Nanogold modified mesoporous MXene material, and preparation method and application thereof

Abstract

This invention provides a nano-gold-modified mesoporous MXene material, its preparation method, and its application, belonging to the field of detection and testing technology. This invention employs a high redox potential difference-driven oxidation strategy to prepare uniformly mesoporous Ti3C2T. x The material was cross-linked with PDDA; gold nanoparticles were attached to mesoporous Ti3C2T x On the membrane surface, mesoporous MXene material modified with gold nanoparticles was obtained. Using the specific preparation conditions of this invention, mesoporous Ti3C2T... x Effective combination with nano-gold, gold substrate and Ti3C2T x The markers can exert a synergistic enhancement effect on SERS, which can improve the detection sensitivity and realize the function of surface-enhanced Raman spectroscopy for solid-phase substrate determination. This is beneficial for the detection of quinolone antibiotics such as ciprofloxacin in agricultural products and food, and provides semi-quantitative detection results.

Description

Technical Field

[0001] This invention relates to the field of detection and testing technology, and in particular to a nano-gold modified mesoporous MXene material, its preparation method, and its application. Background Technology

[0002] Quinolone antibiotics are a class of broad-spectrum, highly effective bactericidal and bacteriostatic antibiotics that have been widely used in livestock production due to their good antibacterial effects. However, it is worth noting that excessive intake or long-term low-dose intake of quinolone antibiotics can cause dysbiosis, hyperactivity, muscle damage, and cardiac discomfort in humans, among other toxic side effects. Traditional quinolone detection primarily relies on liquid chromatography-tandem mass spectrometry (LC-MS / MS), but practical detection faces challenges such as high operational requirements and high maintenance costs for mass spectrometers. Therefore, finding a rapid detection method for quinolone additives in traditional Chinese medicine veterinary products is urgently needed.

[0003] Surface-enhanced Raman spectroscopy (SERS) primarily relies on nanomaterials of noble metals as the active substrate. However, using noble metal particles as the active substrate has two main drawbacks: First, noble metal particles tend to aggregate over long periods, requiring the use of coagulators during detection. Second, the agglomeration and adsorption of noble metal nanoparticles reduce the inter-day stability of the detection and increase the cost of the noble metal nanomaterials. Third, although small-diameter noble metal nanoparticles possess strong surface plasmon resonance and a large specific surface area, relatively dispersed noble metal nanoparticles still struggle to enhance the Raman signal. Therefore, providing a low-cost, highly stable SERS solid substrate is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a gold nanoparticle-modified mesoporous MXene material, its preparation method and application. The gold nanoparticle-modified mesoporous MXene material can be used as a stable SERS solid substrate and is low in cost.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a gold nanoparticle-modified mesoporous MXene material, comprising the following steps: Ti3C2T x The material is dispersed in water, and the resulting Ti3C2T x The dispersion was mixed with copper salt solution and hydrogen peroxide solution to carry out an oxidation reaction. The resulting product was mixed with hydrofluoric acid and etched to obtain mesoporous Ti3C2T. x Material; The mesoporous Ti3C2T x The material was mixed with polydiallyldimethylammonium chloride and water to undergo a crosslinking reaction, yielding PDDA-modified Ti3C2T.x ; Modify Ti3C2T with PDDA x It adheres to the substrate surface to obtain a modified substrate; By attaching gold nanoparticles to a modified substrate, a gold nanoparticle-modified mesoporous MXene material is obtained.

[0006] Preferably, the concentration of the copper salt solution is 0.5~2 mol / L, the mass concentration of the hydrogen peroxide solution is 10~50%, and the volume ratio of the copper salt solution to the hydrogen peroxide solution is 100~200:50~100. The Ti3C2T x The concentration of the dispersion is 2~6 mg / mL, and the Ti3C2T x The volume ratio of the dispersion to the copper salt solution is (10~30)×10. 3 65~85.

[0007] Preferably, the oxidation reaction is carried out at a temperature of 40-45°C for a time of 15-45 minutes. The mesoporous Ti3C2T x The material has a pore size of 2~50 nm.

[0008] Preferably, the molecular weight of the polydiallyl dimethylammonium chloride is 100-200k, and the mesoporous Ti3C2T x The mass ratio of the material to polydiallyldimethylammonium chloride is 1:20~30.

[0009] Preferably, the crosslinking reaction is carried out at a temperature of 30-40°C for 5-7 hours.

[0010] Preferably, the gold nanoparticles in the gold nanoparticle sol are prepared by growth synthesis; the particle size of the gold nanoparticles is 70~90 nm.

[0011] Preferably, the PDDA-modified Ti3C2T x The mass ratio of the nanoparticles to gold nanoparticles is 0 to 5:100 and is not 0.

[0012] Preferably, the loading amount of the gold nanoparticles on the modified substrate is 2~100 mg / cm³. 2 .

[0013] This invention provides a nano-gold modified mesoporous MXene material prepared by the preparation method described above.

[0014] This invention provides the application of the nano-gold modified mesoporous MXene material described above in the detection of quinolone antibiotics using surface-enhanced Raman spectroscopy.

[0015] This invention employs a high redox potential difference-driven oxidation strategy to prepare mesoporous Ti3C2T. x The material was cross-linked with PDDA; gold nanoparticles were attached to mesoporous Ti3C2T x On the membrane surface, mesoporous MXene material modified with gold nanoparticles was obtained. Polydiallyl dimethylammonium chloride (PDDA) was used to modify the mesoporous Ti3C2T... x Effective cross-linking and bonding with nano-gold, gold substrate and Ti3C2T x The markers can exert a synergistic enhancement effect on SERS. MXene is a two-dimensional material that can effectively adsorb compounds with heterocyclic and aromatic structures. AuNPs can achieve non-specific SERS enhancement of the above-mentioned organic compounds. At the same time, mesoporous MXene can also exert a synergistic enhancement effect, thereby improving the detection sensitivity and realizing the function of solid-phase substrate determination of surface-enhanced Raman spectroscopy. This is beneficial for the detection of quinolone antibiotics such as ciprofloxacin in agricultural products and food, and provides semi-quantitative detection results.

[0016] The paper-based mesoporous Ti3C2T based on nano-gold modification prepared in this invention x The material enables efficient and rapid detection of quinolone antibiotics such as ciprofloxacin in food, as well as efficient detection of chemical drug additives in traditional Chinese veterinary medicine.

[0017] The MXene material based on gold nanoparticle modification prepared in this invention can effectively realize the determination of surface-enhanced Raman spectroscopy in a solid-phase matrix, and enhance the stability of the surface-enhanced Raman active substrate (using a low molecular weight crosslinking agent, polydiallyldimethylammonium chloride, to crosslink the MXene material and AuNPs material can improve the uniformity of the material, thereby improving the stability effect). This is beneficial to increasing the possibility of long-term storage of the material and the stability of the results determination, greatly enhancing the rapid and effective detection of pesticide residues, traditional Chinese veterinary drug residues, and illegally added ingredients in antibiotic substitutes, and improving the efficiency of food safety testing.

[0018] The MXene material based on gold nanoparticle modification prepared by this invention can be widely used in the field of biosensor technology and has strong practicality. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of the nano-gold modified mesoporous MXene material of the present invention; Figure 2 Example 1: Intermediate Hole Ti3C2T x Electron microscopy characterization of materials ( Figure 2In the image, A is a transmission electron microscope image of the mesoporous MXene material, B is a high-resolution transmission electron microscope image of the mesoporous modified MXene, and C is an atomic force microscope image. Figure 3 The images shown are transmission electron microscope images (A) and particle size distribution diagrams (B) of the AuNPs material in Example 1. Figure 4 Example 1: Intermediate Hole Ti3C2T x Nitrogen desorption characterization diagram of the material ( Figure 4 In the diagram, A represents the intermediate hole Ti3C2T in Example 1. x Material specific surface area; B represents the mesopore Ti3C2T of Example 1. x Nitrogen desorption cycle diagram of the material; C represents mesoporous Ti3C2T from Example 1. x (Aperture distribution diagram); Figure 5 For example 1, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity verification diagram of the substrate ( Figure 5 In the diagram, A represents the theoretical Raman spectrum of methylene blue and the SERS spectrum of the AuNPs substrate in Test Example 1. PDDA-AuNPs / mesoporous Ti3C2T x B is the SERS spectrum of the substrate; C is the SERS spectrum of methylene blue in Test Example 1 using smooth and rough surfaces; D is the SERS spectrum of methylene blue at a concentration of 10 ng / mL in Test Example 1 on PDDA-AuNPs / mesoporous Ti3C2T. x SERS spectra of the substrate and AuNPs substrate; D represents the PDDA-AuNPs / mesoporous Ti3C2T prepared using different amounts of AuNPs in Test Example 1. x SERS intensity of the substrate). Figure 6 In the text, A represents PDDA-AuNPs / mesoporous Ti3C2T in Test Example 1. x Concentration-response relationship analysis of the substrate to different concentrations of methylene blue; B is the stability analysis of test example 1; Figure 7 For example 1, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity uniformity diagrams of the substrates (A is the SERS spectrum of AuNPs substrate prepared without PDDA in Test Example 1; B is the SERS spectrum of PDDA-AuNPs / mesoporous Ti3C2T prepared using PDDA with a molecular weight of 100k-200k in Test Example 1). x SERS spectrum of the substrate; C represents PDDA-AuNPs / mesoporous Ti3C2T prepared using PDDA with a molecular weight of 100k-200k in Test Example 1.x SERS spectrum of the substrate); Figure 8 In the text, A represents PDDA-AuNPs / mesoporous Ti3C2T in Test Example 1. x SERS spectrum of 100 methylene blue on the substrate; B test example 1 PDDA-AuNPs / mesoporous Ti3C2T x SERS mapping of the substrate with 100 methylene blue stains; PDDA-AuNPs / mesoporous Ti3C2T in C test example 1 x SERS mapping histogram of 100 methylene blue layers on the substrate; Figure 9 In Test Example 2, PDDA-AuNPs / mesoporous Ti3C2T was used. x PDDA-mesoporous Ti3C2T x Mesoporous Ti3C2T x SERS spectrum of ciprofloxacin at the base stage; Figure 9 In test example B, PDDA-AuNPs / mesoporous Ti3C2T is used. x Concentration-response relationship analysis of the substrate to different concentrations of ciprofloxacin. Figure 9 C in the middle represents the use of PDDA-AuNPs / mesoporous Ti3C2T x Concentration-response linear relationship graph when detecting ciprofloxacin standard in substrate; Figure 10 For example 2, PDDA-AuNPs / mesoporous Ti3C2T were used. x SERS spectrum of ciprofloxacin as a base ( Figure 10 In the diagram, A represents the theoretical Raman spectrum of ciprofloxacin in test example 2, and PDDA-AuNPs / mesoporous Ti3C2T. x SERS spectrum of the substrate; BC represents PDDA-AuNPs / mesoporous Ti3C2T prepared using PDDA in Test Example 2. x SERS spectra (B) and first derivative plots (C) of ciprofloxacin, enrofloxacin, norfloxacin, and enoxacin on the substrate; D is the SERS spectrum (B) of PDDA-AuNPs / mesoporous Ti3C2T used in test example 2. x Principal component analysis plots of SERS spectra of ciprofloxacin, enrofloxacin, norfloxacin, and enoxacin at the base stage; Figure 11 In the diagram, A represents the PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x The intraday stability analysis of ciprofloxacin determined at substrate temperature is shown in Figure B, where B represents the PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x A graph showing the daytime stability analysis of ciprofloxacin determined at the base time. Figure 12 For example 2, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity uniformity diagram of the substrate ( Figure 12 In the diagram, A represents the PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x SERS spectra of ciprofloxacin extracted from milk using different solvents in the substrate; B is the SERS spectrum of PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x The SERS response intensity of the substrate using different purifiers; C represents the SERS response intensity of PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x SERS spectrum of the substrate; D represents PDDA-AuNPs / mesoporous Ti3C2T in test example 2. x (Base determination: SERS concentration-response relationship graph of ciprofloxacin in milk). Figure 13 For example 2, PDDA-AuNPs / mesoporous Ti3C2T x SERS concentration-response relationship of ciprofloxacin in milk as determined by substrate analysis; Figure 14 PDDA-AuNPs / mesoporous Ti3C2T in Example 1 x SERS enhancement mechanism diagram of substrate ( Figure 14 In the diagram, A represents the SERS spectrum of the AuNPs substrate prepared without PDDA; B represents the PDDA-AuNPs / mesoporous Ti3C2T substrate from Example 1. x SERS spectrum of the substrate; C represents PDDA-AuNPs / mesoporous Ti3C2T in Example 1. x SERS spectrum of the substrate; D represents the mesoporous Ti3C2T substrate of Example 1. x 3D structural diagram of the substrate; E represents the intermediate hole Ti3C2T in Example 1. x Density state distribution diagram of the substrate; F represents the mesopore Ti3C2T in Example 1. x (Electron transfer between the substrate and ciprofloxacin molecules). Detailed Implementation

[0020] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0021] like Figure 1 As shown, this invention provides a method for preparing a gold nanoparticle-modified mesoporous MXene material, comprising the following steps: Ti3C2T x The material is dispersed in water, and the resulting Ti3C2T xThe dispersion was mixed with copper salt solution and hydrogen peroxide solution to carry out an oxidation reaction. The resulting product was mixed with hydrofluoric acid and etched to obtain mesoporous Ti3C2T. x Material; The mesoporous Ti3C2T x The material was mixed with polydiallyldimethylammonium chloride and water to undergo a crosslinking reaction, yielding PDDA-modified Ti3C2T. x ; Modify Ti3C2T with PDDA x It adheres to the substrate surface to obtain a modified substrate; By attaching gold nanoparticles to a modified substrate, a gold nanoparticle-modified mesoporous MXene material is obtained.

[0022] This invention uses Ti3C2T x The material is dispersed in water, and the resulting Ti3C2T x The dispersion was mixed with copper salt solution and hydrogen peroxide solution to carry out an oxidation reaction. The resulting product was mixed with hydrofluoric acid and etched to obtain mesoporous Ti3C2T. x Material.

[0023] In this invention, the Ti3C2T x The preferred method for preparing the material is as follows: mixing and reacting Ti3AlC2 material, lithium fluoride, and hydrochloric acid solution, followed by etching, to obtain Ti3C2T. x Material.

[0024] In this invention, the mass fraction of the hydrochloric acid solution is preferably 36-38%, more preferably 37%; the ratio of the amount of Ti3AlC2 material, lithium fluoride and hydrochloric acid solution is 0.5-1.5g:1.1-2.1g:15-25mL, more preferably 0.7-1.3g:1.3-1.8g:17-23mL, and more preferably 1-1.1g:1.6-1.7g:20-21mL.

[0025] In this invention, Cu ions act as an effective catalyst to catalyze the decomposition of hydrogen peroxide, generating hydroxyl radicals with extremely strong oxidizing properties. The two are used together to form an oxidation reaction, forming TiO2 quantum dots on the MXene surface. Then, hydrofluoric acid is used to etch away the quantum dots to form mesoporous structures.

[0026] In this invention, the etching temperature is preferably 25~35℃, more preferably 25~30℃, and the etching time is preferably 22~26h, more preferably 24h.

[0027] After etching, the sample was washed with deionized water and vortexed for 0.5 h to obtain Ti3C2T. x Material suspension.

[0028] In this invention, the Ti3C2T x The concentration of the dispersion is preferably 2-6 mg / mL, more preferably 2-4 mg / mL; the copper salt in the copper salt solution is preferably copper sulfate, and the copper salt solution is preferably an aqueous solution of copper salt; the concentration of the copper salt solution is preferably 0.5-2 mol / L, more preferably 1-1.5 mol / L; the mass concentration of the hydrogen peroxide solution is preferably 10-50%, more preferably 30%; the Ti3C2T x The preferred volume ratio of the dispersion to the copper salt solution is (10~30)×10. 3 The volume ratio of the copper salt solution to the hydrogen peroxide solution is preferably 100-200:50-100, more preferably 2:1.

[0029] The present invention preferably uses Ti3C2T x The suspension was added to water and stirred for 10 min to obtain Ti3C2T. x The dispersion was subjected to an oxidation reaction by adding copper sulfate solution and hydrogen peroxide solution.

[0030] In this invention, the temperature of the oxidation reaction is preferably 40~45℃, more preferably 42~45℃, and the time is preferably 15~45min, more preferably 20~30min.

[0031] After the oxidation reaction is completed, the present invention preferably collects the obtained Ti3C2T by centrifugation. x / TiO2 material, after washing three times with water, the resulting product is dispersed in water, hydrofluoric acid (preferably 20-60 wt%, more preferably 40 wt%) is added, and etching is performed for 30 min (to remove TiO2). The product is collected by centrifugation and washed three times with water and ethanol respectively to obtain mesoporous Ti3C2T x Materials: The present invention does not have a special limitation on the amount of hydrofluoric acid used; sufficient amount should be used to ensure complete etching according to actual needs.

[0032] In this invention, the mesoporous Ti3C2T x The preferred pore size of the material is 2 to 50 nm.

[0033] Mesoporous Ti3C2T x Following the material, the present invention will use the mesoporous Ti3C2T x The material was mixed with polydiallyl dimethylammonium chloride (PDDA) and water to undergo a crosslinking reaction, yielding PDDA-modified Ti3C2T. x .

[0034] In this invention, the molecular weight of the polydiallyl dimethylammonium chloride is preferably 100-200k, and the mesoporous Ti3C2Tx The mass ratio of the material to polydiallyldimethylammonium chloride is preferably 1:20~30, more preferably 1:22~28, and even more preferably 1:25~26.

[0035] The present invention preferably involves mixing PDDA with water, and then reacting the resulting PDDA aqueous solution with mesoporous Ti3C2T. x The materials are mixed and cross-linked under stirring conditions; the concentration of the polydiallyldimethylammonium chloride aqueous solution is preferably 10-30%, more preferably 20%.

[0036] In this invention, the temperature of the crosslinking reaction is preferably 30~40℃, more preferably 35℃, the time is preferably 5~7h, more preferably 6h, and the stirring rate is preferably 600rpm.

[0037] After the crosslinking reaction is completed, the product is preferably washed three times by centrifugation with deionized water to obtain PDDA-modified Ti3C2T. x (PDDA-Ti3C2T) x ).

[0038] PDDA-modified Ti3C2T x Subsequently, the present invention modifies Ti3C2T with the PDDA. x The modified substrate is obtained by attaching it to the substrate surface. The nano-gold particles sol is then attached to the modified substrate to obtain nano-gold modified mesoporous MXene material.

[0039] This invention does not specifically limit the type of substrate; any Raman-enhanced substrate well-known in the art is acceptable. In embodiments of this invention, the substrate is preferably 1.5 cm². 2 The square glass fiber filter paper with a rough surface increases the adsorption of target analytes, thereby further enhancing the signal.

[0040] In this invention, the preferred method of attachment is to modify Ti3C2T with PDDA. x An aqueous dispersion was added to the substrate surface, and after vacuum drying, a modified substrate was obtained.

[0041] In this invention, the PDDA-modified Ti3C2T x The concentration of the aqueous dispersion is preferably 2 mg / mL.

[0042] In this invention, the preferred method for preparing the gold nanoparticles in the gold nanoparticle sol is growth synthesis; the preferred particle size of the gold nanoparticles is 70~90 nm.

[0043] In this invention, the preferred method for preparing the gold nanoparticle sol is as follows: chloroauric acid is dissolved in ultrapure water to obtain a chloroauric acid solution; a 0.1 mol / L sodium borohydride solution (prepared fresh for immediate use) and a 0.04 mol / L trisodium citrate solution are prepared; 0.7 mL of chloroauric acid solution and 1 mL of trisodium citrate solution are added to 100 mL of ultrapure water, stirred evenly at room temperature, and then 4 mL of freshly prepared sodium borohydride solution is quickly added; the mixture is stirred rapidly and evenly, and then the stirring speed is slowed down (800 rpm). The reaction is continued at room temperature for 30 min to obtain a gold nanoparticle seed dispersion; 1 mL of AuNPs seed dispersion is placed in an ice bath, diluted with ultrapure water, and then 0.225 mL of 1% ascorbic acid is added as a reducing agent, and 0.03 mL of sodium citrate is added as a protective agent; the mixture is stirred rapidly and evenly; 0.15 mL of HAuCl4 solution is added to a round-bottom flask, and the color changes from wine red to purplish red. The mixture is stirred continuously for 30 min to obtain the gold nanoparticle sol. The concentration of the chloroauric acid solution is preferably 0.01~0.2 g / mL, more preferably 0.01~0.1 g / mL, and even more preferably 0.02~0.05 g / mL.

[0044] In this invention, gold nanoparticle sol is preferably dropped onto a modified substrate and dried under vacuum to obtain a gold nanoparticle-modified mesoporous MXene material.

[0045] In this invention, the concentration of the gold nanoparticle sol is preferably 50-200 mg / mL, more preferably 100-200 mg / mL; the gold nanoparticle sol is preferably added dropwise in 3-4 portions.

[0046] In this invention, the PDDA-modified Ti3C2T x The mass ratio of the nano-gold particles to the gold nanoparticles is preferably 0 to 5:100 and not 0, more preferably 0.5 to 3:100, and even more preferably 1 to 2:100.

[0047] In this invention, the loading amount of the gold nanoparticles on the modified substrate is preferably 2~100 mg / cm³. 2 More preferably 10~50 mg / cm³ 2 Further preferred concentration is 26.66~30 mg / cm³. 2 .

[0048] This invention provides a nano-gold modified mesoporous MXene material prepared by the preparation method described above.

[0049] This invention provides the application of the gold-modified mesoporous MXene material described above in surface-enhanced Raman spectroscopy (SERS) for the detection of quinolone antibiotics. The method for this application is not particularly limited; the gold-modified mesoporous MXene material can be used as the SERS substrate according to methods well-known in the art.

[0050] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0051] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.

[0052] Example 1

[0053] 1 g of Ti3AlC2 material, 1.6 g of lithium fluoride, and 20 mL of hydrochloric acid solution (37% by mass) were mixed and reacted. The mixture was etched at 25 °C for 24 h, washed with 50 mL of deionized water, and vortexed for 0.5 h to obtain Ti3C2T. x Suspension; 4 mL of the above Ti3C2T was added under stirring. x The suspension was added to 26 mL of deionized water for 10 min to form Ti3C2T. x Dispersion (concentration 2 mg / mL); then 150 μL of 1 mol / L CuSO4 aqueous solution and 75 μL of 30% H2O2 solution were added to the above 30 mL Ti3C2T x After oxidation at 45°C for 30 min in the dispersion, Ti3C2T was collected by centrifugation. x The TiO2 material was washed three times with water, then dispersed in 60 mL of water, and 150 μL of HF solution (40 wt%) was added. The mixture was etched for 30 min, and the product was collected by centrifugation. The product was then washed three times with water and three times with ethanol to obtain mesoporous Ti3C2T. x Material with a pore size of 2~50 nm; Take the mesoporous Ti3C2T prepared above x The material was mixed with 20 mL of PDDA (Mw: 100k-200k, 20wt% aqueous solution) to form mesoporous Ti3C2T xThe material was reacted with polydiallyldimethylammonium chloride at a mass ratio of 1:25 at 35°C and 600 rpm for 6 h. After washing three times with deionized water and reconstituted with deionized water to 10 mL, PDDA-Ti3C2T was obtained. x Dispersion (concentration 2 mg / mL); Prepare a chloroauric acid solution (0.02 g / mL) by dissolving 1 g of chloroauric acid in 50 mL of ultrapure water. Prepare a 0.1 mol / L sodium borohydride solution (freshly prepared) and a 0.04 mol / L trisodium citrate solution. In a 250 mL flask, add 100 mL of ultrapure water, then add 0.7 mL of the chloroauric acid solution and 1 mL of the trisodium citrate solution. After stirring at room temperature until homogeneous, quickly add 4 mL of the freshly prepared sodium borohydride solution. Stir rapidly until homogeneous, then reduce the stirring speed (800 rpm) and continue the reaction at room temperature for 30 min to obtain a 15 nm gold nanoparticle seed dispersion. Place 1 mL of the AuNPs seed dispersion in a 100 mL Erlenmeyer flask on an ice bath, dilute with ultrapure water to 30 mL, add 0.225 mL of 1% ascorbic acid as a reducing agent, and add 0.03 mL of sodium citrate as a protective agent. Stir rapidly until homogeneous, then add 0.15 mL of the solution to a round-bottom flask. The HAuCl4 solution changed color from wine red to purplish red. After continuous stirring for 30 min, AuNPs sol with a concentration of 200 mg / mL was obtained, and the gold nanoparticles had a particle size of 70~90 nm. Take 200 μL of PDDA-Ti3C2T x The dispersion (concentration of 2 mg / mL) was added dropwise to a 1.5 cm depth. 2 A square glass fiber filter paper with a rough surface was vacuum dried. 200 μL of AuNPs sol (200 mg / mL) was added dropwise to the surface of the glass fiber filter paper in three portions. The loading of gold nanoparticles on the modified substrate was 26.66 mg / cm². 2 Vacuum drying yielded mesoporous Ti3C2T modified with nano-gold. x Materials (PDDA-AuNPs / Mesoporous Ti3C2T) x ).

[0054] Structural characterization

[0055] Figure 2 Example 1: Intermediate Hole Ti3C2T x Electron microscopy characterization of materials ( Figure 2In the image, A is a transmission electron microscope image of the MXene material after mesoporosis, showing the pore structure on the surface of the two-dimensional MXene material film. B is a high-resolution transmission electron microscope image of the MXene after mesoporosis modification, showing the crystal structure, which confirms the existence of mesopores and the structure of the MXene material around the mesopores. C is an atomic force microscope image, confirming that the thickness of the material is 2.1 nm, which is an ultrathin two-dimensional material.

[0056] Figure 3 The images shown are transmission electron microscope images (A) and particle size distribution diagrams (B) of the AuNPs material in Example 1, both of which confirm that the particle size of the AuNPs material is approximately 80 nm.

[0057] Figure 4 Example 1: Intermediate Hole Ti3C2T x Nitrogen desorption characterization diagram of the material ( Figure 4 In the diagram, A represents the intermediate hole Ti3C2T in Example 1. x Material specific surface area; B represents the mesopore Ti3C2T of Example 1. x Nitrogen desorption cycle diagram of the material; C represents mesoporous Ti3C2T from Example 1. x Aperture distribution diagram); by Figure 4 It can be seen that the material obtained a larger specific surface area after mesoporous modification (A), and the material pores are conical or cylindrical (B), with a pore size range of 5-50 nm, which belongs to the mesoporous structure.

[0058] Test Example 1

[0059] Different concentrations (10 ng / mL, 50 ng / mL, 100 ng / mL, 500 ng / mL, 1 μg / mL, 5 μg / mL, 10 μg / mL, 50 μg / mL, 100 μg / mL) of methylene blue aqueous solution were added dropwise to the PDDA-AuNPs / mesoporous Ti3C2T prepared in Example 1. x The material surface was characterized using confocal Raman microscopy to confirm the SERS-enhancing effect of the material. Repeatability testing and mapping scans using confocal Raman microscopy confirmed the material's stability and homogeneity. A comparison was made with AuNPs substrates prepared without PDDA (the PDDA modification step was omitted compared to Example 1).

[0060] Figure 5 For example 1, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity verification diagram of the substrate ( Figure 5In the diagram, A represents the theoretical Raman spectrum of methylene blue and the SERS spectrum of the AuNPs substrate in Test Example 1. PDDA-AuNPs / mesoporous Ti3C2T x B is the SERS spectrum of the substrate; C is the SERS spectrum of methylene blue in Test Example 1 using smooth and rough surfaces; D is the SERS spectrum of methylene blue at a concentration of 10 ng / mL in Test Example 1 on PDDA-AuNPs / mesoporous Ti3C2T. x SERS spectra of the substrate and AuNPs substrate; D represents the PDDA-AuNPs / mesoporous Ti3C2T prepared using different amounts of AuNPs in Test Example 1. x SERS intensity of the substrate; by Figure 5 As shown in Figure A, during SERS analysis of methylene blue, the paper-based AuNPs / Ti3C2T... x The SERS spectrum obtained from the AuNPs sol system is close to that calculated using density functional theory (DFT) of the beacon molecular theory. Comparison with the SERS responses in AuNPs sol and smooth glass fiber filter paper confirms the effectiveness of the matte paper-based AuNPs / MesoTi3C2T system. x The SERS sensitization effect is best when using a low concentration of 10 ng / mL methylene blue, taking the strongest characteristic peak (1624 cm⁻¹) as an example. -1 Paper-based AuNPs / Ti3C2T x The sensitivity of the AuNPs sol system is significantly better than that of the SERS system. Figure 5 (C). Furthermore, the dosage of AuNPs was optimized based on methylene blue, with good results observed at 200 μL of AuNPs, and the increasing trend slowed down with increasing dosage. Figure 5 (D).

[0061] Figure 6 In the text, A represents PDDA-AuNPs / mesoporous Ti3C2T in Test Example 1. x Concentration-response relationship analysis of the substrate to different concentrations of methylene blue; Figure 6 (Figure B is the stability analysis in Test Example 1), indicating that the material can be used to effectively detect methylene blue at concentrations of 10 ng / mL to 100 μg / mL.

[0062] Figure 7 For example 1, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity uniformity diagram of the substrate ( Figure 7 In the diagram, A is the SERS spectrum of the AuNPs substrate prepared without PDDA in Test Example 1; B is the SERS spectrum of the PDDA-AuNPs / mesoporous Ti3C2T substrate prepared using PDDA with a molecular weight of 100k-200k in Test Example 1.x SERS spectrum of the substrate; C represents PDDA-AuNPs / mesoporous Ti3C2T prepared using PDDA with a molecular weight of 100k-200k in Test Example 1. x SERS spectrum of the substrate); three points were selected to analyze the homogeneity and stability of the substrate, and the four Raman shifts with higher Raman responses (1185 cm⁻¹) were compared. -1 1400 cm -1 1502 cm -1 1624cm -1 Raman Peak at ( ) Figure 7 (A~C). Without using PDDA-mesoporous Ti3C2T x When AuNPs are directly added to the surface of glass fiber filter paper, it is visibly observed that due to the "coffee ring" effect, the AuNPs cannot be uniformly distributed on the filter paper surface. Using Ti3C2Tx modified with PDDA of 400k-500k molecular weight can partially stabilize the AuNPs on the filter paper surface, but its RSD is still much greater than 15% (the RSDs of the four characteristic peaks are 36.7%, 43.8%, 50.2%, and 38.9% respectively). Using Ti3C2Tx modified with PDDA of 100k-200k molecular weight... x AuNPs can be more stably crosslinked onto the filter paper surface. After evaluating the RSD of each peak response, the RSD of the Raman response at the four characteristic peaks is less than 15%, which confirms the uniformity of the material.

[0063] A 1624 cm sample was taken under a 50x objective lens. -1 A mapping diagram of the material was plotted based on the Raman response, with 100 points taken from the Y-axis (-20 μm to 20 μm) and X-axis (-20 μm to 20 μm). This confirmed the stability and uniformity of the paper-based PDDA-AuNPs / MesoTi3C2Tx, as shown in the figure. Figure 8 .

[0064] Figure 8 In the text, A represents PDDA-AuNPs / mesoporous Ti3C2T in Test Example 1. x SERS spectrum of 100 methylene blue on the substrate; B test example 1 PDDA-AuNPs / mesoporous Ti3C2T x SERS mapping of the substrate with 100 methylene blue stains; PDDA-AuNPs / mesoporous Ti3C2T in C test example 1 x SERS mapping histograms of the substrate with 100 methylene blue; confirming the use of PDDA-AuNPs / mesoporous Ti3C2T prepared with PDDA of molecular weight 100k-200k. xThe SERS signal deviation on the same substrate is less than 15%, which shows good uniformity.

[0065] Test Example 2

[0066] Establish a standard curve for ciprofloxacin using a blank matrix: Prepare 10 mL of ciprofloxacin standard solutions of 20 ng / mL, 50 ng / mL, 100 ng / mL, 200 ng / mL, 500 ng / mL, 20 μg / mL, 50 μg / mL, 70 μg / mL, 150 μg / mL, and 200 μg / mL using deionized water for later use.

[0067] Mix 200 μL of the aqueous solution of the sample to be tested with 200 μL of 1 M NaCl solution, and add the mixture dropwise to the PDDA-AuNPs / mesoporous Ti3C2T solution prepared in Example 1. x The surface is inspected and the results are recorded.

[0068] Milk was selected as the test sample for determining ciprofloxacin. After simple processing, the test sample was directly added dropwise to PDDA-AuNPs / mesoporous Ti3C2T. x The determination was performed on the surface. The optimized conditions were as follows: 1 mL of milk sample was added to 2 mL of ethyl acetate to extract ciprofloxacin from the milk. After centrifugation, 1.2 mL of the supernatant was collected. The extract was treated with 50 mg PSA and 100 mg MgSO4 as extraction solvents, dried under nitrogen, and reconstituted in 600 μL of deionized water. 200 μL of the test liquid was mixed with 200 μL of NaCl (1 mol / L) solution and then added dropwise to the PDDA-AuNPs / mesoporous Ti3C2T prepared in Example 1. x Raman spectroscopy was used to detect it. PDDA-mesoporous Ti3C2T was employed. x (No nano-gold added compared to Example 1), mesoporous Ti3C2T x A comparison was made with a substrate (without PDDA and gold nanoparticles compared to Example 1).

[0069] Confocal micro Raman spectrometer instrument parameters: excitation wavelength 785 nm, power filter 100%, integration time 30 s, grating 600 (750 nm), 10x optical objective lens, each sample scanned three times, and the results recorded.

[0070] Figure 9 In Test Example 2, PDDA-AuNPs / mesoporous Ti3C2T was used. x PDDA-mesoporous Ti3C2T x Mesoporous Ti3C2T x SERS spectrum of ciprofloxacin at the base stage; Figure 9 In test example B, PDDA-AuNPs / mesoporous Ti3C2T is used. x Concentration-response relationship analysis of the substrate to different concentrations of ciprofloxacin. Figure 9 C in the middle represents the use of PDDA-AuNPs / mesoporous Ti3C2T x Concentration-response linear relationship graph when detecting ciprofloxacin standard on substrate. The paper-based PDDA-AuNPs / mesoporous Ti3C2T prepared in Example 1 was used. x For the detection of ciprofloxacin, its Raman response signal is significantly superior to that based on blank paper and PDDA-mesoporous Ti3C2T. x Raman response of paper-based ( Figure 9 The results were compared with the theoretical Raman spectra obtained from density functional theory calculations to identify the full peak shift. A linear standard curve (Y=116X+3780) was prepared for ciprofloxacin at concentrations of 50 ng / mL-70 μg / mL. 2 The value is 0.9893 ( Figure 9 (C)

[0071] Figure 10 For example 2, PDDA-AuNPs / mesoporous Ti3C2T were used. x SERS spectrum of ciprofloxacin as a base ( Figure 10 In the diagram, A represents the theoretical Raman spectrum of ciprofloxacin in test example 2, and PDDA-AuNPs / mesoporous Ti3C2T. x SERS spectrum of the substrate; BC represents PDDA-AuNPs / mesoporous Ti3C2T prepared using PDDA in Test Example 2. x SERS spectra (B) and first derivative plots (C) of ciprofloxacin, enrofloxacin, norfloxacin, and enoxacin on the substrate; D is the SERS spectrum (B) of PDDA-AuNPs / mesoporous Ti3C2T used in test example 2. x Principal component analysis plots of SERS spectra of ciprofloxacin, enrofloxacin, norfloxacin, and enoxacin at the base stage. The theoretical Raman characteristic peaks of ciprofloxacin obtained from density functional theory calculations include the peak at 760 cm⁻¹. -1 1042 cm -1 1207 cm -1 1282 cm -1 1390 cm -1 1657 cm -1 1042 cm -1 Corresponding to pyrazine ring vibration, 1207 cm -1 Corresponding to CN key vibration, 1282 cm -1 Corresponding to CF vibration, 1390 cm -1Corresponding to OCO and pyrazine ring vibrations, 1657 cm -1 Corresponding to CC vibration. The theoretically calculated Raman peak corresponding to the actual measured peak includes 785 cm. -1 1068 cm -1 1190 cm -1 1300 cm -1 1385 cm -1 1627 cm -1 The Raman shifts in between are caused by AuNPs / Ti3C2T x (caused by external forces) Figure 10 (A)

[0072] Figure 11 In Test Example 2, PDDA-AuNPs / mesoporous Ti3C2T was used. x A graph showing the intraday stability analysis of ciprofloxacin determined at the base time. Figure 11 In Test Example 2, PDDA-AuNPs / mesoporous Ti3C2T were used. x The intraday stability analysis of ciprofloxacin determined at substrate temperature indicates that the material has good stability, achieving good stability under repeated use and continuous use for 7 days, providing the necessary conditions for the practical application of the material.

[0073] Figure 12 For example 2, PDDA-AuNPs / mesoporous Ti3C2T x SERS activity uniformity diagram of the substrate ( Figure 12 In the diagram, A represents the PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x SERS spectra of ciprofloxacin extracted from milk using different solvents in the substrate; B is the SERS spectrum of PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x The SERS response intensity of the substrate using different purifiers; C represents the SERS response intensity of PDDA-AuNPs / mesoporous Ti3C2T used in Test Example 2. x SERS spectrum of the substrate; D represents PDDA-AuNPs / mesoporous Ti3C2T in test example 2. x (Base determination: SERS concentration-response relationship of ciprofloxacin in milk).

[0074] In milk and other food products, the complex matrix can significantly affect the final Raman spectrum if the matrix is ​​not properly purified. QuEChERS is an effective method for removing sterols, proteins, organic acids, pigments, etc., from the sample matrix. When detecting ciprofloxacin in milk samples, acetonitrile, methanol, and ethyl acetate were used for extraction and protein precipitation. The Raman spectra after these treatments were compared to select the optimal extraction reagent. The Raman spectrum obtained after extraction with ethyl acetate and nitrogen drying, followed by reconstitution with water, showed the most prominent peak shape. Figure 12 (A)

[0075] Four different purification agents (No-C) were used respectively. 18 : GCB, PSA, MgSO4 100 mg each; No-GCB: C 18 100 mg each of PSA and MgSO4; No-PSA: C 18 , GCB, MgSO4 100 mg each; No-MgSO4: C 18 GCB and PSA 100 mg each; All: C 18 Milk samples spiked with ciprofloxacin were treated with 100 mg each of GCB, PSA, and MgSO4. The mixture was then vortexed with milk containing the target analyte, centrifuged for 30 seconds, and the supernatant was collected. This confirmed that the recovery of ciprofloxacin was optimal in the absence of GCB. (Removing C...) 18 The subsequent removal of PSA or anhydrous magnesium sulfate had little impact on the purification effect. However, the removal of PSA or anhydrous magnesium sulfate alone had the greatest impact. This is because PSA can effectively remove organic acids and fatty acids in the sample matrix, but excessive PSA may adsorb target analytes such as ciprofloxacin. The Raman spectrum obtained after treatment with 50 mg PSA and 100 mg anhydrous magnesium sulfate, determined by experimental optimization, was the most significant. Figure 12 (BC). In summary, ethyl acetate was used to extract ciprofloxacin from the milk sample, and PSA and anhydrous magnesium sulfate were used to purify the sample. After drying with nitrogen, the sample was reconstituted with pure water. The Raman spectrum collected at this time was the most significant.

[0076] The above processing method was used to detect ciprofloxacin in the simulated sample. Figure 12 In the middle D, with the increase of ciprofloxacin concentration, 1390 cm -1 The Raman response at the concentration increased, and a good linear relationship was observed in the range of 20 ng / mL to 500 ng / mL (R0). 2 =0.9171), the LODs of the sample obtained by three times the signal-to-noise ratio (S / N) was 27.4 ng / mL. The recovery rate was verified by three sets of simulated sample pairs and was between 85% and 115%, which is relatively stable.

[0077] Furthermore, by combining the Raman response and dose dependence observed in actual measurements, the characteristic peak of ciprofloxacin was further determined to include 785 cm⁻¹. -1 831 cm -1 942 cm -1 1068 cm -1 1300 cm -1 1344 cm -1 1385 cm -1 1455cm -1 1627 cm -1 The concentration and Raman response of the above characteristic peaks were fitted to the theoretical Raman peaks of ciprofloxacin obtained by density functional theory calculations. The best linear relationship was found at 1385 cm⁻¹. -1 The Raman peak at [location missing] was observed. A standard curve was plotted using ciprofloxacin at concentrations ranging from 50 ng / mL to 200 μg / mL. After logarithmic transformation, the fitted R-value was 0.93. Figure 13 ).

[0078] Figure 14 PDDA-AuNPs / mesoporous Ti3C2T in Example 1 x SERS enhancement mechanism diagram of substrate ( Figure 14 In the diagram, A represents the SERS spectrum of the AuNPs substrate prepared without PDDA; B represents the PDDA-AuNPs / mesoporous Ti3C2T substrate from Example 1. x SERS spectrum of the substrate; C represents PDDA-AuNPs / mesoporous Ti3C2T in Example 1. x SERS spectrum of the substrate; D represents the mesoporous Ti3C2T substrate of Example 1. x 3D structural diagram of the substrate; E represents the intermediate hole Ti3C2T in Example 1. x Density state distribution diagram of the substrate; F represents the mesopore Ti3C2T in Example 1. x (Electron transfer between the substrate and ciprofloxacin molecules). Figure 14 It can be proven that mesoporous Ti3C2T x The substrate possesses valence and conduction band energy levels close to the highest occupied and lowest unoccupied molecular orbitals of the ciprofloxacin molecule, enabling electronic transitions under 785 nm laser irradiation. These electronic transitions further enhance the chemical enhancement of surface-enhanced Raman scattering (SERS), thereby improving the activity of SERS.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nano-gold modified mesoporous MXene material, characterized in that, Includes the following steps: Ti3C2T x The material is dispersed in water, and the resulting Ti3C2T x The dispersion was mixed with copper salt solution and hydrogen peroxide solution to carry out an oxidation reaction. The resulting product was mixed with hydrofluoric acid and etched to obtain mesoporous Ti3C2T. x Material; The mesoporous Ti3C2T x The material was mixed with polydiallyldimethylammonium chloride and water to undergo a crosslinking reaction, yielding PDDA-modified Ti3C2T. x ; Modify Ti3C2T with PDDA x It adheres to the substrate surface to obtain a modified substrate; By attaching gold nanoparticles to a modified substrate, a gold nanoparticle-modified mesoporous MXene material is obtained.

2. The preparation method according to claim 1, characterized in that, The concentration of the copper salt solution is 0.5~2 mol / L, the mass concentration of the hydrogen peroxide solution is 10~50%, and the volume ratio of the copper salt solution to the hydrogen peroxide solution is 100~200:50~100. The Ti3C2T x The concentration of the dispersion is 2~6 mg / mL, and the Ti3C2T x The volume ratio of the dispersion to the copper salt solution is (10~30)×10. 3 65~85.

3. The preparation method according to claim 1 or 2, characterized in that, The oxidation reaction is carried out at a temperature of 40-45°C for a time of 15-45 minutes. The mesoporous Ti3C2T x The material has a pore size of 2~50 nm.

4. The preparation method according to claim 1, characterized in that, The molecular weight of the polydiallyl dimethyl ammonium chloride is 100-200k, and the mesoporous Ti3C2T x The mass ratio of the material to polydiallyldimethylammonium chloride is 1:20~30.

5. The preparation method according to claim 1 or 4, characterized in that, The cross-linking reaction is carried out at a temperature of 30-40°C for 5-7 hours.

6. The preparation method according to claim 1, characterized in that, The gold nanoparticles in the gold nanoparticle sol are prepared by growth synthesis; the particle size of the gold nanoparticles is 70~90 nm.

7. The preparation method according to claim 6, characterized in that, The PDDA-modified Ti3C2T x The mass ratio of the nanoparticles to gold nanoparticles is 0 to 5:100 and is not 0.

8. The preparation method according to claim 7, characterized in that, The loading amount of the gold nanoparticles on the modified substrate is 2~100 mg / cm³. 2 .

9. The nano-gold modified mesoporous MXene material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the nano-gold modified mesoporous MXene material of claim 9 in the detection of quinolone antibiotics using surface-enhanced Raman spectroscopy.

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