A method for preparing superhydrophobic flexible SERS substrates based on glove templates and Cu(OH)2 nanoneedles

Abstract

This invention discloses a method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)₂ nanoneedles, belonging to the field of Raman spectroscopy technology. It solves the technical problems of existing commercial templates being expensive, having limited area, and mostly being hydrophilic materials, thus failing to enrich target molecules and limiting substrate detection sensitivity. The method involves: pouring a PDMS mixture onto the surface of a KD-N-TPE glove template, allowing it to solidify, and then peeling it off to obtain a PDMS substrate with a micron-scale protrusion array structure; depositing Cu by vapor deposition; reacting a mixed solution of NaOH and K₂S₂O₈ with Cu to generate Cu(OH)₂ nanoneedle structures; and then depositing Ag by vapor deposition to obtain the superhydrophobic flexible SERS substrate. The advantages of this invention are: the prepared SERS substrate has high sensitivity and good uniformity, enabling low-concentration detection of target molecules, and is low-cost, low-consumption, and simple to operate.

Description

Technical Field

[0001] This invention belongs to the field of Raman spectroscopy technology, specifically relating to a method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)2 nanoneedles. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) spectroscopy is an important analytical tool with low detection limits, providing adsorbed molecular fingerprints and typically enhancing the Raman signal by 10⁻⁶. 4 -10 9 Therefore, it has enormous application potential in trace substance detection. Template methods can easily and conveniently construct micro- and nano-structures in SERS substrates, but this requires the pre-formation of a finely controlled periodic structure in the template, leading to high template costs and demanding requirements for subsequent processing equipment and environment. Furthermore, commonly used templates are rigid, and the complex sampling process used to directly construct rigid SERS substrates limits the application scope of SERS technology. In addition, commonly used silicon templates and AAO templates are hydrophilic materials, unable to enrich target molecules, thus limiting the substrate's detection sensitivity. Summary of the Invention

[0003] To address the technical problem that existing commonly used templates are hydrophilic materials, which cannot enrich target molecules and limit the detection sensitivity of the substrate, this invention provides a method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)2 nanoneedles. The prepared substrate has high sensitivity, good uniformity, can achieve low-concentration detection of target molecules, and is low in cost, low in consumption, and simple to operate.

[0004] Invention Concept: This invention uses TPE gloves, commonly found in daily life, as a template to prepare a superhydrophobic flexible SERS substrate. TPE gloves are not only inexpensive, but also safe, stable, and easy to store. More importantly, the surface of TPE gloves has a uniform micron-sized pit structure, making them an excellent material for constructing SERS substrates. However, metal nanostructures grown directly on the surface of TPE gloves are prone to detachment. This invention first uses PDMS to replicate the surface structure of the glove, obtaining a PDMS film with a periodic micron-sized protrusion structure, and then uses it as a substrate to deposit a Cu film. Next, Cu(OH)2 nanoneedles are generated by reacting Cu with NaOH and K2S2O8, giving it nanoscale roughness. Finally, Ag nanoparticles are grown on this rough surface by evaporation deposition, resulting in a superhydrophobic flexible SERS substrate that can be used for low-concentration detection.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)2 nanoneedles, comprising the following steps:

[0006] (1) Pour the PDMS mixture onto the surface of the KD-N-TPE glove template, wait for it to solidify and then peel it off to form a negative structure of the glove template surface pit array structure on the PDMS surface, thus obtaining a PDMS substrate with a micron-scale protrusion array structure.

[0007] (2) Cu is deposited on the surface of the PDMS substrate with micron-scale protrusion array structure obtained in step (1) to obtain a Cu-loaded PDMS substrate;

[0008] (3) The PDMS substrate loaded with Cu obtained in step (2) is immersed in a mixed solution of NaOH and K2S2O8, so that the mixed solution of NaOH and K2S2O8 reacts with Cu to generate Cu(OH)2 nanoneedle structure. After cleaning, a PDMS substrate with micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure is obtained.

[0009] (4) Ag is grown by vapor deposition on the surface of the PDMS substrate with micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure obtained in step (3) to obtain a superhydrophobic flexible SERS substrate.

[0010] Furthermore, in step (1), the pits in the pit array structure have a diameter of 120 μm, a depth of 25 μm, and a distance of 60 μm between two adjacent pits.

[0011] Further, in step (1), the PDMS mixture is SYLGARD. TM A mixture of 184PDMS prepolymer and curing agent in a mass ratio of 10:1.

[0012] Further, in step (1), the curing is performed at a temperature of 60°C for 3 hours.

[0013] Furthermore, in step (2), the evaporation deposition is carried out using a JSD-300 evaporation deposition system with a deposition rate of 0.05 nm / s and a deposition time of 60 min.

[0014] Further, in step (3), the mixed solution of NaOH and K2S2O8 is obtained by mixing 2.5 mol / L NaOH solution and 0.1 mol / L K2S2O8 solution in a volume ratio of 1:1.

[0015] Furthermore, in step (3), the reaction temperature is 20°C and the time is 120s.

[0016] Further, in step (3), the cleaning is to clean the surface with ultrapure water with a resistivity of 20.8 MΩ·cm for 20 seconds and then dry it with nitrogen.

[0017] Furthermore, in step (4), the evaporation deposition is carried out using a JSD-300 evaporation deposition system with a deposition rate of 0.05 nm / s and a deposition time of 30 min.

[0018] A superhydrophobic flexible SERS substrate was prepared using the method described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) A three-dimensional nanostructure was constructed using a KD-N-TPE glove template with a pitted surface and Cu(OH)2 nanoneedles, which greatly increased the specific surface area of ​​the substrate and thus improved its sensitivity. By replicating the protrusion structure formed on the PDMS surface and the nanoneedle structure superimposed on the protrusion, the optical path can be greatly increased through reflection, thereby enhancing the Raman scattering signal. The superhydrophobicity of the PDMS / Cu(OH)2 / Ag substrate enables the substrate to enrich the target molecules and can be used for low-concentration trace detection. The good periodicity of the glove template surface structure, the dense growth of nanoneedles, and the dense distribution of Ag nanoparticles on each nanoneedle give the substrate excellent uniformity. The glove template can be cut arbitrarily over a large area to prepare a large-area uniform SERS substrate.

[0021] (2) KD-N-TPE medical gloves are inexpensive, reusable, economical and environmentally friendly. Compared with the method that requires the formation of a fine and controllable periodic structure in the template in advance, the present invention uses KD-N-TPE medical gloves. The overall preparation process is simple and does not require expensive instruments and equipment. It overcomes the shortcomings of traditional SERS substrate preparation process, which is complicated, costly and limited in substrate area. Attached Figure Description

[0022] Figure 1 The flowchart shows the preparation process of the PDMS / Cu(OH)2 / Ag substrate: (a) PDMS is used to replicate the negative structure on the surface of a glove template of model KD-N-TPE; (b) Cu is deposited on the surface of the PDMS substrate with a micron-scale protrusion array structure; (c) Cu(OH)2 nanoneedle structure is generated on the surface of the Cu-loaded PDMS substrate after a chemical reaction; and (d) Ag is deposited on the surface of the PDMS / Cu(OH)2 substrate.

[0023] Figure 2 This is a SEM image of the surface structure of the KD-N-TPE medical glove.

[0024] Figure 3 SEM image of the PDMS substrate surface obtained to replicate the surface structure of KD-N-TPE medical gloves;

[0025] Figure 4SEM image of PDMS / Cu(OH)2 substrate obtained after reacting PDMS / Cu substrate with NaOH and K2S2O8 solution;

[0026] Figure 5 The image shows the FE-SEM image of Ag / Cu(OH)2 nanoneedles after Ag vapor deposition.

[0027] Figure 6 TEM image of Ag / Cu(OH)2 nanoneedles after Ag vapor deposition;

[0028] Figure 7 Raman spectra of crystal violet at different concentrations measured on a PDMS / Cu(OH)2 / Ag substrate;

[0029] Figure 8 10 on PDMS / Cu(OH)2 / Ag substrate -7 mol / L crystal violet and 10 on silicon wafers -1 Raman spectrum of mol / L crystal violet;

[0030] Figure 9 To measure 10 at 100 random locations on a PDMS / Cu(OH)2 / Ag substrate -6 (a) Raman spectrum and (b) 1162 cm⁻¹ spectrum of mol / L crystal violet -1 Intensity distribution of characteristic peaks. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] The method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)2 nanoneedles in this embodiment includes the following steps:

[0034] (1) PDMS replication of glove template surface structure: A PDMS mixture prepared by a mass ratio of PDMS prepolymer and curing agent of 10:1 was poured onto the surface of a KD-N-TPE glove template. After curing at 60℃ for 3 hours, the mixture was peeled off, forming a negative structure of a glove template pit array on the PDMS surface, resulting in a PDMS substrate with a micron-scale protrusion array structure; wherein the diameter of the pits in the pit array structure is 120μm, the depth is 25μm, and the distance between two adjacent pits is 60μm; for example Figure 1 As shown in (a);

[0035] (2) Cu deposition on PDMS substrate surface: Cu was deposited on the surface of the PDMS substrate with micron-scale protrusion array structure obtained in step (1) using a JSD-300 evaporation deposition system. The deposition rate was 0.05 nm / s and the deposition time was 60 min, resulting in a Cu-loaded PDMS substrate, denoted as PDMS / Cu substrate; Figure 1 As shown in (b);

[0036] (3) Formation of Cu(OH)2 nanoneedles on the PDMS / Cu substrate surface: A mixed solution of NaOH and K2S2O8 was prepared by mixing 2.5 mol / L NaOH solution and 0.1 mol / L K2S2O8 solution in a 1:1 volume ratio; the Cu-loaded PDMS substrate obtained in step (2) was immersed in the mixed solution of NaOH and K2S2O8 to react with Cu to form Cu(OH)2 nanoneedle structure. The reaction temperature was 20℃ and the reaction time was 120s; then the substrate was removed, the surface was cleaned with ultrapure water with a resistivity of 20.8 MΩ·cm for 20s, and dried with nitrogen gas to obtain a PDMS substrate with a micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure, denoted as PDMS / Cu(OH)2 substrate; Figure 1 As shown in (c);

[0037] (4) Ag deposition on PDMS / Cu(OH)2 substrate: Ag was deposited on the surface of the PDMS substrate with micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure obtained in step (3) using the JSD-300 evaporation coating system. The deposition rate was 0.05 nm / s and the deposition time was 30 min, resulting in a superhydrophobic flexible SERS substrate, denoted as PDMS / Cu(OH)2 / Ag substrate; Figure 1 As shown in (d).

[0038] Figure 1The flowchart shows the preparation process of the PDMS / Cu(OH)2 / Ag substrate in Example 1. (a) The negative structure of the glove template surface of model KD-N-TPE is replicated by PDMS. (b) Cu is deposited on the surface of the PDMS substrate with the protrusion array structure. (c) Cu(OH)2 nanoneedle structure is generated on the surface of the Cu-loaded PDMS substrate after chemical reaction. (d) Ag is deposited on the surface of the PDMS / Cu(OH)2 substrate.

[0039] Figure 2 The image shows a SEM image of the surface structure of the KD-N-TPE medical glove. The KD-N-TPE medical glove has a micron-scale pit array structure on its surface.

[0040] Figure 3 To replicate the surface structure of KD-N-TPE medical gloves, SEM images of the PDMS substrate were obtained. Figure 3 The surface morphology of the PDMS substrate, which replicates the surface structure of the KD-N-TPE medical glove, is micron-scale protrusion array structure. The specific experimental parameters are the same as experimental steps (1).

[0041] Figure 4 The surface morphology of the PDMS / Cu(OH)2 substrate obtained after the reaction of the PDMS / Cu substrate with NaOH and K2S2O8 solution is shown. Figure 4 The SEM image of Cu(OH)2 nanoneedles was obtained by chemical reaction on the surface of PDMS / Cu substrate. The interlaced Cu(OH)2 nanoneedles are densely distributed on the substrate surface. The specific parameters are the same as in experimental step (3).

[0042] Figure 5 The image shows the FE-SEM image of Ag / Cu(OH)2 nanoneedles after silver evaporation for 30 min. Each nanoneedle is densely covered with Ag nanoparticles. The specific parameters are the same as in experimental step (4).

[0043] Figure 6 The image shows a single Ag / Cu(OH)2 nanoneedle after silver evaporation for 30 min. There are nanoscale gaps between the densely packed Ag particles, forming a high-density SERS hot spot structure. The specific parameters are the same as in experimental step (4).

[0044] Figure 7 Raman spectra of crystal violet at different concentrations measured on a PDMS / Cu(OH)2 / Ag substrate. Figure 7Raman spectra of PDMS / Cu(OH)2 / Ag substrates prepared by depositing copper on a PDMS substrate for 60 min using different concentrations of crystal violet as probe molecules, followed by reaction with NaOH and K2S2O8 for 120 s, and then silver deposition for 30 min, are shown. It can be seen that the lowest detectable concentration of the PDMS / Cu(OH)2 / Ag substrate in this embodiment can reach 10. -8 mol / L.

[0045] Figure 8 10 on PDMS / Cu(OH)2 / Ag substrate -7 mol / L crystal violet and 10 mol / L crystal violet on silicon wafer -1 Raman spectrum of mol / L crystal violet; as shown Figure 8 As shown, through EF = (I SERS *C 0) / (I0*C SERS The enhancement factor of the SERS substrate in this embodiment is calculated to be 1.93 × 10⁻⁶. 7 .

[0046] Figure 9 10 were measured at random locations on a PDMS / Cu(OH)2 / Ag substrate. -6 (a) Raman spectrum and (b) 1162 cm⁻¹ spectrum of mol / L crystal violet -1 Intensity distribution of characteristic peaks; Figure 9 (a) shows the results obtained from 100 random points on a PDMS / Cu(OH)2 / Ag substrate. -6 The Raman spectrum of mol / L crystal violet shows that the enhancement effect is not significantly different at different locations on the substrate. Figure 9 As shown in (b), 1162cm -1 The relative standard deviation of the characteristic peak intensity is 6.20%, which proves that the substrate has excellent uniformity.

Claims

1. A method for preparing a superhydrophobic flexible SERS substrate based on a glove template and Cu(OH)2nanoneedles, characterized in that, Includes the following steps: (1) Pour the PDMS mixture onto the surface of the KD-N-TPE glove template, wait for it to solidify and then peel it off to form a negative structure of the glove template surface pit array structure on the PDMS surface, thus obtaining a PDMS substrate with a micron-scale protrusion array structure. (2) Cu is deposited on the surface of the PDMS substrate with micron-scale protrusion array structure obtained in step (1) to obtain a Cu-loaded PDMS substrate; (3) The PDMS substrate loaded with Cu obtained in step (2) is immersed in a mixed solution of NaOH and K2S2O8, so that the mixed solution of NaOH and K2S2O8 reacts with Cu to generate Cu(OH)2 nanoneedle structure. After cleaning, a PDMS substrate with micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure is obtained. (4) Ag is grown by vapor deposition on the surface of the PDMS substrate with micron-scale protrusion array structure and Cu(OH)2 nanoneedle structure obtained in step (3) to obtain a superhydrophobic flexible SERS substrate.

2. The method according to claim 1, characterized in that, In step (1), the pits in the pit array structure have a diameter of 120 μm, a depth of 25 μm, and a distance of 60 μm between two adjacent pits.

3. The method according to claim 1, characterized in that, In step (1), the PDMS mixture is SYLGARD 184 TM 184PDMS prepolymer and curing agent mixture with a mass ratio of 10:

1.

4. The method according to claim 1, characterized in that, In step (1), the curing is performed at a temperature of 60°C for 3 hours.

5. The method according to claim 1, characterized in that, In step (2), the evaporation deposition is carried out using the JSD-300 evaporation deposition system, with a deposition rate of 0.05 nm / s and a deposition time of 60 min.

6. The method according to claim 1, characterized in that, In step (3), the mixed solution of NaOH and K2S2O8 is obtained by mixing 2.5 mol / L NaOH solution and 0.1 mol / L K2S2O8 solution in a volume ratio of 1:

1.

7. The method according to claim 1, characterized in that, In step (3), the reaction temperature is 20°C and the time is 120s.

8. The method according to claim 1, characterized in that, In step (3), the cleaning process involves cleaning the surface with ultrapure water with a resistivity of 20.8 MΩ·cm for 20 seconds and then drying it with nitrogen.

9. The method according to claim 1, characterized in that, In step (4), the evaporation deposition is carried out using the JSD-300 evaporation deposition system, with a deposition rate of 0.05 nm / s and a deposition time of 30 min.

10. A superhydrophobic flexible SERS substrate, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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