Flexible SERS (Surface Enhanced Raman Scattering) chip, preparation method thereof and application of flexible SERS chip in detection of marine food pollutants
By loading a carbon dot-silver nanoparticle composite onto the surface of filter paper, a flexible SERS chip was prepared, which solved the detection sensitivity and stability problems of existing filter paper substrates. This enabled the detection of marine food contaminants with high sensitivity and stability, and is suitable for in-situ sampling on complex matrix surfaces.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2026-03-20
- Publication Date
- 2026-04-24
AI Technical Summary
Existing filter paper-based SERS substrates suffer from limitations in detection sensitivity, poor signal uniformity, easy aggregation of AgNPs, insufficient stability, and complex preparation processes, which restrict their application on complex matrix surfaces.
A flexible SERS chip was fabricated by loading a carbon dot-silver nanoparticle composite onto the surface of filter paper and utilizing the synergistic effects of capillary enrichment, electromagnetic enhancement, and chemical enhancement. This simplifies the fabrication process and improves detection sensitivity and stability.
It achieves high sensitivity, signal uniformity and long-term stability, and is suitable for rapid detection of marine food contaminants. The detection limit is as low as 10-15 M, and the enhancement factor is as high as 10¹³. It is suitable for in-situ sampling on complex matrix surfaces.
Smart Images
Figure CN121917528A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of analytical testing technology, and specifically relates to a flexible SERS chip, its preparation method, and its application in the detection of contaminants in marine food. Background Technology
[0002] Surface-enhanced Raman spectroscopy (SERS) is a spectroscopic analysis technique that enhances the Raman scattering signal of molecules based on nanostructured substrates. When the analyte molecule is adsorbed on a rough metal surface or between nanoparticles, its Raman signal can be enhanced by more than a million times. This technique has advantages such as high sensitivity, fast response, non-destructive testing, and strong molecular fingerprint recognition capabilities, and is widely used in fields such as food safety, environmental monitoring, and biomedicine.
[0003] The performance of the SERS substrate directly determines the sensitivity and reliability of the detection, and is the core of SERS technology. Based on the different supporting materials, SERS substrates are mainly divided into two categories: rigid substrates and flexible substrates. While traditional rigid substrates (such as silicon wafers and glass sheets) have good signal enhancement effects, their rigidity makes it difficult to achieve conformal contact with the irregular curved surfaces of food (such as shrimp shells, fish scales, and fruit and vegetable peels), limiting their direct sampling and detection on complex substrate surfaces.
[0004] To overcome the limitations of rigid substrates, researchers have developed various flexible SERS substrates, mainly including those based on polymers (such as PDMS and PET), carbon materials (such as graphene and carbon nanotubes), and cellulose paper (such as filter paper). Among these, filter paper has become a hot research area in flexible SERS substrates due to its natural three-dimensional porous fibrous structure, excellent capillary enrichment ability, low cost, good flexibility, and environmental friendliness. Existing studies often load noble metal nanomaterials such as silver nanoparticles (AgNPs) onto the surface of filter paper fibers, utilizing the localized surface plasmon resonance (LSPR) effect of AgNPs to achieve signal enhancement for the detection of pollutants such as pesticide residues, illegal additives, and mycotoxins.
[0005] However, existing filter paper-based SERS substrates still have the following shortcomings in practical applications: First, most substrates rely on a single electromagnetic enhancement mechanism, lacking the ability to actively enrich analytes and limiting detection sensitivity; second, AgNPs are prone to agglomeration and uneven distribution on the surface of filter paper fibers, resulting in poor signal uniformity and repeatability; third, AgNPs are easily oxidized in air, leading to insufficient substrate stability and affecting long-term storage and use; fourth, the preparation process often involves multiple steps of modification or the addition of reducing agents, which is complex and time-consuming, making it unsuitable for large-scale production and rapid on-site detection applications. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention provides a flexible SERS chip, its fabrication method, and its application in the detection of contaminants in marine food, aiming to simplify the fabrication process, reduce costs, and improve SERS detection sensitivity, signal uniformity, and substrate stability.
[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A method for fabricating a flexible SERS chip includes the following steps: S1. Preparation of carbon dot-silver nanoparticle composite sol: Under stirring conditions, hexadecylpyridine chloride solution and silver nitrate solution are mixed to form a silver ion complex system; then sodium hydroxide solution is added dropwise to the silver ion complex system to react and obtain carbon dot-silver nanoparticle composite sol. S2. Filter paper substrate pretreatment: Cleaning and drying the filter paper; S3. Loading and curing: The carbon dot-silver nanoparticle composite sol prepared in step S1 is loaded onto the surface of the filter paper after pretreatment in step S2, and then dried and cured to form a carbon dot-silver nanoparticle composite coating on the surface of the three-dimensional fiber network of the filter paper, thus obtaining a flexible SERS chip.
[0008] In the above scheme, in step S1, the concentration of the hexadecylpyridine chloride solution is 10-20 mM, the concentration of the silver nitrate solution is 40-50 mM, and the concentration of the sodium hydroxide solution is 0.8-1.2 M.
[0009] In the above scheme, in step S1, the volume ratio of the hexadecylpyridine chloride solution, silver nitrate solution and sodium hydroxide solution is (4-6):(4-6):(1-3).
[0010] In the above scheme, in step S1, the reaction is carried out under light-protected conditions; the stirring rate is 400-600 rpm, and the stirring time is 20-40 minutes.
[0011] In the above scheme, in step S2, the cleaning is performed by sequentially cleaning with ultrapure water and then ultrasonically cleaning with anhydrous ethanol; the drying is performed by using nitrogen gas flow.
[0012] In the above scheme, in step S3, the loading method is to drop the carbon dot-silver nanoparticle composite sol onto the surface of the filter paper, or to immerse it in the carbon dot-silver nanoparticle composite sol.
[0013] In the above scheme, in step S3, the drying and curing treatment is a heat treatment at 50-70°C for 6-10 hours.
[0014] A flexible SERS chip prepared by the method described above.
[0015] Application of a flexible SERS chip prepared by the method described above in the detection of contaminants in marine food.
[0016] In a further technical solution, the application involves in-situ wiping and sampling to detect contaminants on the surface of marine food.
[0017] Through the above technical solution, the flexible SERS chip, its preparation method, and its application in the detection of contaminants in marine food provided by the present invention have the following beneficial effects: 1. This invention provides a flexible SERS chip based on the synergistic effect of capillary enrichment, electromagnetic enhancement, and chemical enhancement. The chip utilizes the capillary action generated by the natural three-dimensional porous fiber structure of the filter paper substrate to achieve active enrichment of target molecules; it leverages the localized surface plasmon resonance effect generated by the carbon dot-silver nanoparticle composite uniformly loaded in the three-dimensional fiber network to provide high-density electromagnetic enhancement hotspots; and simultaneously utilizes the charge transfer induced by the heterogeneous interface formed between the carbon dots and silver nanoparticles to generate chemical enhancement. The synergistic effect of these three enhancement mechanisms achieves cascaded amplification of the Raman signal, significantly improving detection sensitivity.
[0018] 2. The flexible SERS chip of this invention uniformly loads a carbon dot-silver nanoparticle composite onto the three-dimensional fiber network of filter paper using a one-pot in-situ reduction strategy. This eliminates the need for complex surface modification of the filter paper and avoids reliance on expensive equipment such as vacuum sputtering or magnetron sputtering. The fabrication process is simple, convenient, low-cost, and easily scalable. Furthermore, this method retains the original advantages of the filter paper substrate, including its flexibility, portability, environmental friendliness, and natural three-dimensional porous structure, providing a feasible technical path for the commercial application of high-performance flexible SERS substrates.
[0019] 3. The flexible SERS chip of this invention exhibits excellent detection performance. Experimental results show that the chip has a detection limit as low as 10 for Rhodamine 6G (R6G). -15 M, with an enhancement factor as high as ~10 13 Orders of magnitude; excellent signal uniformity on the chip surface, with a relative standard deviation (RSD) of 8.35% and an inter-batch RSD of 4.44%; and can withstand 300 bending cycles without significant signal attenuation, combining ultra-high sensitivity with excellent mechanical flexibility.
[0020] 4. The flexible SERS chip of this invention exhibits excellent stability and repeatability. This invention utilizes carbon dots as a multifunctional integrated medium. The hydroxyl and carboxyl functional groups abundant on the surface of the carbon dots act as stabilizers, effectively improving the dispersion uniformity of silver nanoparticles in the three-dimensional fiber network of filter paper, ensuring the uniformity of the three-dimensional hotspot distribution. Furthermore, they form a protective layer on the surface of the silver nanoparticles, effectively inhibiting the oxidation and aggregation of silver nanoparticles in air, significantly improving the long-term storage stability and lifespan of the chip.
[0021] 5. The flexible SERS chip of this invention is suitable for rapid detection of contaminants in marine food. This chip can directly perform in-situ "swab-detection" sampling on irregular surfaces of aquatic products such as shrimp and fish, making the operation simple and quick. Experiments using crystal violet as the target contaminant show that the chip's detection limit can reach 10. -10 M, and in 10 -4 M to 10 -10 The M concentration exhibits a good linear relationship within a certain range, providing a practical and feasible technical solution for rapid on-site screening of food safety. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0023] Figure 1 The image shows a scanning electron microscope (SEM) image of the carbon dot-silver nanoparticle flexible SERS chip of the present invention, which illustrates the enrichment morphology of nanoparticles on the surface of filter paper fibers. Figure 2 The image shows the energy dispersive spectroscopy (EDS) results of the unmodified filter paper used in this invention, and the percentage content of carbon (C) and oxygen (O) elements. Figure 3 The image shows the energy dispersive spectroscopy (EDS) results of the filter paper modified with carbon dot-silver nanoparticles according to the present invention, and the percentage content of carbon (C), oxygen (O), and silver (Ag) elements. Figure 4 This is a comparison of the elemental analysis results of X-ray photoelectron spectroscopy (XPS) before and after the filter paper used in this invention was modified. Figure 5 This is a fine XPS spectrum analysis of silver after the filter paper was modified for use in this invention. Figure 6 This is a fine XPS spectrum analysis of carbon elements after the filter paper was modified for use in this invention. Figure 7 For 10 -1 Comparison of SERS signal spectra of pure filter paper substrate and carbon dot modified filter paper (CDs FP) substrate when using M Rhodamine 6G as probe; Figure 8 For 10 -6 Comparison of SERS signal spectra of pure filter paper substrate, silver nanoparticle modified filter paper (Ag FP) substrate, carbon dot modified filter paper (CDs FP) substrate, and carbon dot-silver nanoparticle composite modified filter paper (C-Ag NPs FP) substrate when using M Rhodamine 6G as probe; Figure 9 The images show the SERS spectra of the carbon dot-silver nanoparticle flexible SERS chip of this invention under different concentrations of rhodamine 6G solution. Figure 10 This is a graph showing the linear fitting results of the logarithmic values of characteristic peak intensities and the logarithmic values of concentrations in the detection of Rhodamine 6G using the flexible SERS chip of carbon dots-silver nanoparticles of this invention. Figure 11 The image shows the SERS spectrum of different concentrations of crystal violet detected on the surface of shrimp in actual aquatic products using the carbon dot-silver nanoparticle flexible SERS chip of the present invention. Figure 12 The carbon dot-silver nanoparticle flexible SERS chip of this invention is used in crystal violet detection at 1173 cm⁻¹. -1 The graph shows the linear fitting results between the logarithmic values of characteristic peak intensities and the logarithmic values of concentrations. Detailed Implementation
[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0025] I. Fabrication of Flexible SERS Chips Based on Carbon Dot-Silver Nanoparticles This embodiment provides a method for preparing a flexible SERS chip using carbon dot-silver nanoparticles, comprising the following steps: (1) Preparation of carbon dot-silver nanoparticle composite sol At room temperature (25°C) and under continuous magnetic stirring (500 rpm), 5 mL of a 15 mM hexadecylpyridine chloride (CPC) solution and 5 mL of a 45 mM silver nitrate (AgNO3) solution were mixed and stirred for 30 minutes to form a homogeneous silver ion complex system. Subsequently, 2 mL of a 1 M sodium hydroxide (NaOH) solution was slowly added dropwise to this mixture. During the addition, the solution color rapidly changed from milky white to brownish-red, indicating the formation of the carbon dot-silver nanoparticle composite material. The entire synthesis process was carried out under light-protected conditions to prevent photo-aggregation of the silver nanoparticles. After the reaction was complete, a carbon dot-silver nanoparticle composite sol was obtained, denoted as C-Ag NPs sol. Characterization showed that the obtained silver nanoparticles had a particle size of approximately 46 nm.
[0026] (2) Pretreatment of filter paper substrate Qualitative medium-speed filter paper was selected as the flexible substrate material. After being cut to a suitable size, the filter paper was rinsed three times with ultrapure water, followed by ultrasonic cleaning with anhydrous ethanol for 5 minutes to remove organic impurities and contaminants from its surface. After cleaning, the filter paper was dried under a nitrogen stream to obtain a clean surface. The pretreated filter paper was stored in petri dishes for later use.
[0027] (3) Load and curing Freshly prepared C-Ag NPs sol was pipetted onto the pretreated filter paper surface using a micropipette, allowing the sol to fully impregnate the three-dimensional fibrous network structure of the filter paper. The filter paper loaded with C-Ag NPs sol was placed in a petri dish and transferred to a constant-temperature drying oven for static heat treatment at 60°C for 8 hours. During this process, the solvent slowly evaporated, and the carbon dot-silver nanoparticle composite gradually adhered to the surface of the filter paper fibers, forming a uniform and stable nanostructure coating. After heat treatment, the sample was removed and cooled to room temperature in a desiccator, yielding a flexible SERS chip of carbon dot-silver nanoparticles, denoted as C-AgNPs FP. The obtained chip was stored in a dry environment for subsequent characterization and performance testing.
[0028] II. Structural Characterization of Carbon Dot-Silver Nanoparticle Flexible SERS Chip To verify the successful synthesis of the carbon dot-silver nanoparticle composite material and its loading on filter paper, the chip prepared in Example 1 was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS).
[0029] (1) SEM characterization Figure 1 This is a SEM image of nanoparticle enrichment on the carbon dot-silver nanoparticle flexible SERS chip of this invention. From... Figure 1 As can be seen, the surface of the filter paper fibers is completely coated with a dense and uniform layer of nanoparticles, forming abundant nanoscale roughness and high-density narrow gaps between particles. This structure is an ideal site for generating strong localized surface plasmon resonance, providing a large number of "hot spots" for electromagnetic enhancement mechanisms.
[0030] (2) EDS characterization To confirm the presence of carbon dots and their stabilizing effect on silver nanoparticles, EDS energy dispersive spectroscopy analysis was performed on filter paper before and after modification. Figure 2 The image shows the EDS energy dispersive spectroscopy (EDS) results of the unmodified filter paper and its percentage C and O content. From... Figure 2 It can be seen that only C and O elements were detected in the original filter paper, which is consistent with the characteristics of cellulose materials. Figure 3 The image shows the EDS energy dispersive spectroscopy results of the modified filter paper and the percentages of its C, O, and Ag elements. From... Figure 3As can be seen, in addition to C and O, a distinct Ag peak appears, indicating that silver nanoparticles were successfully loaded onto the surface of the filter paper fibers. Meanwhile, with... Figure 2 In contrast, the ratio of C to O elements changed, which is attributed to the alteration of the chemical composition of the fiber surface by the oxygen-containing functional groups abundant in the carbon dots, indirectly proving the existence of carbon dots.
[0031] (3) XPS characterization To further confirm the chemical state of the elements, XPS analysis was performed on the filter paper before and after modification. Figure 4 This is a comparison of XPS elemental analysis results before and after modification of the filter paper used in this invention. Figure 4 It can be seen that the modified sample shows the characteristic peak of Ag 3d, which further confirms the successful loading of silver. Figure 5 This is a fine spectral analysis of Ag after the filter paper was modified for use in this invention. From... Figure 5 It can be seen that the Ag 3d spectrum exhibits typical Ag 3d... 5 / 2 and Ag 3d 3 / 2 The characteristic double peaks prove that silver exists in its elemental form (Ag). 0 )exist. Figure 6 This is a fine spectral analysis of carbon (C) after the filter paper was modified for use in this invention. From... Figure 6 As can be seen, peak fitting reveals carbon in different chemical states, such as CC, COC, and OC=O, clearly indicating that the carbon dots mainly contain sp2 hybridized carbon as well as carboxyl and hydroxyl groups. These hydrophilic functional groups are beneficial for enhancing the dispersibility of the composite material and the adsorption of target molecules.
[0032] III. Performance Testing of Carbon Dot-Silver Nanoparticle Flexible SERS Chip To compare the effects of different modification methods on SERS performance, the following four substrates were prepared: pure filter paper substrate (BlankFP), silver nanoparticle modified filter paper (AgFP), carbon dot modified filter paper (CDsFP), and carbon dot and silver nanoparticle composite modified filter paper (C-AgNPsFP).
[0033] The pure filter paper substrate (Blank FP) is prepared by pretreating the filter paper using the method in step (2) of Example 1.
[0034] The preparation process of AgFP is as follows: Using the silver mirror reaction method, 5 mL of silver nitrate solution (3.0 wt%) and 0.25 mL of sodium hydroxide solution (5.0 wt%) are mixed to generate a brown precipitate. Ammonia water is added dropwise until the precipitate is completely dissolved. Then, 1.5 mL of glucose solution (10.0 wt%) is added as a reducing agent. The pretreated filter paper is immersed in the reaction solution and allowed to stand for 7 minutes. After being removed, it is thoroughly washed with deionized water and ethanol in sequence, and then dried with nitrogen gas to obtain the final product.
[0035] The preparation process of CDs FP is as follows: Carbon dot solution is synthesized using an in-situ reduction method. 5 mL of hexadecylpyridine chloride solution (15 mM) and 1 mL of sodium hydroxide solution (1 M) are mixed at a volume ratio of 5:1 and reacted at room temperature for 2.5-3 hours. After the reaction, the pH is finely adjusted to 5-7 to obtain the carbon dot solution. Pretreated filter paper is then immersed in this solution and transferred to a 60℃ constant temperature drying oven for heat treatment for 8 hours to ensure the carbon dots are firmly loaded onto the filter paper surface. After cooling, it is stored for later use.
[0036] C-Ag NPs FP refers to the chip prepared in Example 1.
[0037] To evaluate the SERS enhancement performance of the fabricated chip, Rhodamine 6G (R6G) was used as a probe molecule for Raman spectroscopy detection.
[0038] Step 1: Preparation of Rhodamine 6G (R6G) series standard solutions. A 0.1 M R6G stock solution was prepared using ultrapure water, followed by stepwise dilution to prepare standard solutions with concentrations ranging from 10 M to 10 M. -2 M to 10 -15 M's R6G series solutions.
[0039] Step 2: Sample addition. Using a pipette, 5 μL of R6G standard solutions of different concentrations are drawn and added to the surface of the prepared C-Ag NP / FP flexible SERS chip, ensuring that the droplets completely cover the detection area of the chip.
[0040] Step 3: Drying and Raman Detection. After adding the sample, the chip was placed in a clean environment and allowed to dry completely at room temperature. The chip was then transferred to the stage of a Raman spectrometer. An excitation wavelength of 532 nm was used, with a laser power of 0.5 mW and an integration time of 1 second. The SERS spectra of the enriched areas on the chip surface were then acquired.
[0041] Step 4: Data Analysis. Record different concentrations of R6G at 614 cm⁻¹. -1 The SERS intensity at the characteristic peak was used to plot a calibration curve with the logarithm of intensity and the logarithm of concentration. The regression equation and correlation coefficient were obtained through linear fitting.
[0042] (1) Verification of the reinforcing effect of carbon dots To verify the reinforcing effect of carbon dots, 10 -1 Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS signals of pure filter paper substrates and carbon dot-modified filter paper (CDs FP) substrates. Figure 7 The carbon dot-silver nanoparticle flexible SERS chip of this invention uses 10 -1 MR6G is used as a probe; signal spectra of two different substrates. From Figure 7 It can be seen that at higher concentrations, the CDs FP substrate exhibits a better reinforcing effect than the pure filter paper substrate, verifying the reinforcing effect of carbon dots.
[0043] (2) Comparison of SERS performance on different substrates With 10 -1 MR6G is a probe molecule used to compare the SERS signals of the four substrates mentioned above. Figure 8 The carbon dot-silver nanoparticle flexible SERS chip of this invention uses 10 -1 MR6G is used as a probe; signal spectra of four different substrates. From Figure 8 It can be seen that in 10 -6 At M concentration, pure filter paper and carbon dot-modified filter paper substrates showed almost no Raman signal; silver nanoparticle-modified filter paper substrates exhibited certain Raman characteristic peaks, indicating that they possess electromagnetic enhancement capabilities; while the signal intensity of carbon dot-silver nanoparticle composite-modified filter paper substrates was significantly higher than the other three, proving that the composite structure of carbon dots and silver nanoparticles can synergistically enhance SERS performance.
[0044] (3) Sensitivity and uniformity test The spectral results of using a flexible SERS chip with carbon dots and silver nanoparticles for Raman detection are as follows: Figure 9 As shown. From Figure 9 As can be seen from this, as the R6G concentration increases from 10... -9 M drops to 10 -15 M, its 614 cm -1 The SERS characteristic peak signal at that location remains clearly discernible, demonstrating extremely high signal amplification capability, with a detection limit as low as 10. -15 M.
[0045] Carbon dot-silver nanoparticle flexible SERS chip in different concentrations of R6G 614 cm -1 The linear fitting results of the logarithmic values of intensity and concentration are as follows: Figure 10 As shown. From Figure 10 As can be seen, the logarithm of peak intensity has an excellent linear relationship with the logarithm of concentration (R0). 2 =0.994), indicating that the method has the ability of semi-quantitative analysis.
[0046] Signals were collected from 100 randomly selected points on the chip surface. The relative standard deviation (RSD) of the characteristic peak intensity was calculated to be 8.35%, and the batch-to-batch RSD was 4.44%, indicating that the chip has excellent signal uniformity and fabrication repeatability.
[0047] IV. Application of Carbon Dot-Silver Nanoparticle Flexible SERS Chips in Real Samples (1) Preparation of simulated contamination samples Healthy, fresh shrimp were soaked in different concentrations (10... -4 M, 10 -5 M, 10 -6 M, 10 -7 M, 10 -8 M, 10 -9 M, 10 -10 Shrimp were immersed in a crystal violet (CV) standard solution (M) for 12 hours to simulate potential illegal drug residue contamination during farming, transportation, or sales. After immersion, the shrimp were removed, gently patted dry with filter paper, and set aside. A control group of untreated shrimp was also included.
[0048] (2) In-situ swabbing sampling After fixing the treated shrimp samples, the C-Ag NPs flexible SERS chip prepared in Example 1 was used to directly swab the surface of the shrimp shells for sampling. During sampling, the chip was held with clean tweezers, and the same area on the shrimp shell surface was swabled back and forth three times with constant pressure. The total contact time was maintained at 15 seconds to ensure that the analyte molecules were fully adsorbed and transferred to the chip surface. The blank control group was sampled by swabbing in the same way.
[0049] (3) Drying and Raman detection After sampling, the chip was placed in a clean environment and allowed to dry naturally at room temperature for 1-2 minutes until completely dry. The chip was then transferred to the stage of a Raman spectrometer, and an excitation wavelength of 633 nm was used. A 50× telephoto objective lens was used, the laser power was set to 0.17 mW, and the integration time was 10 seconds to collect the SERS spectrum of the enriched area on the chip surface.
[0050] (4) Test results Figure 11 This is a SERS spectrum of different concentrations of crystal violet detected on the surface of shrimp in actual aquatic products using the carbon dot-silver nanoparticle flexible SERS chip of this invention. Figure 11 As can be seen, the substrate successfully detected levels as low as 10 on the spiked shrimp shell surface. -10 The CV of M is located at 1173 cm. -1 The characteristic peak signal is significant.
[0051] Figure 12 This is a graph showing the linear fitting results of the intensity logarithm of the carbon dot-silver nanoparticle flexible SERS chip of the present invention with the concentration logarithm of crystal violet at different concentrations. From... Figure 12 It can be seen that in 10 -4 M to 10 -10 Within the M concentration range, 1173 cm -1 The peak intensity logarithm showed a good linear relationship with the concentration logarithm, verifying the potential of this chip for quantitative analysis in actual sample detection.
[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for fabricating a flexible SERS chip, characterized in that, Includes the following steps: S1. Preparation of carbon dot-silver nanoparticle composite sol: Under stirring conditions, hexadecylpyridine chloride solution and silver nitrate solution are mixed to form a silver ion complex system; then sodium hydroxide solution is added dropwise to the silver ion complex system to react and obtain carbon dot-silver nanoparticle composite sol. S2. Filter paper substrate pretreatment: Cleaning and drying the filter paper; S3. Loading and curing: The carbon dot-silver nanoparticle composite sol prepared in step S1 is loaded onto the surface of the filter paper after pretreatment in step S2, and then dried and cured to form a carbon dot-silver nanoparticle composite coating on the surface of the three-dimensional fiber network of the filter paper, thus obtaining a flexible SERS chip.
2. The preparation method according to claim 1, characterized in that, In step S1, the concentration of the hexadecylpyridine chloride solution is 10-20 mM, the concentration of the silver nitrate solution is 40-50 mM, and the concentration of the sodium hydroxide solution is 0.8-1.2 M.
3. The preparation method according to claim 1, characterized in that, In step S1, the volume ratio of the hexadecylpyridine chloride solution, silver nitrate solution and sodium hydroxide solution is (4-6):(4-6):(1-3).
4. The preparation method according to claim 1, characterized in that, In step S1, the reaction is carried out under light-protected conditions; the stirring rate is 400-600 rpm, and the stirring time is 20-40 minutes.
5. The preparation method according to claim 1, characterized in that, In step S2, the cleaning is performed by sequentially rinsing with ultrapure water and ultrasonically cleaning with anhydrous ethanol; the drying is performed by drying with nitrogen gas flow.
6. The preparation method according to claim 1, characterized in that, In step S3, the loading method is to drop the carbon dot-silver nanoparticle composite sol onto the surface of the filter paper or to immerse it in the carbon dot-silver nanoparticle composite sol.
7. The preparation method according to claim 1, characterized in that, In step S3, the drying and curing process is a heat treatment at 50-70°C for 6-10 hours.
8. A flexible SERS chip prepared by the preparation method according to any one of claims 1-8.
9. The application of a flexible SERS chip prepared by the method according to any one of claims 1-13 in the detection of contaminants in marine food.
10. The application according to claim 9, characterized in that, The application involves in-situ wiping and sampling to detect contaminants on the surface of marine food products.