neutral surface activation treatment: Power: 50-80 W; Time: 30-100 s.
5. The method according to claim 1, characterized in that: The aminosilane coupling agent in step 5) is selected from any one of APTMS, APTES, AEAPTMS, and APDMES.
6. The method according to claim 5, characterized in that: In step 5), the molar ratio of hydroxyl groups and aminosilane coupling agent on the PDMS surface is 1:0.02-0.2; the reaction is carried out at room temperature for 0.5-5 hours.
7. The method according to claim 1, characterized in that: The cleaning method in steps 7) and 9) is as follows: after holding for 10 to 100 seconds, rinse with ultrapure water, and dry at room temperature.
8. The PDMS flexible SERS substrate prepared by the method according to any one of claims 1-7.
9. The use of the PDMS flexible SERS substrate as described in claim 8 for SERS detection.
10. The use according to claim 9, characterized in that, The intended use refers to the use of drugs in biological samples for quantitative and / or qualitative analysis.