Incubation-free composite SERS substrate as well as preparation method and application thereof

Abstract

The invention provides an incubation-free composite SERS (Surface Enhanced Raman Scattering) substrate as well as a preparation method and application thereof. The preparation method comprises the following steps: providing Ag nanoparticles; providing a nano carbon material, and loading the Ag nanoparticles on the surface of the nano carbon material to form an SERS solution system with a composite nano structure; loading a cationic polyelectrolyte structure on the surface of the nanofiber membrane to obtain a composite fiber membrane; the SERS solution system is dripped onto the composite fiber membrane, and the incubation-free composite SERS substrate is obtained. The detection efficiency and sensitivity of the sulfonamide antibiotics can be remarkably improved, and the application prospect is wide.

Description

Technical Field

[0001] This application relates to the field of spectral analysis, specifically to an incubation-free composite SERS substrate, its preparation method, and its application. Background Technology

[0002] Sulfasalazine (SSZ) is a synthetic antibiotic widely used to treat inflammatory diseases such as ulcerative colitis and rheumatoid arthritis. However, overuse of SSZ can lead to various side effects, including allergic reactions, hematopoietic disorders, and potential carcinogenic risks. In environmental water bodies, the typical concentration range of SSZ and its metabolites is between 2.51 pM and 2.51 nM. When SSZ enters aquatic ecosystems, it can damage proteins, nucleic acids, and other cellular components in aquatic organisms. Furthermore, antibiotic pollution and its associated ecological risks (such as the proliferation of drug-resistant bacteria) have significant time lags, and their toxicity increases over time, complicating environmental risk assessment and pollution source identification. Conventional detection methods are insufficient for rapid determination at such ultra-low concentrations; therefore, the development of highly sensitive and rapid environmental monitoring and risk assessment technologies for SSZ detection is urgently needed.

[0003] Currently, traditional methods for determining SSZ and its metabolites mainly include liquid chromatography-tandem mass spectrometry (LC-MS). While these techniques possess excellent separation capabilities, they have long analysis times (usually exceeding 10 minutes) and require complex sample pretreatment, making them unsuitable for rapid on-site detection. Rapid detection methods such as electrochemical and fluorescence spectroscopy have gained attention due to their ease of operation and rapid response; however, they each have significant limitations: electrochemical methods are susceptible to electrode surface contamination and difficult cleaning, leading to large fluctuations in sensitivity and poor reproducibility; fluorescence spectroscopy is affected by background fluorescence and light scattering interference, severely impacting detection accuracy. These shortcomings in sensitivity and speed highlight the need for novel analytical techniques that combine high sensitivity with rapid on-site detection capabilities.

[0004] Surface-enhanced Raman scattering (SERS) technology is considered an ideal platform for breakthroughs due to its combination of ultra-high sensitivity, non-destructive nature, and rapid analytical capabilities. In recent years, SERS has demonstrated great potential in the detection of antibiotic residues. However, its application to the detection of sulfonamide antibiotics (such as SSZ) still faces several major challenges: First, these molecules have weak affinity for noble metal surfaces and small Raman scattering cross-sections, resulting in limited detection sensitivity, with detection limits typically in the μM to nM range; second, existing SERS methods often require long incubation periods to enrich target molecules, making it difficult to achieve highly sensitive real-time detection of antibiotic contaminants. Furthermore, while SERS technology shows great promise, its application in the efficient and reliable detection of SSZ remains an unexplored area. There is an urgent need to develop a highly sensitive SERS substrate that can achieve SSZ measurements without pretreatment or incubation, for the rapid enrichment and detection of antibiotic contaminants in complex environmental systems.

[0005] A search revealed that patent application CN119327281A discloses a method for preparing an enrichment-enhanced bifunctional filter membrane SERS substrate, comprising: preparing Ag nanoparticles and functionalizing them; self-assembling the functionalized Ag nanoparticles with nano-carbon materials, loading them onto the surface of the nano-carbon materials to form a hybrid structure; anchoring the hybrid structure using a matrix with a fibrous structure to obtain a composite nanostructured SERS solution system; and filtering the SERS solution system onto a glass fiber filter membrane to form an enrichment-enhanced bifunctional filter membrane SERS substrate. The "hot spots" of this technology depend on the random stacking of the Ag / nano-carbon hybrid structure during the filtration process, which is an uncontrollable physical process. The distribution, density, and enhancement strength of the resulting "hot spots" are highly random, leading to poor uniformity of SERS signals (typically high RSD) across different batches and even different locations on the same substrate.

[0006] Patent application CN114891349A discloses a process of mixing ReS2 material with dopamine to obtain a ReS2 material with a polydopamine coating; then, mixing the polydopamine-coated ReS2 material with cationic polyelectrolytes and noble metal nanoparticles to prepare a composite exhibiting the SERS effect; finally, concentrating and loading the SERS-effect composite onto a substrate surface to obtain a SERS substrate. This technology involves a complex process, including the synthesis of ReS2, polydopamine coating, and mixing with polyelectrolytes / noble metals, presenting significant challenges in reproducibility, high costs, and difficulty in large-scale production. Summary of the Invention

[0007] In view of one of the defects in the prior art, the purpose of this application is to provide an incubation-free composite SERS substrate, its preparation method and application.

[0008] According to a first aspect of this application, a method for preparing an incubation-free composite SERS substrate is provided, comprising: Provides Ag nanoparticles; A nano-carbon material is provided, and Ag nanoparticles are loaded onto the surface of the nano-carbon material to form a SERS solution system with a composite nanostructure. A composite fiber membrane is obtained by loading a cationic polyelectrolyte structure onto the surface of a nanofiber membrane. The SERS solution system is dropped onto the composite fiber membrane to obtain an incubation-free composite SERS substrate.

[0009] Optionally, the provision of Ag nanoparticles includes: A mixed solution of hydroxylamine hydrochloride and sodium hydroxide is provided, and an aqueous solution of silver nitrate is added dropwise to the mixed solution; After stirring, a yellowish-gray silver colloid is obtained, which is Ag nanoparticles.

[0010] Optionally, the provision of nano-carbon materials includes any one of graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes.

[0011] Optionally, the cationic polyelectrolyte structure is loaded onto the surface of the nanofiber membrane to obtain a composite fiber membrane, wherein the cationic polyelectrolyte is any one of polydiallyldimethylammonium chloride, polyethyleneimine, and polyallylamine hydrochloride.

[0012] Optionally, the step of dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate includes: dropping the SERS solution system of the composite nanostructure onto the composite fiber membrane using a pipette.

[0013] Optionally, the pore size of the composite fiber membrane is smaller than the minimum size of the composite nanostructure.

[0014] Optionally, after dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate, the method includes: vacuum sealing and storing the composite SERS substrate.

[0015] According to a second aspect of this application, an incubation-free composite SERS substrate is provided, which is prepared using the method described above.

[0016] According to a third aspect of this application, an application is provided for using an incubation-free composite SERS substrate prepared by the method described in the first aspect or an incubation-free composite SERS substrate described in the second aspect, wherein the composite SERS substrate is used to detect sulfonamide antibiotics in an aquatic environment.

[0017] Optionally, the application includes: Provide the water sample to be tested; Take a water sample to be tested and drop it onto the surface of the composite SERS substrate; Raman spectroscopy was directly performed on water samples from the surface of the composite SERS substrate to achieve rapid detection of sulfonamide antibiotics in the water samples.

[0018] The method for preparing an incubation-free composite SERS substrate provided in this application involves dropping a composite nanostructured SERS solution system onto a cationic polyelectrolyte-loaded nanofiber membrane, enabling the substrate to rapidly assemble samples and amplify signals. For water samples to be tested, no complex pretreatment or incubation is required; efficient and rapid detection can be achieved simply by dropping the solution, thereby significantly improving the efficiency and sensitivity of Raman detection of sulfonamide antibiotics.

[0019] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart illustrating a method for preparing an incubation-free composite SERS substrate according to an exemplary embodiment; Figure 2 This is a schematic diagram illustrating the preparation and detection method of a GF@PDDA-Ag / rGO composite SERS substrate according to an exemplary embodiment; Figure 3 The following are SEM characterization results of different materials according to an exemplary embodiment, wherein: (a) is a statistical diagram of Ag nanoparticles and their particle size distribution, and a scanning electron microscope image of the GF@PDDA-Ag / rGO composite substrate, with magnifications of: (b) 1.50kx, (c) 10.0kx and (d) 200kx, respectively; Figure 4 To detect Raman spectra of SSZ at different concentration gradients using a highly sensitive, incubation-free composite SERS substrate according to an exemplary embodiment. Detailed Implementation

[0021] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0022] In the efficient and reliable detection of antibiotic contaminants such as SSZ in complex environmental systems, current SERS substrates suffer from limited detection sensitivity and difficulty in achieving highly sensitive real-time detection of antibiotic contaminants. To address these issues, this application provides a method for preparing an incubation-free composite SERS substrate to solve these problems.

[0023] Reference Figure 1 and Figure 2 In one embodiment of this application, a method for preparing an incubation-free composite SERS substrate includes the following steps: S1, provides Ag nanoparticles; S2. Provide nano-carbon materials, load Ag nanoparticles onto the surface of nano-carbon materials to form a composite nanostructured SERS solution system; S3. Load the cationic polyelectrolyte structure onto the surface of the nanofiber membrane to obtain a composite fiber membrane; S4. Drop the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate.

[0024] Specifically, to achieve rapid and highly sensitive detection of sulfonamide antibiotic pollutants such as SSZ in aquatic environments, Ag nanoparticles are first prepared. These Ag nanoparticles are then self-assembled with carbon nanomaterials, allowing the Ag nanoparticles to be loaded onto the surface of the carbon nanomaterials, forming a composite nanostructured SERS solution system. A cationic polyelectrolyte structure is pre-loaded onto the surface of a nanofiber membrane for further loading of the composite nanoparticles. The composite nanostructured SERS solution system is then gently dropped onto the nanofiber membrane to obtain a highly sensitive, incubation-free composite SERS substrate. For the water sample to be tested, no complex pretreatment or incubation is required; efficient and rapid detection can be achieved simply by dropping the substrate, significantly improving the sensitivity and efficiency of the detection. This solves the technical problem of lacking a more sensitive and faster antibiotic detection substrate in existing technologies and has broad application prospects.

[0025] In order to synthesize Ag nanoparticles as a metal plasma to enhance the Raman signal of the target molecule, in some specific embodiments of this application, S1, providing Ag nanoparticles may include the following steps: S11. Provide a mixed solution of hydroxylamine hydrochloride and sodium hydroxide, and add silver nitrate aqueous solution dropwise to the mixed solution; S12. After stirring, a yellowish-gray silver colloid is obtained, which is Ag nanoparticles.

[0026] For example, 10 mL of silver nitrate aqueous solution (10 mL, 10 -2 M) was added dropwise to hydroxylamine hydrochloride (90 mL, 1.67 × 10⁻⁶). -3The mixture of 1 M and sodium hydroxide (300 μL, 1 M) was stirred magnetically for 30 min to obtain a yellowish-gray silver colloid, which is Ag nanoparticles (Ag nanoparticle sol).

[0027] In some specific embodiments of this application, in step S2, the nano-carbon material is any one of graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes.

[0028] Specifically, in step S2, the carbon nanomaterial used has a high specific surface area, which provides sufficient sites for the attachment of metal nanoparticles and effectively inhibits the aggregation of silver nanoparticles due to their high surface energy, allowing them to disperse as single particles or micro-clusters on the two-dimensional plane of reduced graphene oxide. This structure not only maximizes the exposure of the active surface of the silver nanoparticles, ensuring a strong electromagnetic enhancement effect, but also, due to the close physical contact formed between the silver nanoparticles and the highly conductive reduced graphene oxide, greatly promotes the rapid transfer of hot electrons generated under photoexcitation at the interface between the two, thereby significantly enhancing the contribution of chemical enhancement.

[0029] For example, Ag nanoparticles are loaded onto the surface of carbon nanomaterials to form a SERS solution system with a composite nanostructure. The specific process is as follows: 0.1 mg of rGO powder is placed in 1 mL of deionized water and ultrasonically dispersed for 5 minutes. Then, an appropriate amount of rGO dispersion (50-800 μL) is mixed with 1 mL of AgNPs and stirred for 1 hour to prepare an Ag / rGO composite material for later use.

[0030] By combining silver nanoparticles with carbon nanomaterials using the aforementioned self-assembly method, the silver nanoparticles can be uniformly distributed on the surface of the carbon nanomaterials, effectively combining electromagnetic and chemical enhancement to achieve synergistic effects. Furthermore, thanks to the unique π-π stacking effect of carbon nanomaterials, they can selectively adsorb analyte molecules containing aromatic rings, further enhancing the detection sensitivity and recognition selectivity of the SERS substrate.

[0031] It is important to note that the SERS signal intensity of Ag nanoparticles primarily depends on the localized surface plasmon resonance (LSPR) they induce. Particle size mainly modulates the position of the LSPR peak. The strongest signal enhancement is only achieved when the LSPR peak is well matched with the incident laser wavelength and Raman scattering peak. Particles that are too large or too small will lead to mismatch and reduced efficiency. Particle morphology determines the spatial distribution of the electromagnetic field. Structures with sharp tips, edges, or small gaps (such as star-shaped, cubic, or closely spaced particles) can greatly localize the light field, forming "hot spots" and producing an enhancement effect far exceeding that of smooth surfaces (typically several orders of magnitude higher). High SERS signals arise from the synergy of optimal size (ensuring light absorption / scattering efficiency matches the wavelength) and complex morphology (providing dense, high-intensity hot spots). An ideal SERS substrate needs to strike a balance between these two factors to achieve a highly sensitive and reproducible signal.

[0032] In order to load cationic polyelectrolytes onto the surface of nanofiber membranes to form a modified matrix for further guiding and loading composite nanoparticles, in some specific embodiments of this application, S3, the cationic polyelectrolyte structure is loaded onto the surface of the nanofiber membrane to obtain a composite fiber membrane, wherein: the cationic polyelectrolyte is any one of polydiallyldimethylammonium chloride, polyethyleneimine, and polyallylamine hydrochloride.

[0033] Specifically, the aforementioned cationic polyelectrolyte can dissociate in aqueous solution to form polymer chains with a high density of positive charges. When modified onto the surface of a negatively charged nanofiber membrane, it can form a stable positively charged modification layer through electrostatic adsorption. This polyelectrolyte layer can efficiently and directionally capture and fix negatively charged metal nanoparticles and nano-carbon material composites on their surfaces through strong electrostatic attraction, thereby guiding the composite nanoparticles to undergo high-density, uniform, and ordered self-assembly on the fiber surface. This process helps to precisely control the gaps between nanoparticles, constructing a uniformly distributed array of high-intensity electromagnetic "hot spots," laying the foundation for obtaining a stable and uniform SERS signal.

[0034] Furthermore, this cationic polyelectrolyte layer not only serves as an assembly interface, but its strong positive charge also allows for effective regulation of the charge environment within the detection system. For example, it can influence the adsorption behavior and enrichment efficiency of analyte molecules with specific charges on the substrate surface through electrostatic interactions or charge shielding effects, thereby further enhancing the sensitivity and adaptability of SERS detection.

[0035] For example, the nanofiber membrane is a glass fiber membrane.

[0036] In some specific embodiments of this application, S4, dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate, includes: dropping the SERS solution system of the composite nanostructure onto the composite fiber membrane using a pipette.

[0037] In some specific embodiments of this application, the pore size of the composite fiber membrane is smaller than the minimum size of the composite nanostructure.

[0038] In some specific embodiments of this application, after dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate, the method includes: vacuum sealing and storing the composite SERS substrate.

[0039] In step S4, the SERS solution system of the composite nanostructure is gently dropped onto the composite fiber membrane. The pore size of the composite fiber membrane is determined according to the size of the composite nanostructure and should be smaller than the minimum size of the composite nanostructure. It is generally recommended that the selected membrane pore size be 20%-30% smaller than the minimum diameter of the composite nanostructure to ensure that the composite nanostructure can be effectively retained and aggregated during the droplet process. The obtained composite SERS substrate is then vacuum sealed and stored.

[0040] The embodiments described above in this application hybridize Ag nanoparticles with nano-carbon materials having a large specific surface area, allowing the Ag nanoparticles to be loaded onto the surface of the nano-carbon material. This indirectly modulates the interparticle spacing of the metal nanoparticles, constructing a high-density SERS hotspot. Simultaneously, a cationic polyelectrolyte-modified matrix is ​​used beforehand, i.e., it is loaded onto a nanofiber membrane. Then, the hybrid structure is gently dropped onto the surface of the fiber membrane, allowing it to be firmly anchored within the fiber framework, enhancing the stability and signal uniformity of the substrate, resulting in a highly sensitive, incubation-free composite SERS substrate. This integrated composite SERS substrate requires no complex sample pretreatment steps and no incubation; efficient and rapid detection of antibiotics such as SSZ in water can be achieved simply by dropping the substrate. The entire detection process exhibits high sensitivity and accuracy, making it suitable for the rapid detection of antibiotic pollutants in aquatic environments.

[0041] Compared to the prior art CN119327281A, in the embodiments of this application, the cationic polyelectrolyte (such as polydiallyldimethylammonium chloride) molecular chains form a uniform positively charged layer on the fiber surface, which can serve as a nanoscale electrostatic template to precisely guide the directional aggregation of negatively charged Ag / rGO, thereby actively constructing a more uniform high-density "hot spot" array. The prior art CN114891349A does not emphasize the selective enrichment function for specific analytes. In comparison, the process of this application is simple, efficient, and reproducible. More importantly, the embodiments of this application utilize the electrostatic bridging effect of the polyelectrolyte to achieve a stable integration of the functional matrix (fiber membrane) and the reinforcing unit (Ag / rGO) in one step.

[0042] Another embodiment of this application provides an incubation-free composite SERS substrate, which is prepared using the method described in any of the above embodiments. This filter membrane SERS substrate can be used to directly measure antibiotic pollutants in the aquatic environment, achieving efficient sample enrichment and Raman signal enhancement, thereby enabling rapid detection of antibiotic pollutants such as SSZ in the aquatic environment.

[0043] Another embodiment of this application provides an application of the above-mentioned incubation-free composite SERS substrate, which is used to detect sulfasalazine and other sulfonamide antibiotics in an aquatic environment.

[0044] In some specific embodiments of this application, the application method includes: M1. Provide the water sample to be tested; M2. Take out the composite SERS substrate, use a pipette to transfer the water sample to be tested, and gently drop it onto the surface of the composite SERS substrate. M3 allows for direct Raman spectroscopy acquisition of water samples on the surface of a composite SERS substrate without additional incubation time, enabling rapid detection of sulfonamide antibiotics in water samples.

[0045] In the embodiments described above, Ag nanoparticles are loaded onto the surface of nano-carbon materials to construct a composite structure, resulting in a composite nanostructured SERS solution system. Simultaneously, a cationic polyelectrolyte is pre-loaded onto the surface of a nanofiber membrane, and then the SERS solution system is dropped onto the fiber membrane. This enables the membrane to rapidly assemble samples and amplify signals, significantly improving the efficiency and sensitivity of sample analysis. For water samples containing antibiotics (such as SSZ), no complex pretreatment or incubation is required; efficient and rapid detection can be achieved simply by adding the solution. The embodiments described above overcome the problems of complex and time-consuming water sample pretreatment, low detection sensitivity, and poor SERS substrate stability in existing technologies. The detection method provided in these embodiments requires no complex pretreatment or incubation, and combined with a portable Raman spectrometer, it achieves efficient and rapid detection simply by adding the solution, facilitating the development of on-site rapid SERS detection applications.

[0046] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0047] The following examples and comparative examples further illustrate this application to better understand the above-mentioned technical solutions. It should be understood that these are merely examples and are not intended to limit the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through commercial channels.

[0048] The highly sensitive, incubation-free composite SERS substrate provided in this embodiment is specifically a glass fiber membrane@polydiallyldimethylammonium chloride-silver nanoparticles / reduced graphene oxide (GF@PDDA-Ag / rGO) composite SERS substrate, as described above. Figure 1 and Figure 2 Its preparation method includes the following steps: Step 1: Synthesize Ag nanoparticle sol.

[0049] Add silver nitrate aqueous solution (10 mL, 10) -2 M) was added dropwise to hydroxylamine hydrochloride (90 mL, 1.67 × 10⁻⁶). -3 The mixture was prepared with a solution of sodium hydroxide (300 μL, 1 M) and sodium hydroxide (300 μL, 1 M). After magnetic stirring for 30 min, a yellowish-gray Ag colloid was obtained.

[0050] The particle size and size distribution of silver nanoparticles (AgNPs) were characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS). TEM images ( Figure 3 a) The AgNPs exhibit a regular morphology with an average particle size of approximately 64.5 ± 0.807 nm, confirming their hydrodynamic diameter and dispersion stability.

[0051] In other embodiments, the size of the Ag nanoparticles can be optimized to enhance the SERS signal intensity.

[0052] Step 2: Self-assembly of Ag and rGO.

[0053] Take 0.1 mg rGO powder and place it in 1 mL of deionized water, then disperse it by ultrasonication for 5 minutes. Subsequently, mix an appropriate amount of rGO dispersion (50-800 uL) with 1 mL of AgNPs and stir for 1 h to prepare Ag / rGO composite material for later use.

[0054] SEM images ( Figure 3 (b) The three-dimensional network structure formed by interwoven glass fibers is clearly presented, with layered reduced graphene oxide (rGO) embedded in the pores, further verifying its hydrodynamic diameter and dispersion stability. High-magnification SEM image ( Figure 3c) shows that, due to the premixing of AgNPs and rGO before composite formation, some AgNPs are uniformly anchored on the surface of rGO nanosheets, forming a stable Ag / rGO composite structure. This structure not only inhibits AgNP aggregation but also significantly increases the specific surface area due to the abundant loading sites provided by the wrinkled morphology of rGO.

[0055] Step 3: Loading of PDDA and glass fiber membrane.

[0056] Dissolve polydiallyl ammonium chloride (PDDA) in deionized water (concentration 0.001%-0.5%), take 5 μL of the solution and drop it onto the glass fiber membrane, dry at 60 ℃ and then cool.

[0057] Step 4: Preparation and characterization of the GF@PDDA-Ag / rGO composite substrate.

[0058] A 0.1 μm glass fiber membrane was used as the matrix. The 5 μL SERS solution system of the Ag / rGO composite nanostructure prepared in step 2 was gently dropped onto the glass fiber membrane (0.1 μm, 25 mm). High-magnification SEM image (…). Figure 3 d) shows that, due to the bridging effect of PDDA, negatively charged AgNPs are uniformly anchored on the surface of the glass fiber membrane, forming a stable and dense hot spot region. The GF@PDDA-Ag / rGO composite SERS substrate was finally prepared and stored in a vacuum-sealed bag.

[0059] Continue to refer to Figure 2 The highly sensitive, incubation-free composite SERS substrate was used to measure sulfasalazine, a typical antibiotic pollutant in the aquatic environment. The specific procedure is as follows: Take 1 mL of simulated water sample, filter it once, and then take out the filter membrane for Raman spectroscopy. Figure 4 Different concentrations (10) were shown. -7 Up to 10 -11 The average SERS spectrum of SSZ at concentrations as low as 10 mol / L. It is noteworthy that even at concentrations as low as 10 mol / L... -10 At mol / L, the characteristic peaks of SSZ remained clearly discernible. This indicates that the GF@PDDA-Ag / rGO composite SERS substrate has great potential for detecting antibiotic contaminants. This method shows promise for rapid detection and early risk warning in aquatic and soil environments of key polluted areas such as pharmaceutical wastewater.

[0060] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method for preparing an incubation-free composite SERS substrate, characterized in that, include: Provides Ag nanoparticles; A nano-carbon material is provided, and Ag nanoparticles are loaded onto the surface of the nano-carbon material to form a SERS solution system with a composite nanostructure. A composite fiber membrane is obtained by loading a cationic polyelectrolyte structure onto the surface of a nanofiber membrane. The SERS solution system is dropped onto the composite fiber membrane to obtain an incubation-free composite SERS substrate.

2. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, The provision of Ag nanoparticles includes: A mixed solution of hydroxylamine hydrochloride and sodium hydroxide is provided, and an aqueous solution of silver nitrate is added dropwise to the mixed solution; After stirring, a yellowish-gray silver colloid is obtained, which is Ag nanoparticles.

3. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, The provided nano-carbon material is any one of graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes.

4. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, The process involves loading a cationic polyelectrolyte structure onto the surface of a nanofiber membrane to obtain a composite fiber membrane, wherein the cationic polyelectrolyte is any one of polydiallyldimethylammonium chloride, polyethyleneimine, and polyallylamine hydrochloride.

5. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, The step of dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate includes: dropping the SERS solution system of the composite nanostructure onto the composite fiber membrane using a pipette.

6. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, The pore size of the composite fiber membrane is smaller than the minimum size of the composite nanostructure.

7. The method for preparing the incubation-free composite SERS substrate according to claim 1, characterized in that, After dropping the SERS solution system onto the composite fiber membrane to obtain an incubation-free composite SERS substrate, the process includes: vacuum sealing and storing the composite SERS substrate.

8. A no-incubation composite SERS substrate, characterized in that, It is prepared using the method described in any one of claims 1-7.

9. An application of an incubation-free composite SERS substrate prepared by the method of any one of claims 1-7 or the incubation-free composite SERS substrate of claim 8, characterized in that, The composite SERS substrate was used to detect sulfonamide antibiotics in aquatic environments.

10. The application according to claim 9, characterized in that, include: Provide the water sample to be tested; Take a water sample to be tested and drop it onto the surface of the composite SERS substrate; Raman spectroscopy was directly performed on water samples from the surface of the composite SERS substrate to achieve rapid detection of sulfonamide antibiotics in the water samples.

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