Self-cleaning flexible SERS (Surface Enhanced Raman Scattering) blotting membrane for selectively detecting trace microcystin

Abstract

The invention provides a preparation method and application of a high-sensitivity imprinted membrane for selectively detecting microcystic toxins (MC-LR) in water based on surface enhanced Raman scattering. The preparation method comprises the following steps: step 1, preparation of silver nanocubes; step 2, preparation of Ag NCs-coated TiO2 nanoparticles; step 3, preparation of an Ag NCs-coated TiO2 / PDMS composite membrane; according to the invention, a membrane technology, an SERS technology and MIT are combined, so that the prepared product has excellent physical and chemical properties of a PDMS membrane, high sensitivity of an SERS detection technology and high selectivity of MIT; the invention provides a new method for SERS detection and widens the application range.

Description

TECHNICAL FIELD

[0001] The present application relates to a flexible SERS imprinting film material with self-cleaning performance for selective detection of trace microcystin, belonging to the technical field of new materials. BACKGROUND

[0002] In recent years, due to the adverse effects of modern industry, agriculture and living activities on aquatic ecosystems, the frequency of algal bloom events continues to rise. Microcystin-LR (MC-LR), as a class of toxic cyclic heptapeptide cyanotoxins, is released by decaying algae in algal blooms, and its strong hepatotoxicity can pose a significant threat to human health. According to the requirements of the World Health Organization (WHO) and the relevant international agreements of the Chinese government, the maximum allowable concentration of MC-LR in drinking water shall not exceed . At present, the analysis techniques commonly used for microcystin detection mainly include high-performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry, immunoassay and a variety of other sensing technologies. Although these methods have excellent detection performance, there are still several limitations that need to be optimized, including dependence on expensive and complex instruments, need for professionally trained operators, and lengthy sample pretreatment procedures. Therefore, there is an urgent need for an efficient and highly sensitive analysis method that can accurately identify and quantitatively analyze trace MC-LR in drinking water samples.

[0003] Surface-enhanced Raman scattering (SERS) is an outstanding label-free spectroscopic method for molecular analysis. By utilizing the localized surface plasmon resonance (LSPR) effect on nanostructured metal substrates, SERS can achieve the detection of trace concentrations of analytes while preserving their characteristic vibrational fingerprints. This enhancement property is mainly attributed to the enhanced electromagnetic field (EM) generated by the LSPR of plasmonic nanostructures (e.g., gold (Au) and silver (Ag) nanostructures), which can significantly amplify the Raman signal in the 'hot spot' region. In addition, it is worth emphasizing that the detection performance of SERS largely depends on the preparation and optimization of the active substrate. To date, techniques such as chemical synthesis, self-assembly, and nanolithography have been used to prepare solid-state SERS substrates. However, the application of flexible substrates has become a new trend, which has significant advantages such as good mechanical flexibility, light weight, and conformal contact with irregular or soft surfaces. These characteristics not only expand the application scenarios of SERS in real environments but also help improve the reproducibility and acquisition efficiency of signals. Materials such as polydimethylsiloxane (PDMS) films have been widely explored as flexible SERS platforms due to their low cost, ease of preparation, and suitability for large-area production. To further enhance the sensitivity, specificity, and accuracy of SERS detection, semiconductor SERS active substrates developed in recent years exhibit unique advantages such as low cost, recyclability, high structural and chemical stability, strong selectivity, and good biocompatibility, making them considered as promising SERS substrate candidates. These substrates can achieve precise control of metal nanostructures and good reproducibility, thereby ensuring stable amplification of Raman signals.

[0004] However, there are many interference factors in the actual environmental detection process: SERS technology lacks specific recognition ability for analytes, and the rapid identification and enrichment of target substances in complex samples are still a major challenge. Therefore, SERS needs to be combined with technologies that have specific recognition functions for target substances to achieve accurate detection of analytes in real environmental samples. However, the existing composite methods have limited adaptability in field applications, and they rely on the physical and chemical properties of the analytes for targeted binding rather than enhancing the detection performance of the sensing mechanism itself, so there is an urgent need to enhance the practicality of such technologies for on-site monitoring. To further improve the detection accuracy and sensitivity of microcystin-LR (MC-LR), we introduced the molecular imprinting technique (MIT) combined with SERS detection to significantly optimize the detection performance. The molecularly imprinted polymer (MIPs) coated on the film surface can effectively protect the SERS substrate from air oxidation. However, the traditional thermal polymerization process can damage the molecular structure of MC-LR, so we introduced a photo-induced polymerization technique to achieve selective detection. This technique initiates the polymerization reaction by light irradiation, not only with fast polymerization rate, but also can avoid the inherent defects of traditional thermal polymerization process, thereby effectively improving the specific selection ability for target substances. SUMMARY

[0005] The imprinted film is mainly synthesized by four steps. First, silver nanocubes (Ag NCs) are synthesized: silver nitrate (AgNO3), sodium sulfide (Na2S), and polyvinylpyrrolidone (PVP) are mixed and added to ethylene glycol for stirring, after reaction, centrifugation, washing with deionized water, and drying; second, Ag@TiO2 composite nanomaterials are synthesized: the prepared Ag NCs are reacted with tetrabutyl titanate (TOBT) in a dimethylamine (DMA) solution, and then the product is centrifuged and washed with deionized water; then, the Ag NCs@TiO2 nanoparticles are blended with a polydimethylsiloxane (PDMS) elastomer matrix, a curing agent, dichloroethane, and n-hexane, and after the reaction is completed, the mixture is washed with ethanol; finally, the prepared film is surface-modified with polydopamine (pDA), and the modified film is mixed with MC-LR, ethylene glycol dimethyl acrylate (EGDMA), tris(2-phenylpyridine) iridium (III) [fac-[Ir(ppy)3]], acrylamide (AM), and methacrylic acid (MAA) in deionized water. The reaction is carried out under a xenon lamp atmosphere, and the product is washed with ethanol and water several times to remove unreacted reagents, and then further washed with a Soxhlet extractor.

[0006] The present application is realized by the following technical solutions: The high-sensitivity imprinted film for selectively detecting microcystins in water based on surface-enhanced Raman scattering is composed of Ag NCs@TiO2 nanoparticles, a PDMS film, and an imprinted polymer, the Ag NCs@TiO2 nanoparticles are uniformly dispersed on the surface of the PDMS film to form an Ag NCs@TiO2 / PDMS composite film, and the imprinted polymer is coated on the Ag NCs@TiO2 / PDMS composite film.

[0007] The preparation method of the high-sensitivity imprinted film for selectively detecting microcystins in water based on surface-enhanced Raman scattering comprises the following steps: Step 1, preparation of silver nanocubes AgNO3, Na2S, and PVP are mixed and added to ethylene glycol for stirring, after reaction, centrifugation, washing with deionized water, and drying, Ag NCs are obtained for use; Step 2, preparation of Ag NCs@TiO2 nanoparticles The prepared DMA dispersion of Ag NCs is mixed with a tetrabutyl titanate (TOBT) ethanol solution for stirring, after reaction, centrifugation, and repeated washing with ethanol, Ag NCs@TiO2 nanoparticles are obtained for use; Step 3, preparation of Ag NCs@TiO2 / PDMS composite film The Ag NCs@TiO2 nanoparticles are blended with a polydimethylsiloxane (PDMS) elastomer matrix, a curing agent, dichloroethane, n-hexane, and distilled water, and are left to stand at 70 o C for 20-40 min. Step 4, preparation of a SERS imprinting composite film (ATP-MIMs) The prepared film is subjected to surface bromination modification. The prepared Ag NCs@TiO2 / PDMS composite film is first subjected to surface amination modification with polydopamine, and then is mixed with 2-bromoisobutyryl bromide (2-BIB) and triethylamine (TEA) to perform surface bromination treatment. The brominated film is mixed with MC-LR, ethylene glycol dimethacrylate (EGDMA), tris(2-phenylpyridine)iridium (III) [fac-[Ir (ppy)3]], acrylamide (AM), and methacrylic acid (MAA) in deionized water. The product is washed with ethanol and water multiple times to remove unreacted reagents, and is further washed with a Soxhlet extractor to obtain the ATP-MIMs composite film.

[0008] In step 1, the amount ratio of the AgNO3, Na2S, PVP, and ethylene glycol is 0.4-0.6 mL: 50-150 μL: 1.0-2.0 mL: 5.0-7.0 mL, and the stirring time is 8.0-12 min.

[0009] In step 2, the amount ratio of the DMA dispersion liquid of the Ag NCs and the TOBT ethanol solution is 1.0-2.0 mL: 4.0-6.0 mL, and the stirring time is 10-20 min.

[0010] In step 3, the amount ratio of the Ag NCs@TiO2 nanoparticles, the PDMS elastomer matrix, the curing agent, dichloroethane, n-hexane, and distilled water is 0.2-0.3 g: 0.4-0.6 g: 1.0-3.0 g: 10-30 mL: 10-20 mL: 30-50 mL, and the standing time is 20-40 min.

[0011] In step 4, the amount ratio of the Ag NCs@TiO2 / PDMS composite film, dopamine, 2-BIB, and TEA is 1.0-3.0 cm 2 : 0.5 g-1.5 g: 4.0-6.0 mL: 1.0-3.0 mL, and the amount ratio of the brominated film, MC-LR, EGDMA, tris(2-phenylpyridine)iridium (III), AM, MAA, and ionized water is 1.0-3.0 cm 2: 5.0~15 μg: 1.0~3.0 mmol: 2.0~4.0 μmol: 0.1~0.3 mmol: 0~0.3 mmol: 10~30 mL, the reaction time under the xenon lamp atmosphere is 1.0~3.0 h.

[0012] In steps 1~4, the washing is all ethanol and water washing 3 times respectively.

[0013] The prepared high-sensitivity imprinting film based on surface-enhanced Raman scattering is used for selective detection of MC-LR in water.

[0014] The preparation method of the corresponding non-imprinted polymer film of the application is similar to the synthesis method as above, but without MC-LR.

[0015] Technical advantages of the application: The application combines film technology, SERS technology and photo-induced MIT, utilizes the photocatalytic degradation performance of the composite SERS substrate (Ag NCs@TiO2), so that the prepared SERS imprinting film material has the excellent physical and chemical properties of the PDMS film, the high sensitivity of the SERS detection technology and the high selectivity of the MIT, in addition, due to the photocatalytic degradation performance, the material has high cyclic detection ability (attached Figure 1 ); the application selects silver nanocube morphology as the SERS substrate material, the excellent surface plasmon resonance effect of the edge ensures the high sensitivity detection of trace MC-LR; the application utilizes the PDMS film as the supporting material of the SERS substrate, and the large surface area of the film material makes the SERS detection area larger than that of the traditional material, which improves the detection sensitivity; the application utilizes the photo-induced polymerization technology to construct the molecular imprinting composite film, utilizes the specific binding between the functional monomer and the target molecule to increase the selectivity of the traditional SERS substrate material, and realizes the accurate detection of low-concentration MC-LR (attached Figure 2 ); the application screens the best preparation condition through the optimization of the reaction condition (different Ag NCs@TiO2 nanoparticle dosage, different film thickness, different functional monomer ratio, and polymerization reaction time) (attached Figure 3 ). The results show that the SERS imprinting composite film has high detection sensitivity (attached Figure 4 ) and selectivity (attached Figure 5 ) for MC-LR, and the detection limit for MC-LR can reach 0.0313 μg·L -1 . In addition, the SERS imprinting film material exhibits strong self-cleaning ability (attached Figure 6 ) and good cyclic detection ability (attached Figure 7In recent years, PDMS membranes have attracted much attention, and their combination with SERS technology and MIT (Microcystin-Mixed Toxins) is of great significance to the development of SERS technology. A comparison of the materials mentioned in this invention with relevant international research shows that this material has significant advantages in the selective detection of biotoxins in water. The SERS-imprinted composite membrane in this invention is easy to prepare, low-cost, high-performance, and highly selective, successfully providing a promising and low-cost method for the effective detection of low concentrations of microcystin and other biotoxins in water. This technology provides a new method for SERS detection and broadens its application scope. Attached Figure Description

[0016] Figure 1 Flowchart of ATP-MIMs preparation and detection; Figure 2 SEM images of the prepared materials: (a) PDMS membrane, (b) Ag@TiO2 / PDMS membrane, (c) ATP-MIMs; Figure 3 : Optimization of preparation conditions (a: amount of Ag NCs@TiO2 nanoparticles, different film thicknesses, different functional monomer ratios, polymerization reaction time); Figure 4 (a) SERS spectra of ATP-MIMs adsorbing different concentrations of MC-LR; (b) Linear relationship between MC-LR Raman intensity and concentration; Figure 5 Selectivity of ATP-MIMs for different molecules at a concentration of 10 μg / L: (a) MC-LR, (b) R6G, (c) LC, (d) 2,6-DCP; Figure 6 The detection sensitivity of Ag NCs and Ag NCs@TiO2 / PDMS membranes for the same concentration of MC-LR.

[0017] Figure 7 ATP-MIMs' ability to detect cyclic MC-LR. Detailed Implementation

[0018] The invention will be further explained below with reference to specific implementation examples.

[0019] Example 1: (1) Preparation of silver nanocubes 0.4 mL AgNO3, 100 μL Na2S, and 1.5 mL PVP were mixed and added to 5.0 mL ethylene glycol and stirred for 8.0 min. After the reaction, the mixture was centrifuged, washed with deionized water, and dried to obtain Ag NCs for later use. (2) Ag NCs@TiO2 nanoparticles 1.5 mL of the prepared Ag NCs dimethylamine dispersion was mixed with 4.0 mL of TOBT ethanol solution and stirred for 10 min. After the reaction, the mixture was centrifuged and washed with deionized water to obtain Ag NCs@TiO2 nanoparticles for later use. (3) Preparation of Ag NCs@TiO2 / PDMS composite film 0.3 g Ag NCs@TiO2 nanoparticles were mixed with 0.4 g polydimethylsiloxane (PDMS) elastomer matrix, 3.0 g curing agent, 20 mL dichloroethane, 10 mL n-hexane, and 30 mL distilled water, and then mixed at 70 °C. o After standing for 20 min under C conditions, and after the reaction is complete, wash with ethanol to obtain Ag NCs@TiO2 / PDMS composite membrane for later use; (4) Preparation of SERS-imprinted composite membranes (ATP-MIMs) The prepared membrane was subjected to surface bromination modification, and a 1.0 cm sample was taken. 2 The prepared Ag NCs@TiO2 / PDMS composite membrane was mixed with 0.5 g dopamine, 4.0 mL bromoisobutyryl bromide (2-BIB), and 1.0 mL triethylamine (TEA) for surface bromination. The brominated membrane was then mixed with 5.0 μg MC-LR, 1.0 mmol ethylene glycol dimethacrylate (EGDMA), 2.0 μmol tris(2-phenylpyridine)iridium(III)[fac-[Ir(ppy)3]], 0.2 mmol acrylamide (AM), and 0.1 mmol methacrylic acid (MAA) in 10 mL deionized water. The reaction was carried out under a xenon lamp atmosphere for 1.0 h. The product was washed repeatedly with ethanol and water to remove unreacted reagents, and then further washed with Soxhlet extraction to obtain the ATP-MIMs composite membrane, which was ready for use.

[0020] In step 1, the ratio of AgNO3, Na2S, PVP, and ethylene glycol is 0.4 mL: 100 μL: 1.5 mL: 5.0 mL; and the stirring time is 8.0 min.

[0021] In step 2, the ratio of the DMA dispersion of Ag NCs to the TOBT ethanol solution is 1.5 mL: 4.0 mL, and the stirring time is 10 min.

[0022] In step 3, the ratio of Ag NCs@TiO2 nanoparticles, PDMS elastomer matrix, curing agent, dichloroethane, n-hexane, and distilled water is 0.3 g: 0.4 g: 3.0 g: 20 mL: 10 mL: 30 mL, and the standing time is 20 min.

[0023] In step 4, the ratio of the Ag NCs@TiO2 / PDMS composite membrane to dopamine, 2-BIB, and TEA is 1.0 cm⁻¹. 2 The ratio of the brominated membrane to MC-LR, EGDMA, tris(2-phenylpyridine)iridium(III), AM, MAA, and deionized water was 1.0 cm⁻¹. 2 The reaction mixture consisted of 5.0 μg, 1.0 mmol, 2.0 μmol, 0.2 mmol, 0.1 mmol, and 10 mL, and the reaction time under the xenon lamp atmosphere was 1.0 h.

[0024] In steps 1 to 4, the washing process involves washing three times each with ethanol and water.

[0025] The prepared high-sensitivity imprinted membrane based on surface-enhanced Raman scattering was used for the selective detection of MC-LR in water.

[0026] The preparation method of the non-imprinted polymeric membrane corresponding to this invention is similar to the synthesis method described above, but without the addition of MC-LR.

[0027] Example 2: (1) Preparation of silver nanocubes 0.5 mL AgNO3, 50 μL Na2S, and 1.5 mL PVP were mixed and added to 7.0 mL ethylene glycol and stirred for 10.0 min. After the reaction, the mixture was centrifuged, washed with deionized water, and dried to obtain Ag NCs for later use. (2) Ag NCs@TiO2 nanoparticles 1.0 mL of the prepared Ag NCs DMA dispersion was mixed with 5.0 mL of TOBT ethanol solution and stirred for 15 min. After the reaction, the mixture was centrifuged and washed with deionized water to obtain Ag NCs@TiO2 nanoparticles for later use. (3) Preparation of Ag NCs@TiO2 / PDMS composite film 0.2 g Ag NCs@TiO2 nanoparticles were mixed with 0.5 g PDMS elastomer matrix, 2.0 g curing agent, 10 mL dichloroethane, 15 mL n-hexane, and 40 mL distilled water, and then mixed at 70 °C. o After standing for 30 min under C conditions, and after the reaction is complete, wash with ethanol to obtain Ag NCs@TiO2 / PDMS composite membrane for later use; (4) Preparation of SERS-imprinted composite membranes (ATP-MIMs) The prepared membrane was subjected to surface bromination modification, and a 2.0 cm sample was taken. 2The prepared Ag NCs@TiO2 / PDMS composite membrane was mixed with 1.0 g dopamine, 5.0 mL 2-BIB, and 2.0 mL TEA for surface bromination. The brominated membrane was then mixed with 10 μg MC-LR, 2.0 mmol EGDMA, 3.0 μmol tris(2-phenylpyridine)iridium(III)[fac-[Ir(ppy)3]], 0.1 mmol AM, and 0.1 mmol MAA in 20 mL deionized water. The reaction was carried out under a xenon lamp atmosphere for 2.0 h. The product was washed repeatedly with ethanol and water to remove unreacted reagents, and then further washed with Soxhlet extraction to obtain the PCA-MIMs composite membrane, which was ready for use.

[0028] In step 1, the ratio of AgNO3, Na2S, PVP, and ethylene glycol is 0.5 mL: 50 μL: 1.5 mL: 7.0 mL; and the stirring time is 10.0 min.

[0029] In step 2, the ratio of the DMA dispersion of Ag NCs to the TOBT ethanol solution is 1.0 mL: 5.0 mL, and the stirring time is 15 min.

[0030] In step 3, the ratio of Ag NCs@TiO2 nanoparticles, PDMS elastomer matrix, curing agent, dichloroethane, n-hexane, and distilled water is 0.2 g: 0.5 g: 2.0 g: 10 mL: 15 mL: 40 mL, and the standing time is 30 min.

[0031] In step 4, the ratio of the Ag NCs@TiO2 / PDMS composite membrane to dopamine, 2-BIB, and TEA is 2.0 cm⁻¹. 2 The ratio of brominated membrane to MC-LR, EGDMA, tris(2-phenylpyridine)iridium(III), AM, MAA, and deionized water was 1.0 g: 5.0 mL: 2.0 mL, with a volume ratio of 2.0 cm⁻¹. 2 The reaction mixture consisted of 10 μg, 2.0 mmol, 3.0 μmol, 0.1 mmol, and 0.1 mmol in 20 mL. The reaction time under the xenon lamp atmosphere was 2.0 h.

[0032] In steps 1 to 4, the washing process involves washing three times each with ethanol and water.

[0033] The prepared high-sensitivity imprinted membrane based on surface-enhanced Raman scattering was used for the selective detection of MC-LR in water.

[0034] The preparation method of the non-imprinted polymeric membrane corresponding to this invention is similar to the synthesis method described above, but without the addition of MC-LR.

[0035] Example 3: (1) Preparation of silver nanocubes 0.6 mL AgNO3, 150 μL Na2S, and 2.0 mL PVP were mixed and added to 7.0 mL ethylene glycol and stirred for 12.0 min. After the reaction, the mixture was centrifuged, washed with deionized water, and dried to obtain Ag NCs for later use. (2) Ag NCs@TiO2 nanoparticles 2.0 mL of the prepared Ag NCs DMA dispersion was mixed with 6.0 mL of TOBT ethanol solution and stirred for 20 min. After the reaction, the mixture was centrifuged and washed with deionized water to obtain Ag NCs@TiO2 nanoparticles for later use. (3) Preparation of Ag NCs@TiO2 / PDMS composite film 0.3 g Ag NCs@TiO2 nanoparticles were mixed with 0.6 g PDMS elastomer matrix, 3.0 g curing agent, 30 mL dichloroethane, 20 mL n-hexane, and 50 mL distilled water, and then heated at 70 °C. o After standing for 40 min under C conditions, and after the reaction is complete, wash with ethanol to obtain Ag NCs@TiO2 / PDMS composite membrane for later use; (4) Preparation of SERS-imprinted composite membranes (ATP-MIMs) The prepared membrane was subjected to surface bromination modification, and a 3.0 cm sample was taken. 2 The prepared Ag NCs@TiO2 / PDMS composite membrane was mixed with 1.5 g dopamine, 6.0 mL 2-BIB, and 3.0 mL TEA for surface bromination. The brominated membrane was then mixed with 15 μg MC-LR, 3.0 mmol EGDMA, 4.0 μmol tris(2-phenylpyridine)iridium(III)[fac-[Ir(ppy)3]], 0.3 mmol AM, and 0.2 mmol MAA in 30 mL deionized water. The reaction was carried out under a xenon lamp atmosphere for 3.0 h. The product was washed repeatedly with ethanol and water to remove unreacted reagents, and then further washed with Soxhlet extraction to obtain the ATP-MIMs composite membrane for later use.

[0036] In step 1, the ratio of AgNO3, Na2S, PVP, and ethylene glycol is 0.6 mL: 150 μL: 2.0 mL: 7.0 mL; and the stirring time is 12.0 min.

[0037] In step 2, the ratio of the DMA dispersion of Ag NCs to the TOBT ethanol solution is 2.0 mL: 6.0 mL, and the stirring time is 20 min.

[0038] In step 3, the ratio of Ag NCs@TiO2 nanoparticles, PDMS elastomer matrix, curing agent, dichloroethane, n-hexane, and distilled water is 0.3 g: 0.6 g: 3.0 g: 30 mL: 20 mL: 50 mL, and the standing time is 40 min.

[0039] In step 4, the ratio of the Ag NCs@TiO2 / PDMS composite membrane to dopamine, 2-BIB, and TEA is 3.0 cm⁻¹. 2 The ratio of brominated membrane to MC-LR, EGDMA, tris(2-phenylpyridine)iridium(III), AM, MAA, and deionized water was 1.5 g: 6.0 mL: 3.0 mL, with a volume ratio of 3.0 cm⁻¹. 2 The reaction mixture consisted of 15 μg, 3.0 mmol, 4.0 μmol, 0.3 mmol, 0.2 mmol, and 30 mL, and the reaction time under the xenon lamp atmosphere was 3.0 h.

[0040] In steps 1 to 4, the washing process involves washing three times each with ethanol and water.

[0041] The prepared high-sensitivity imprinted membrane based on surface-enhanced Raman scattering was used for the selective detection of MC-LR in water.

[0042] The preparation method of the non-imprinted polymeric membrane corresponding to this invention is similar to the synthesis method described above, but without the addition of MC-LR.

[0043] In a specific embodiment of this invention, the detection capability evaluation was performed as follows: All SERS substrates with different concentrations of MC-LR adsorbed were air-dried and then laid flat on a glass slide. Excitation was 514 nm, and the exposure time for spectral acquisition of each sample was 10 s with an incident laser power of 15 mW. A 50× Nikon lens was used for SERS spectrum collection. A curve was plotted with the MC-LR concentration [c] on the x-axis and the SERS intensity on the y-axis.

[0044] Experimental Example 1: First, the Raman intensities of ATP-MIMs adsorbing different concentrations of MC-LR were measured. Then, the linear relationship between Raman intensity and MC-LR concentration was investigated. Preparations were prepared ranging from 0.1 to 10 μg·L⁻¹. -1 Six ATP-MIMs were aliquoted into a centrifuge tube and added to a MC-LR solution of different concentrations for adsorption. After adsorption was complete, the membranes were allowed to air dry, laid flat on a glass slide, placed under an objective lens, and the lens was adjusted before measuring the Raman intensity. Figure 4 As shown, at 1644 cm -1It can be observed that as the concentration of MC-LR gradually decreases, the Raman intensity decreases, and the two show a linear relationship.

[0045] Experimental Example 2: The selectivity of ATP-MIMs for MC-LR, rhodamine 6G (R6G), cypermethrin (LC), and 2,6-dichlorophenol (2,6-DCP) was investigated. MC-LR, R6G, LC, and 2,6-DCP were prepared at a concentration of 10 μg·L⁻¹. -1 The solutions were prepared by adding 10 mL of MC-LR, R6G, LC, and 2,6-DCP solutions and one ATP-MIMs membrane to a centrifuge tube for adsorption. After adsorption was complete, the membranes were allowed to air dry, laid flat on a glass slide, placed under an objective lens, and the Raman intensity was measured. Figure 5 As shown, the prepared ATP-MIMs were prepared at a concentration of 10 μg·L⁻¹. -1 Under certain conditions, the selectivity for MC-LR is stronger, and there is also selectivity for R6G, LC, and 2,6-DCP, but it is weaker than that for MC-LR. The results indicate that ATP-MIMs have good selectivity for MC-LR.

[0046] Experimental Example 3: The cyclicity of ATP-MIMs was investigated. After using ATP-MIMs for selective detection of MC-LR in water, they were irradiated under ultraviolet light for a period of time, and the residual pollutant components on their surface were measured. The results showed that after sufficient ultraviolet irradiation, molecules adsorbed on the surface of ATP-MIMs were effectively removed. This is attributed to the photocatalytic degradation properties of ATP-MIMs themselves, which can effectively remove pollutant molecules adsorbed on their surface, thereby improving their cyclic detection capability.

[0047] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A highly sensitive imprinted membrane for selective detection of microcystin toxins in water based on surface-enhanced Raman scattering, wherein the imprinted membrane is composed of Ag NCs@TiO2 nanoparticles, a PDMS membrane, and an imprinted polymer, wherein the Ag NCs@TiO2 nanoparticles are uniformly dispersed on the surface of the PDMS membrane to form an Ag NCs@TiO2 / PDMS composite membrane, and the imprinted polymer is coated on the outside of the AgNCs@TiO2 / PDMS composite membrane.

2. A method for preparing a highly sensitive imprinted membrane based on surface-enhanced Raman scattering for the selective detection of microcystin-releasing agents (MC-LR) in water, as described in claim 1, characterized in that, The steps are as follows: Step 1: Preparation of silver nanocubes AgNO3, Na2S, and PVP were mixed and added to ethylene glycol and stirred. After the reaction, the mixture was centrifuged, washed with deionized water, and dried to obtain Ag NCs for later use. Step 2, Ag NCs@TiO2 nanoparticles The prepared Ag NCs DMA dispersion was mixed and stirred with tetrabutyl titanate (TOBT) ethanol solution. After reaction, the mixture was centrifuged and repeatedly washed with ethanol to obtain Ag NCs@TiO2 nanoparticles for later use. Step 3: Preparation of Ag NCs@TiO2 / PDMS composite film Ag NCs@TiO2 nanoparticles were blended with a polydimethylsiloxane (PDMS) elastomer matrix, a curing agent, dichloroethane, n-hexane, and distilled water, and then mixed at 70 °C. o After standing at C conditions until the reaction is complete, the membrane is washed with ethanol to obtain Ag NCs@TiO2 / PDMS composite membrane, which is ready for use. Step 4: Preparation of SERS-imprinted composite membranes (ATP-MIMs) The prepared membrane was subjected to surface bromination modification. The prepared Ag NCs@TiO2 / PDMS composite membrane was first surface-aminated with polydopamine, and then mixed with bromoisobutyryl bromide (2-BIB) and triethylamine (TEA) for surface bromination treatment. The brominated membrane was then mixed with MC-LR, ethylene glycol dimethacrylate (EGDMA), tris(2-phenylpyridine)iridium(III)[fac-[Ir(ppy)3]], acrylamide (AM), and methacrylic acid (MAA) in deionized water. The reaction was carried out under a xenon lamp atmosphere. The product was washed repeatedly with ethanol and water to remove unreacted reagents, and then further washed with Soxhlet extraction to obtain the ATP-MIMs composite membrane for later use.

3. The method for preparing a highly sensitive imprinted membrane for selective detection of microcystin in water based on surface-enhanced Raman scattering as described in claim 2, characterized in that, In step 1, the ratio of AgNO3, Na2S, PVP, and ethylene glycol is 0.4~0.6 mL: 50~150 μL: 1.0~2.0 mL: 5.0~7.0 mL; the stirring time is 8.0~12 min.

4. The method for preparing a highly sensitive imprinted membrane for selective detection of microcystin in water based on surface-enhanced Raman scattering as described in claim 2, characterized in that, In step 2, the ratio of the DMA dispersion of Ag NCs to the TOBT ethanol solution is 1.0~2.0 mL: 4.0~6.0 mL, and the stirring time is 10~20 min.

5. The method for preparing a highly sensitive imprinted membrane for selective detection of microcystin in water based on surface-enhanced Raman scattering as described in claim 2, characterized in that, In step 3, the ratio of Ag NCs@TiO2 nanoparticles, PDMS elastomer matrix, curing agent, dichloroethane, n-hexane, and distilled water is 0.2~0.3 g: 0.4~0.6 g: 1.0~3.0 g: 10~30 mL: 10~20 mL: 30~50 mL, and the standing time is 20~40 min.

6. The method for preparing a highly sensitive imprinted membrane for selective detection of microcystin in water based on surface-enhanced Raman scattering as described in claim 2, characterized in that, In step 4, the ratio of the Ag NCs@TiO2 / PDMS composite membrane to dopamine, 2-BIB, and TEA is 1.0~3.0 cm. 2 The dosage ratio of the brominated membrane to MC-LR, EGDMA, tris(2-phenylpyridine)iridium(III), AM, MAA, and deionized water is 1.0–3.0 cm⁻¹. 2 : 5.0~15 μg; 1.0~3.0 mmol; 2.0~4.0 μmol; 0.1~0.3 mmol; 0~0.3 mmol; 10~30 mL, the reaction time under the xenon lamp atmosphere is 1.0~3.0 h.

7. The method for preparing a highly sensitive imprinted membrane for selective detection of microcystin in water based on surface-enhanced Raman scattering as described in claim 2, characterized in that, In steps 1 to 4, the washing process involves washing three times each with ethanol and water.

8. The high-sensitivity imprinted membrane based on surface-enhanced Raman scattering as described in claim 1 for selectively adsorbing microcystin (MC-LR) in water.

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