Nanopaper SERS (Surface Enhanced Raman Scattering) detection platform based on cicada wing shape and preparation method thereof

Abstract

The invention relates to a cicada-wing-shape-based nanopaper SERS (Surface Enhanced Raman Scattering) detection platform and a preparation method thereof.A cicada-wing-shaped bionic structure and nanopaper are effectively combined through three steps of preparing a cicada-wing-shaped PDMS (Polydimethylsiloxane) mold, preparing an initial nanopaper platform and preparing the cicada-wing-shape-based nanopaper SERS detection platform, so that integrated preparation is realized; a bionic three-dimensional structure is fully utilized, extra binding sites are generated to detect molecules so as to generate more effective hot spots, and the SERS detection effect is improved.

Description

Technical Field

[0001] The present invention relates to the field of Raman detection technology, and in particular to a nanopaper SERS detection platform based on a cicada wing shape and a preparation method thereof. Background Art

[0002] In the current field of science and technology, surface enhanced Raman spectroscopy (SERS) technology has shown broad application prospects in chemical analysis, biomedical diagnosis, and environmental monitoring due to its high sensitivity and high resolution. As a new type of SERS substrate material, nanofibrillated cellulose paper (nanopaper) has attracted widespread attention due to its optical transparency and low optical haze.

[0003] However, existing SERS detection methods, such as in-situ growth of plasmon materials and direct mixing measurement methods, although they can meet the detection needs to a certain extent, still have some significant limitations. These methods require further chemical reaction processes to generate SERS plasma, which is complicated and time-consuming to operate. More importantly, these methods cannot provide nanopaper platforms (NanoPADs) with integrated noble metal nanoparticles, thus limiting the application scope and efficiency of SERS technology.

[0004] In recent years, three-dimensional (3D) plasmonic platforms have significantly outperformed one-dimensional or two-dimensional plasmonic nanostructures in SERS effects by generating additional binding sites to detect molecules to produce more effective hotspots. In particular, the unique three-dimensional structure of cicada wings, which originate from a common arthropod, provides a new bionic design idea for SERS substrates. However, how to effectively combine this bionic structure with nanopaper to achieve integrated preparation is still a major challenge facing current technology. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a nanopaper SERS detection platform based on the shape of a cicada wing and a preparation method thereof.

[0006] To achieve the above objectives, this application is implemented through the following technical solutions:

[0007] The present application provides a method for preparing a nanopaper SERS detection platform based on a cicada wing shape, comprising the following steps:

[0008] A. Preparation of PDMS mold in the shape of cicada wings:

[0009] A1. Mix the PDMS prepolymer and the curing agent in a ratio of 8:1 to 12:1, stir evenly, let stand, remove bubbles, and obtain a PDMS mixture;

[0010] A2, pouring the PDMS mixture obtained in step A1 into a container paved with cicada wings, and letting it stand to remove bubbles in the PDMS mixture;

[0011] A3. Place the PDMS mixture and cicada wings in an oven at 55°C to 65°C for drying and take them out;

[0012] A4, separate the cured PDMS from the cicada wing mold, rinse the cured PDMS with deionized water, and dry it with nitrogen to obtain a PDMS mold in the shape of a cicada wing;

[0013] B. Preparation of initial nanopaper platform:

[0014] B1, adding deionized water to the nanocellulose gel and mixing thoroughly to prepare a nanocellulose aqueous solution with a solid mass percentage of 0.1%;

[0015] B2, filtering the nanocellulose aqueous solution in step B1 to obtain a gel-like nanopaper;

[0016] B3, soaking the gel-like nanopaper in step B2 in the MPTMS solution, and then filtering after sufficient soaking to obtain the MPTMS-modified nanopaper platform;

[0017] C. Preparation of nanopaper SERS detection platform based on cicada wing shape:

[0018] C1, coating the AuNPs solution on the PDMS mold with a cicada wing shape until the mold is completely covered;

[0019] C2, transfer the cicada wing-shaped PDMS mold covered with AuNPs onto the MPTMS-modified nanopaper platform, with the imprinting temperature of 55°C to 65°C, the imprinting time of 5min to 15min, and the pressure of 900KPa to 1100KPa;

[0020] C3. Dry the printed nanopaper platform to obtain a nanopaper SERS detection platform based on the cicada wing shape.

[0021] As a further improvement of the present application, in step A1, the ratio of the PDMS prepolymer to the curing agent is 10:1.

[0022] As a further improvement of the present application, in step B3, the soaking time is 20 hours to 28 hours.

[0023] As a further improvement of the present application, in step C1, the particle size of the gold nanoparticles in the AuNPs solution is 20 nm to 60 nm.

[0024] As a further improvement of the present application, the AuNPs solution is prepared by the following steps: HAuCl4 Heat the aqueous solution to boiling, and slowly add C 6 H 5 Na 3 O 7 ·2H 2 O solution, fully mix it, and continue to heat the mixed solution under strong stirring, the color of the mixed solution gradually changes from colorless and transparent to black, then to purple-red, and finally to dark red, until the color no longer changes, stop heating, cool it to room temperature, and obtain an AuNPs solution, which is stored at 4°C.

[0025] As a further improvement of the present application, the HAuCl 4 The mass percentage of the solution is 0.04%, and the C 6 H 5 Na 3 O 7 ·2H 2 The mass percentage of the HAuCl solution is 1%. 4 The solution and the C 6 H 5 Na 3 O 7 ·2H 2 The volume ratio of O solution is 15:1 to 17:1.

[0026] As a further improvement of the present application, the HAuCl 4 The solution is 188.5 mL, the C 6 H 5 Na 3 O 7 ·2H 2 O solution is 11.5mL.

[0027] As a further improvement of the present application, in step C2, the coating method is spray coating or spin coating.

[0028] As a further improvement of the present application, in step B2, the thickness of the gel-like nanopaper is 50 μm to 100 μm.

[0029] To achieve the above objectives, the present application also provides a cicada wing-shaped nanopaper SERS detection platform prepared based on the above-mentioned preparation method.

[0030] The present application provides a method for preparing a nanopaper SERS detection platform based on a cicada wing shape. Through the three steps of preparing a cicada wing-shaped PDMS mold, preparing an initial nanopaper platform, and preparing a nanopaper SERS detection platform based on a cicada wing shape, the bionic structure with cicada wings is effectively combined with nanopaper to achieve integrated preparation, fully utilizing the bionic three-dimensional structure, generating additional binding sites to detect molecules to generate more effective hotspots, and improving the SERS detection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the process structure of the preparation method of the cicada wing-shaped nanopaper SERS detection platform of Example 1;

[0032] Figure 2 is a physical schematic diagram of the cicada wing-shaped nanopaper SERS detection platform of Example 1;

[0033] Figure 3 It is a SERS electric field simulation model constructed based on the cicada wing-shaped nanopaper SERS detection platform in Example 4;

[0034] Figure 4 This is the Raman detection curve of rhodamine B and p-aminoazobenzene detected by the cicada wing-shaped nanopaper SERS detection platform prepared in Example 1. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solution of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with specific implementation methods.

[0037] Example 1

[0038] This embodiment provides a method for preparing a nanopaper SERS detection platform based on a cicada wing shape, and its flow diagram is shown in FIG. Figure 1 As shown, the following steps are included:

[0039] A. Preparation of PDMS mold in the shape of cicada wings:

[0040] A1. Mix PDMS prepolymer and curing agent in a mass ratio of 10:1, 18.0 g and 1.8 g respectively, stir thoroughly, mix evenly until fine bubbles appear, let stand, evacuate several times, extract larger bubbles, and obtain a PDMS mixture;

[0041] A2, pouring the PDMS mixture obtained in step A1 evenly into a container paved with cicada wings to form a layered structure, letting it stand, and vacuuming out small bubbles in the PDMS mixture;

[0042] A3, placing the layered structure containing the PDMS mixture and cicada wings in step A2 in a 60° C. oven for at least 3 h, and taking it out;

[0043] A4, separate the cured PDMS from the cicada wing, rinse the cured PDMS with deionized water, and dry it with nitrogen to obtain a PDMS mold in the shape of a cicada wing;

[0044] B. Preparation of initial nanopaper platform:

[0045] B1. Add deionized water to 4 g of nanocellulose slurry with a solid mass percentage of 1%, mix thoroughly, and stir at a speed of 1000 rpm. After it is completely dispersed, a nanocellulose aqueous solution with a solid mass percentage of 0.1% is prepared;

[0046] B2, placing the nanocellulose aqueous solution in step B1 into a suction filtration device with a filter membrane, and filtering for 3h to 4h until no more excess water is contained, to obtain a gel-like nanopaper, the thickness of the gel-like nanopaper is 100 microns;

[0047] B3, soaking the gel-like nanopaper in step B2 in 3-methoxypropyltrimethoxysilane (MPTMS) solution for 24 hours, so that the hydroxyl groups on the gel-like nanopaper will combine with the sulfur groups in MPTMS, and then filtering for 10 minutes to obtain the MPTMS-modified nanopaper platform;

[0048] C. Preparation of nanopaper SERS detection platform based on cicada wing shape:

[0049] C1, 188.5mL HAuCl 4 (0.04%) was injected into a flat-bottomed flask equipped with a magnetic stirrer and heated to boiling. Under continuous stirring and under the guidance of a glass stirring rod, 11.5 mL of 1% C 6 H 5 Na 3 O 7 ·2H 2O solution, fully mix, and continue to heat the mixed solution under strong stirring, the color of the mixed solution gradually changes from colorless and transparent to black, then to purple-red, and finally to dark red, until the color no longer changes, stop heating, cool to room temperature, and obtain an AuNPs solution, the particle size of the gold nanoparticles in the AuNPs solution is 40nm. The AuNPs solution is stored at 4°C;

[0050] C2, spin coating the AuNPs solution on the PDMS mold with a cicada wing shape, and repeat the spin coating operation several times until the cicada wing mold is completely covered;

[0051] C3, transfer the cicada wing-shaped PDMS mold covered with AuNPs onto the MPTMS-modified nanopaper platform, and press at 60°C for 10 min with a pressure of 750 KPa. The sulfur groups in MPTMS will form stable gold-sulfur bonds with gold.

[0052] C4. The printed nanopaper platform is placed in an oven for drying at a drying temperature of 50° C. to obtain a nanopaper SERS detection platform based on the shape of a cicada wing. The schematic diagram of the nanopaper SERS detection platform based on the shape of a cicada wing is shown in FIG. Figure 2 shown.

[0053] Example 2

[0054] The differences between this embodiment and embodiment 1 are as follows:

[0055] A. Preparation of PDMS mold in the shape of cicada wings:

[0056] A1. Mix PDMS prepolymer and curing agent in a mass ratio of 8:1, 14.4 g and 1.8 g respectively;

[0057] A3. The drying temperature is set to 55°C.

[0058] C. Preparation of nanopaper SERS detection platform based on cicada wing shape:

[0059] C2. The cicada wing-shaped PDMS mold covered with AuNPs was transferred to the MPTMS-modified nanopaper platform at a pressing temperature of 55°C, a pressing time of 15 min, and a pressure of 900 KPa.

[0060] Example 3

[0061] The differences between this embodiment and embodiment 1 are as follows:

[0062] A. Preparation of PDMS mold in the shape of cicada wings:

[0063] A1. Mix PDMS prepolymer and curing agent in a mass ratio of 12:1, 21.6 g and 1.8 g respectively;

[0064] A3. The drying temperature is set to 65°C.

[0065] C. Preparation of nanopaper SERS detection platform based on cicada wing shape:

[0066] C2. The cicada wing-shaped PDMS mold covered with AuNPs was transferred to the MPTMS-modified nanopaper platform at a pressing temperature of 65°C, a pressing time of 5 min, and a pressure of 1100 KPa.

[0067] Example 4

[0068] In order to observe the composite structure of cicada wings and AuNPs, the SERS electric field response detection of the cicada wing array in the nanopaper SERS detection platform based on the cicada wing shape prepared in Example 1 was carried out, and the electric field distribution was numerically calculated using COMSOL Multiphysics 6.1 software, and a simplified model was constructed, as shown in Figure 2 . Figure 3 As shown, the light is reflected multiple times between the two parallel AuNPs@cicada wing structures, the optical path is extended, and the electric field intensity is enhanced. Therefore, the volume hotspots are distributed between the two parallel AuNPs@cicada wing structures to form a 3D optical cavity; since a 3D optical cavity is also formed, the laser is trapped in the optical cavity and reflected multiple times, which ensures the efficient utilization of photon energy and excites large volume hotspots. In addition, local hotspots exist in the nanogaps around the AuNPs@cicada wings, indicating strong coupling between large volume hotspots and dense local hotspots. At this time, under laser irradiation, volume hotspots are formed in these gaps, and molecules are easily trapped in the volume hotspots, resulting in a significant enhancement of the Raman signal and achieving ultra-sensitive detection.

[0069] Example 5

[0070] Rhodamine B was dissolved in ethanol to prepare 10 -5 mol / L to 10 -13 mol / L solution as the first analyte; at the same time, p-aminoazobenzene was dissolved in ethanol to prepare a 10 ppb to 50 ppb solution as the second analyte.

[0071] 5 μL of the first and second analytes were dropped onto the cicada wing-shaped nanopaper SERS detection platform prepared in Example 1, dried, and the SERS activity in the reaction area was detected at 600 to 1800 cm -1 The Raman spectrum is obtained within the range, and the Raman curves of the detection results are as follows Figure 4 a and 4c.

[0072] After analysis, the cicada wing-shaped nanopaper SERS detection platform prepared by the technical solution of the present application has excellent detection sensitivity when used as a SERS sensor. The minimum detection limit for rhodamine B can reach 15.8fM, and the minimum detection limit for p-aminoazobenzene can reach 5.21ppb, respectively. Figure 4 b and 4d.

[0073] Although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0074] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present application. They are not intended to limit the scope of protection of the present application. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a nanopaper SERS detection platform based on the shape of a cicada wing. It is characterized in that The steps include: A. Preparation of PDMS mold in the shape of cicada wings: A1. Mix the PDMS prepolymer and the curing agent in a ratio of 8:1 to 12:1, stir evenly, let stand, remove bubbles, and obtain a PDMS mixture; A2, pouring the PDMS mixture obtained in step A1 into a container paved with cicada wings, and letting it stand to remove bubbles in the PDMS mixture; A3. Place the PDMS mixture and cicada wings in an oven at 55°C to 65°C for drying and take them out; A4, separate the cured PDMS from the cicada wing mold, rinse the cured PDMS with deionized water, and dry it with nitrogen to obtain a PDMS mold in the shape of a cicada wing; B. Preparation of initial nanopaper platform: B1, adding deionized water to the nanocellulose gel and mixing thoroughly to prepare a nanocellulose aqueous solution with a solid mass percentage of 0.1%; B2, filtering the nanocellulose aqueous solution in step B1 to obtain a gel-like nanopaper; B3, soaking the gel-like nanopaper in step B2 in the MPTMS solution, and then filtering after sufficient soaking to obtain the MPTMS-modified nanopaper platform; C. Preparation of a nanopaper SERS detection platform based on the shape of a cicada wing: C1. Coat the AuNPs solution on the PDMS mold with a cicada wing shape until the mold is completely covered; C2, transfer the cicada wing-shaped PDMS mold covered with AuNPs onto the MPTMS-modified nanopaper platform, with an imprinting temperature of 55°C to 65°C, an imprinting time of 5min to 15min, and a pressure of 900KPa to 1100KPa; C3. Dry the printed nanopaper platform to obtain a nanopaper SERS detection platform based on the cicada wing shape.

2. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 1, It is characterized in that In step A1, the ratio of the PDMS prepolymer to the curing agent is 10:

1.

3. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 1, It is characterized in that In step B3, the soaking time is 20 hours to 28 hours.

4. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 1, It is characterized in that In step C1, the particle size of the gold nanoparticles in the AuNPs solution is 20 nm to 60 nm.

5. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 4, It is characterized in that The AuNPs solution is prepared by the following steps: HAuCl 4 Heat the aqueous solution to boiling, and slowly add C 6 H 5 Na 3 O 7 ·2H 2 O solution, fully mix it, and continue to heat the mixed solution under strong stirring, the color of the mixed solution gradually changes from colorless and transparent to black, then to purple-red, and finally to dark red, until the color no longer changes, stop heating, cool it to room temperature, and obtain an AuNPs solution, which is stored at 4°C.

6. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 5, It is characterized in that The HAuCl 4 The mass percentage of the solution is 0.04%, and the C 6 H 5 Na 3 O 7 ·2H 2 The mass percentage of the HAuCl solution is 1%. 4 The solution and the C 6 H 5 Na 3 O 7 ·2H 2 The volume ratio of O solution is 15:1 to 17:

1.

7. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 6, It is characterized in that The HAuCl 4 The solution is 188.5 mL, the C 6 H 5 Na 3 O 7 ·2H 2 O solution is 11.5mL.

8. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 1, It is characterized in that In step C2, the coating method is spray coating or spin coating.

9. The method for preparing the cicada wing-shaped nanopaper SERS detection platform according to claim 1, It is characterized in that In step B2, the thickness of the gel-like nanopaper is 50 μm to 100 μm.

10. A cicada wing-shaped nanopaper SERS detection platform prepared by the preparation method according to any one of claims 1 to 9.

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