Application of multidimensional plasma coupling system based on Ag-coated PVP and Au-coated Ag NCs to surface enhanced Raman spectroscopy (SERS) detection of gentamicin

Abstract

A multidimensional plasma coupling system based on Ag-coated PVP and Au-coated Ag NCs is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, relates to the field of analysis and detection, and adopts hydrothermal synthesis to prepare Ag-coated PVP core-shell nanoparticles and Au-coated Ag core-shell cubes (Au-coated Ag NCs). Ag-coated PVP is induced to agglomerate through gentamicin, then Au-coated Ag NCs is introduced to change an electromagnetic field of nanoparticle agglomeration, a Raman characteristic peak of gentamicin is changed, and gentamicin is distinguished from a homologue of gentamicin. Under optimized experimental conditions, the linear detection range of gentamicin is 10 <-5 >-10 <-9 > M, the detection limit is 6.23 * 10 <-10 > M, and the relative standard deviation of SERS intensity is less than 10%. The method is simple and convenient to operate and high in accuracy and sensitivity, does not need a complicated operation technology, and meets the requirements of large-batch and rapid analysis and detection.

Description

Technical Field

[0001] The present invention relates to the field of analysis and detection, and in particular to a multi-dimensional plasma coupling system based on Ag@PVP and Au@Ag NCs for surface enhanced Raman spectroscopy (SERS) detection of gentamicin. Background Art

[0002] Gentamicin (Gen) is an aminoglycoside antibiotic. Due to its molecular structure with a large number of positive charges, it exists in the form of original drug after entering the body and is difficult to be metabolized and degraded. Its main excretion route is through the kidneys, but a small part is still enriched in the epithelial cells of the proximal tubules of the kidneys. This enrichment can damage kidney function and slow down the excretion of drugs, thus forming a vicious circle. Since the drug in the body cannot be effectively excreted, renal toxicity is produced, which further induces ototoxicity, which may cause neurological damage such as dizziness, nausea and nystagmus. In severe cases, allergic reactions such as shock, rash, etc. may occur, and even cause death. Therefore, in order to ensure food safety, GB 31650-2019 "National Food Safety Standard Maximum Residue Limits of Veterinary Drugs in Food" stipulates that the maximum residue limit of gentamicin in animal food is 200 μg / kg. Therefore, it is particularly important to develop a highly sensitive and selective detection method for gentamicin drug residues. However, achieving this goal faces great challenges, mainly due to the fact that gentamicin lacks a chromophore or fluorophore and requires derivatization.

[0003] At present, the detection methods of gentamicin mainly include high performance liquid chromatography, fluorescent immunoassay, ultraviolet spectrophotometry, liquid chromatography-mass spectrometry and microbiological methods. The columns in high performance liquid chromatography have extremely high requirements for sample pretreatment, consume a large amount of liquid and reagent consumables, and are easy to clog the columns and cause economic losses; the fluorescence detection method requires pre-derivation treatment, which is cumbersome and time-consuming, and incomplete derivatization reaction will also reduce the sensitivity of the detection; compared with ultraviolet and fluorescence detection, liquid chromatography-mass spectrometry is more convenient, does not require derivatization steps, and has significantly higher sensitivity than microbiological methods, but it has high requirements for the professional skills of operators and the equipment cost is also expensive, so it is not suitable for rapid screening and promotion of large quantities of samples. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems in the prior art and provide a simple, rapid and reliable SERS detection method for gentamicin. Ag@PVP and Au@Ag NCs are prepared as SERS substrates to perform quantitative analysis of gentamicin. Under the conditions of optimized volume ratio and pH, qualitative and quantitative analysis of gentamicin is achieved. The linear detection range of gentamicin is 10 -5 ~10 -9M, the detection limit was 6.23 × 10 -10 The relative standard deviation of SERS intensity is less than 10%. This method has the advantages of low cost, controllability, high detection efficiency, etc., and is easy to operate, high in accuracy and sensitivity, does not require complex operation techniques, can meet the requirements of large-scale and rapid analysis and detection, and can be promoted and applied.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] The multidimensional plasmon coupling system based on Ag@PVP and Au@Ag NCs was used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, including the following steps:

[0007] 1) Preparation of Ag@PVP core-shell nanoparticles;

[0008] 2) Preparation of Au@Ag NCs sol;

[0009] 3) The gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles, and then Au@Ag NCs sol was added to distinguish gentamicin from other homologues through the Raman characteristic peaks of gentamicin;

[0010] 4) Quantitative analysis and detection of gentamicin.

[0011] In step 1), a sodium citrate reduction method is used to prepare a silver sol, and then PVP is added to the silver sol to obtain the Ag@PVP core-shell nanoparticles.

[0012] In step 2), a gold seed solution and a growth solution are synthesized separately, the two solutions are mixed and allowed to stand to obtain a gold growth solution, the gold growth solution is then reacted with a CTAC solution, and then a silver nitrate solution and an ascorbic acid-CTAC solution are simultaneously injected to obtain the Au@Ag NCs sol.

[0013] The gentamicin sample solution was mixed with the Ag@PVP core-shell nanoparticles to allow gentamicin to induce the aggregation of Ag@PVP. The gentamicin -1 After the addition of Au@Ag NCs sol, Au@Ag NCs regulated the surface plasma of Ag@PVP, causing the Raman characteristic peak of gentamicin to shift from 948 cm -1 The displacement is 786 cm -1 .

[0014] The distinction between gentamicin and other homologues refers to the Raman characteristic peak position of gentamicin appearing at 786 cm -1 , other homologues did not appear.

[0015] Such other homologs include netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin.

[0016] As the concentration of the gentamicin sample solution increases, the intensity of the SERS characteristic peak of gentamicin will increase. A standard curve is established using the relationship between the intensity of the SERS characteristic peak of gentamicin and the concentration to perform quantitative analysis and detection on the gentamicin solution.

[0017] The linear detection range of gentamicin is 10 -5 ~10 -9 M, the detection limit was 6.23 × 10 -10 M, the relative standard deviation of SERS intensity is less than 10%.

[0018] The pH of the gentamicin sample solution after being mixed with the Ag@PVP core-shell nanoparticles and the Au@Ag NCs sol for SERS detection is 5-6.

[0019] The gentamicin sample solution is mixed with the Ag@PVP core-shell nanoparticles and the Au@Ag NCs sol for reaction within 10 s for SERS detection.

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0021] The present invention uses Ag@PVP and Au@Ag NCs as SERS substrates. The substrate not only has excellent SERS Raman enhancement effect, but also excellent stability and sensitivity. At the same time, the preparation process is simple, the cost is low, the repeatability is high, the detection sensitivity is excellent, and the detection method is simple and easy to operate. The experimental results show that the linear detection range of gentamicin is 10 -5 ~10 -9 M, the detection limit was 6.23 × 10 -10 M, its value is lower than the prescribed residue limit of gentamicin in animal food (200 μg / kg), and the relative standard deviation of SERS intensity is less than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A in the middle is the SEM image of Ag@PVP core-shell nanoparticles; Figure 1 B is the SEM image of Au@Ag NCs; Figure 1 C is the TEM image of Au@Ag NCs; Figure 1 D in the figure is the TEM image of Ag@PVP core-shell nanoparticles.

[0023] Figure 2 a is Ag@PVP and 10 -5M is the plasma resonance spectrum of gentamicin after mixing; b is the plasma resonance spectrum of Au@Ag NCs added to Ag@PVP and 10 -5 Plasmon resonance spectrum of the mixed solution of M-gentamicin.

[0024] Figure 3 This is the SERS spectrum of the Ag@PVP-Gen-Au@Ag NCs system.

[0025] Figure 4 For Ag@PVP and 10 -5 SERS spectra of M gentamicin mixed in different volume ratios.

[0026] Figure 5 A in the middle is the SERS spectra of the Ag@PVP-Gen-Au@Ag NCs system mixed in different volume ratios; Figure 5 B in the figure is the SERS spectrum of gentamicin under different pH conditions.

[0027] Figure 6 A in the middle is the SERS spectra of gentamicin under different reaction times, from top to bottom a→f are (a) 5s, (b) 10s, (c) 40s, (d) 60s, (e) 80s, (f) 100s; Figure 6 B is the peak of gentamicin at 786 cm at different reaction times -1 Line graph of characteristic peaks.

[0028] Figure 7 A in the figure is the Ag@PVP-Gen-Au@Ag NCs system measuring gentamicin ten times in parallel (10 -5 M) SERS spectrum; Figure 7 B is a parallel measurement of gentamicin (10 -5 M) at 786 cm -1 Histogram of SERS peak intensity at .

[0029] Figure 8 A in the figure is the SERS spectra of gentamicin at different concentrations, where the concentration from top to bottom a→e is (a) 10 -5 M (b) 10 -6 M (c) 10 -7 M (d) 10 -8 M (e) 10 -9 M; Figure 8 B is gentamicin at 786 cm -1 The relationship between the SERS intensity at and the negative logarithm of the concentration.

[0030] Fig. 9The SERS spectra of different aminoglycoside antibiotic solutions mixed with Ag@PVP sol, from top to bottom are gentamicin, sisomicin, streptomycin, kanamycin, netilmicin, tobramycin, amikacin and neomycin.

[0031] Fig.10 A in the middle is the SERS spectra of different aminoglycoside antibiotic solutions, from top to bottom, gentamicin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin; Fig.10 B is the Raman characteristic peak of gentamicin and other aminoglycoside antibiotics at 786 cm -1 A bar chart showing the comparison. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0033] The present invention sequentially mixes gentamicin solutions of different concentrations with Ag@PVP and Au@Ag NCs according to an optimal volume ratio, adjusts the mixed solution to an optimal pH value, excites with a suitable excitation wavelength, performs surface enhanced Raman detection, and collects SERS spectra within an optimal reaction time. As the concentration of gentamicin increases, the intensity of its SERS characteristic peak increases. A standard curve is established using the relationship between the intensity and concentration of the SERS characteristic peak of gentamicin to perform quantitative analysis and detection of the gentamicin solution. Gentamycin is used at 786 cm -1 The Raman characteristic peak at 786 cm is used for qualitative analysis and detection. The suitable excitation wavelength refers to the 785 nm excitation wavelength; the SERS characteristic peak of gentamicin at a specific wavelength is gentamicin at 786 cm -1 The SERS characteristic peak at .

[0034] The present invention comprises the following steps:

[0035] 1) Preparation of Ag@PVP core-shell nanoparticles;

[0036] 2) Preparation of Au@Ag NCs sol;

[0037] 3) The gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles, and then Au@Ag NCs sol was added to distinguish gentamicin from other homologues through the Raman characteristic peaks of gentamicin;

[0038] 4) Quantitative analysis and detection of gentamicin.

[0039] In step 1), the mass percentage concentration of the sodium citrate is 0.8% to 1.5%, the volume ratio of sodium citrate to silver nitrate is 30 to 50, and the concentration of the silver nitrate solution is 1 to 5 mM; the reaction temperature is 90 to 100 °C, the reaction time is 50 to 60 min, and the stirring speed is 1000 to 1500 r / min; the Ag nanoparticles are spherical Ag nanoparticle sols with a particle size of about 50 nm. The mass concentration of the PVP solution is 1% to 4%, the volume of the PVP solution is 40 to 50 μL; the stirring speed is 900 to 1200 r / min, and the reaction time is 20 to 30 min; the Ag@PVP is a spherical Ag@PVP core-shell nanoparticle with a particle size of about 52.48 ± 10.34 nm.

[0040] In step 2), the concentration of the HAuCl4 solution used in the first step of preparing Au@Ag NCs sol by the seed-mediated method is 0.5-0.6 mM, the concentration of the cetyltrimethylammonium bromide (CTAB) solution is 200-250 mM, the concentration of the NaBH4 solution is 10-20 mM, the concentration of the CTAC solution is 200-250 mM, and the concentration of the ascorbic acid solution is 100-150 mM; the reaction temperature is 25-27 ° C, and the stirring speed is 1000-1500 r / min. The concentration of the CTAC solution used in the second step of preparing the Au@Ag NCs sol by the seed-mediated method is 20-25 mM, and the concentration of the silver nitrate solution is 2-5 mM; the concentration of the ascorbic acid solution in the ascorbic acid-CTAC solution is 50-60 mM, and the concentration of the CTAC solution is 40-50 mM; the reaction temperature is 60-70 ° C, and the stirring speed is 1000-1500 r / min; the Au@Ag NCs are square Au@Ag NCs nanoparticles with a particle size of approximately 73.03 ± 10.26 nm.

[0041] Specific examples are given below.

[0042] 1) Synthesis of Ag@PVP core-shell nanoparticles

[0043] Synthesis of silver sol. Take 100 mL of silver nitrate solution in a single-mouth round-bottom flask, heat it with an electric heating mantle, and heat it to boiling reflux under magnetic stirring. Rapidly add sodium citrate solution. The solution changes from colorless to milky white in about 1 minute. Continue heating and reflux for 50 to 60 minutes. After the solution changes from milky white to yellow-green, remove the heating mantle and stop heating. Cool it naturally to room temperature, cover the round-bottom flask with aluminum foil, seal it, and store it away from light.

[0044] Specifically, in this embodiment, the mass percentage concentration of the sodium citrate is 0.8%, the volume ratio of sodium citrate to silver nitrate is 30, and the concentration of the silver nitrate solution is 1 mM.

[0045] Synthesis of Ag@PVP core-shell nanoparticles. Take 40 mL of the prepared silver sol in a 100 mL round-bottom flask, add 40 μL of 1% PVP solution, and react for 20 min at room temperature and a magnetic stirring speed of 1000 r / min to obtain Ag@PVP core-shell nanoparticles with a shell thickness of about 3 to 5 nm. The particle size, shape and shell thickness of the core-shell nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and stored at 4 °C in the dark.

[0046] 2) Synthesis of Au@Ag NCs sol

[0047] The specific method is divided into two steps. In the first step, the mixture of HAuCl4 (5 mL, 0.5 mM) solution and CTAB (5 mL, 200 mM) solution was stirred at room temperature for 30 min, and then the frozen NaBH4 (0.6 mL, 10 mM) solution was added to the 10 mL aqueous solution containing HAuCl4 and CTAB to prepare a brown seed solution, and then the seed solution was stirred at room temperature in the dark for 3 h (reaction temperature was 25-27 ° C, stirring speed was 1000-1500 r / min). Secondly, HAuCl4 (20 mL, 0.5 mM) solution, CTAC (20 mL, 200 mM) solution and ascorbic acid (15 mL, 100 mM) solution were mixed. The mixed solution was stirred in a water bath at room temperature (water bath temperature was 25-27°C) for 30 min to prepare a growth solution. The prepared seed solution was added to the above growth solution, gently mixed for 30 s, and then stirred at room temperature for 15 min. The stirred solution was allowed to stand for 30 min.

[0048] In the second step, 3.5 mL of the above-mentioned static solution and 48.25 mL of CTAC (20 mM) solution were mixed in a 100 mL glass bottle, and heated with magnetic stirring in a 60 °C water bath for 20 min. Then, 50 mL of AgNO3 (2 mM) solution and 50 mL of ascorbic acid-CTAC solution (containing 50 mM ascorbic acid solution and 40 mM CTAC solution, 25 mL each) were injected into the above solution at a rate of 0.2 mL / min using a syringe pump. Then, the mixture was reacted in a 60 °C water bath for 4 h. The reaction mixture changed from red to brown-yellow. Finally, the glass bottle was placed in an ice water bath for cooling. The synthesized Au@Ag NCs were stored at 4 °C.

[0049] Figure 1 A is the SEM image of the prepared Ag@PVP core-shell nanoparticles. Figure 1 B is the SEM image of the prepared Au@Ag NCs. Figure 1 C is the TEM image of the prepared Au@Ag NCs. Figure 1 D in the figure is the TEM image of the prepared Ag@PVP core-shell nanoparticles. Figure 1 It can be seen in A and D that the Ag nanoparticles are surrounded by a relatively uniform PVP shell layer, the shell thickness is about 3-5 nm, and the particle size of the Ag@PVP core-shell nanoparticles is about 52.48 ± 10.34 nm; Figure 1 B and C in the figure are the final products of synthesized silver cubes, Au@Ag NCs. It can be seen from the figure that their size and uniformity are good, and the particle size is about 73.03 ± 10.26nm.

[0050] 3) UV characterization of Ag@PVP-Gen-Au@Ag NCs detection system

[0051] The Ag@PVP-Gen-Au@Ag NCs detection system was characterized by UV. Figure 2 a is Ag@PVP and 10 -5 M is the plasma resonance spectrum of gentamicin after mixing; b is the plasma resonance spectrum of Au@Ag NCs added to Ag@PVP and 10 -5 Plasmon resonance spectrum of gentamicin mixed solution. Figure 2 As shown in Figure a, when gentamicin is added, the absorption spectrum of Ag@PVP changes significantly, and a new plasma resonance absorption peak appears at ~772 nm. This phenomenon indicates that there is an electrostatic interaction between the positively charged amino groups in the gentamicin molecules and the negatively charged Ag@PVP nanoparticles, which induces the nanoparticles to agglomerate and form aggregated nanostructures, causing the new surface plasmon resonance absorption peak to move to a longer wavelength, resulting in an obvious red shift.

[0052] When Ag@PVP and 10 -5 After Au@Ag NCs were added to the mixed solution of M gentamicin, Figure 2 In the plasma resonance spectrum of (b), multiple absorption peaks appeared, located at 348 nm, 398 nm, 451 nm, 503 nm and 735 nm, respectively. The appearance of these peaks indicated that after the introduction of Au@Ag NCs, the interaction between Ag@PVP and gentamicin changed. Au@AgNCs regulated the surface plasma of Ag@PVP, resulting in the generation of new plasma resonance modes. Figure 2The peak of a in the graph has changed significantly, especially at lower wavelengths (such as 348 nm and 398 nm), new absorption peaks have appeared. This may be because the addition of Au@Ag NCs has changed the local electronic environment of the detection system, causing the surface plasmon resonance absorption peak to move toward a shorter wavelength, resulting in an obvious blue shift.

[0053] 4) Feasibility of the Ag@PVP-Gen-Au@Ag NCs detection system

[0054] To verify the feasibility of the experiment, Ag@PVP, gentamicin (Gen) and Au@Ag NCs were mixed in sequence and then Raman detection was performed. Figure 3 As shown in Figure A, the Raman spectrum of Au@Ag NCs mixed with gentamicin is a flat line. This may be because there is no interaction between gentamicin and Au@Ag NCs, resulting in the absence of the characteristic peak of gentamicin in the Raman spectrum. -1 The Raman characteristic peak appears at 948 cm-1, which may be due to the agglomeration of Ag@PVP induced by gentamicin. During the agglomeration process, the Raman signal of CH bending vibration is enhanced, making gentamicin -1 When Au@Ag NCs were added to the Ag@PVP and Gen mixture, the Raman characteristic peak shifted to 786 cm -1 The Raman characteristic peaks at the position are significantly enhanced, which enables the identification and distinction of its homologues (see Fig.10 ), which can perform specific SERS detection of gentamicin. This is because when gentamicin induces Ag@PVP aggregation, Au@Ag NCs regulate the surface plasma of Ag@PVP, and the Raman signal of OH stretching vibration is enhanced, which causes the Raman characteristic peak of gentamicin to shift from 948 cm -1 Displacement to 786 cm -1 , confirming the feasibility of the system; the Raman spectrum of Ag@PVP showed no SERS signal, indicating that the substrate has been successfully prepared.

[0055] By adjusting the order of adding Ag@PVP and Au@Ag NCs, it was further verified that after gentamicin induced the aggregation of Ag@PVP, Au@Ag NCs regulated the surface plasma of Ag@PVP, causing the shift of the Raman characteristic peak of gentamicin. Figure 3 As shown in Figure B, Ag@PVP and Au@Ag NCs were mixed first and then gentamicin was added. -1The Raman characteristic peak of Ag@PVP and Au@Ag NCs is obviously weaker. This result shows that the addition order of Ag@PVP and Au@Ag NCs has a certain influence on the detection of gentamicin.

[0056] 5) Optimization of the optimal volume ratio

[0057] The concentration of SERS substrate (Ag@PVP, Au@Ag NCs) was the original solution concentration, and the concentration of gentamicin solution was 10 -5 M. First, Ag@PVP and gentamicin solution were mixed at different volume ratios (1:2, 1:1.5, 1:1, 1:0.5) to determine the optimal volume ratio of Ag@PVP and gentamicin. Figure 4 It can be seen that when the volume ratio of Ag@PVP to gentamicin solution is 1:1, gentamicin induces Ag@PVP to aggregate at 948 cm -1 A strong Raman characteristic peak appeared at

[0058] Subsequently, Au@Ag NCs sol was added to the mixed solution of Ag@PVP and gentamicin, and the volume ratio of Au@Ag NCs to the mixed solution of Ag@PVP and gentamicin was adjusted to 2:1, 1.5:1, 1:1, 0.67:1, and 0.5:1, respectively, and SERS spectra were collected. Figure 5 In Figure A, it can be seen that when the volume ratio of Au@Ag NCs to the mixed solution of Ag@PVP and gentamicin reaches 1:1, Au@AgNCs regulate the surface plasmon of Ag@PVP, making the Raman characteristic peak of gentamicin shift from 948 cm -1 Displacement to 786 cm -1 , which can be distinguished from its homologues. Therefore, in subsequent experiments, the volume ratio of Au@Ag NCs to the mixed solution of Ag@PVP and gentamicin was fixed at 1:1.

[0059] 6) Optimization of optimal pH

[0060] The volume ratio of the mixed solution of Au@Ag NCs, Ag@PVP and gentamicin was fixed at 1:1, and the pH of the mixed solution was adjusted to 2, 4, 5, 6, 8, and 10, respectively. The surface enhanced Raman spectrum of gentamicin was scanned to determine the optimal pH.

[0061] Figure 5 Figure B shows the SERS spectra of gentamicin measured under different pH conditions. As can be seen from the figure, when pH = 5, the intensity of the surface enhanced Raman signal peak of gentamicin is the strongest, and when the pH value is 6, 8 or 10 ( Figure 5 In B, the signal intensity of the Raman characteristic peak decreased significantly. Therefore, the optimal pH value of the gentamicin detection system was fixed at 5.

[0062] 7) Optimization of response time

[0063] The volume ratio of Au@Ag NCs to Ag@PVP and gentamicin mixed solution was fixed at 1:1, the pH value of the mixed solution was 5, and the reaction time was adjusted to 5 s, 10 s, 40 s, 60 s, 80 s, and 100 s, respectively. The SERS spectrum of gentamicin was scanned to determine the optimal reaction time.

[0064] Figure 6 A in the middle is the SERS spectra of gentamicin measured under different reaction time conditions, from top to bottom a→f are (a) 5 s, (b) 10 s, (c) 40 s, (d) 60 s, (e) 80 s, and (f) 100 s. Figure 6 As can be seen from Figure B, the SERS detection effect of gentamicin is best when the reaction time is 0-10 s. Therefore, the optimal reaction time of the gentamicin detection system is within 10 s.

[0065] 8) SERS substrate uniformity detection

[0066] The volume ratio of Au@Ag NCs to Ag@PVP and gentamicin mixed solution was fixed at 1:1, the pH was adjusted to 5, and ten SERS spectra were randomly collected on the substrate at an excitation wavelength of 785 nm. The SERS peak intensities of gentamicin collected ten times in parallel were compared to determine the uniformity of the SERS substrate.

[0067] Figure 7 A in the middle is the SERS spectrum of gentamicin measured ten times in parallel. Figure 7 B is the result of ten parallel measurements of gentamicin at 786 cm -1 The bar graph of the SERS peak intensity at 786 cm is shown in Figure 2. It can be seen that the relative standard deviation (RSD) of the SERS characteristic peak intensity calculated for the 10 groups of parallel samples is -1 It is 3.29% at the bottom, which is less than 10%, indicating that the uniformity of the SERS substrate is good and can be applied to the quantitative analysis of gentamicin by surface enhanced Raman spectroscopy.

[0068] 9) SERS detection of gentamicin

[0069] The volume ratio of Au@Ag NCs to Ag@PVP and gentamicin mixed solution was fixed at 1:1, the pH was controlled at 5, and the SERS spectra were collected under excitation with an excitation light wavelength of 785 nm. The SERS spectra of gentamicin at different concentrations were measured.

[0070] Figure 8 A in the figure is the SERS spectra of gentamicin at different concentrations, where the concentrations of a→e from top to bottom are 10 -5 M, 10-6 M, 10 -7 M, 10 -8 M, 10 -9 M, it can be seen that with the increase of concentration, the surface enhanced Raman peak intensity of gentamicin becomes stronger.

[0071] Figure 8 B is the standard curve established after testing different concentrations of gentamicin standard solutions. -5 ~10 -9 In the range of M, gentamicin 786 cm -1 The intensity of the characteristic peaks showed a negative logarithmic relationship with the concentration of gentamicin, showing a positive correlation (y = 1349.48 x +13468.23), R 2 = 0.9968. In addition, the limit of detection (LOD) was 6.23 × 10 -10 M.

[0072] 10) Selectivity of SERS substrates (Ag@PVP, Au@Ag NCs) for similar aminoglycoside antibiotics

[0073] Take Ag@PVP sol and 10 -5 Gentamycin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin were mixed with a fixed volume ratio of 1:1, and the pH value was adjusted to 5-6. The surface enhanced Raman spectra of gentamicin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin were obtained with an excitation wavelength of 785 nm.

[0074] from Fig. 9 It can be seen that when Ag@PVP sol is mixed with different aminoglycoside antibiotics, it can be observed from the Raman spectrum that Ag@PVP sol as a SERS substrate cannot distinguish the same type of aminoglycoside antibiotics.

[0075] Take Ag@PVP sol and 10 -5 M Gentamycin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin were mixed, and then Au@Ag NCs sol was added to fix the volume ratio of Au@Ag NCs to Ag@PVP and antibiotic mixed solution to 1:1, and the pH value was adjusted to 5-6. The surface enhanced Raman spectra of gentamicin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin were obtained with an excitation wavelength of 785 nm.

[0076] Fig.10A in the middle is the SERS spectra of different aminoglycoside antibiotics gentamicin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin solutions; Fig.10 B is the Raman characteristic peak of gentamicin and other aminoglycoside antibiotics at 786 cm -1 The other aminoglycoside antibiotics were tested under the same conditions. Fig.10 It can be seen that under acidic conditions, when Au@Ag NCs were added to the mixed solution of Ag@PVP sol and sample solution, only gentamicin was -1 The other aminoglycoside antibiotics do not have such characteristics. Among them, amikacin, streptomycin, tobramycin, neomycin and kanamycin have obvious Raman characteristic peaks at 786 cm -1 A smaller characteristic peak appeared on the left side of the graph, and the characteristic peaks of netilmicin and sisomicin appeared at 1697 cm -1 Therefore, under acidic conditions (pH = 5-6), Ag@PVP and Au@Ag NCs as SERS substrates can distinguish gentamicin, netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin, confirming that the detection system is specific for gentamicin.

[0077] The present invention uses Ag@PVP and Au@Ag NCs as SERS substrates to achieve qualitative and quantitative analysis of gentamicin. The linear detection range of gentamicin is 10 -5 ~10 -9 M, the detection limit was 6.23 × 10 -10 M, the relative standard deviation of SERS intensity is less than 10%. Ag@PVP and Au@Ag NCs as SERS substrates have the advantages of low cost, good stability, and high detection efficiency, and can be widely used in practical detection in SERS detection of antibiotics. In addition, this method is easy to operate, has high accuracy and sensitivity, does not require complex operating techniques, and can meet the requirements of large-scale and rapid analysis and detection.

Claims

1. A multidimensional plasmon coupling system based on Ag@PVP and Au@Ag NCs was used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized by: The following steps are involved: 1) Preparation of Ag@PVP core-shell nanoparticles; 2) Preparation of Au@Ag NCs sol; 3) The gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles, and then Au@Ag NCs sol was added to distinguish gentamicin from other homologues through the Raman characteristic peaks of gentamicin; 4) Quantitative analysis and detection of gentamicin.

2. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: In step 1), a sodium citrate reduction method is used to prepare a silver sol, and then PVP is added to the silver sol to obtain the Ag@PVP core-shell nanoparticles.

3. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: In step 2), a gold seed solution and a growth solution are synthesized separately, the two solutions are mixed and allowed to stand to obtain a gold growth solution, the gold growth solution is then reacted with a CTAC solution, and then a silver nitrate solution and an ascorbic acid-CTAC solution are simultaneously injected to obtain the Au@Ag NCs sol.

4. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: The gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles to induce the aggregation of Ag@PVP. The gentamicin peak was at 948 cm -1 Raman characteristic peaks appear at After the addition of Au@AgNCs sol, Au@Ag NCs regulated the surface plasmon of Ag@PVP, causing the Raman characteristic peak of gentamicin to shift from 948 cm -1 The displacement is 786 cm -1 .

5. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: The distinction between gentamicin and other homologues refers to the Raman characteristic peak position of gentamicin appearing at 786 cm -1 , other homologues did not appear.

6. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 or 5 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: Such other homologs include netilmicin, sisomicin, amikacin, streptomycin, tobramycin, neomycin and kanamycin.

7. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: As the concentration of the gentamicin sample solution increases, the intensity of the SERS characteristic peak of gentamicin will increase. A standard curve is established using the relationship between the intensity of the SERS characteristic peak of gentamicin and the concentration to perform quantitative analysis and detection on the gentamicin solution.

8. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: The linear detection range of gentamicin is 10 -5 ~10 -9 M, the detection limit was 6.23 × 10 -10 M, the relative standard deviation of SERS intensity is less than 10%.

9. The multidimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: The pH of SERS detection was 5-6 after the gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles and Au@Ag NCs sol.

10. The multi-dimensional plasma coupling system based on Ag@PVP and Au@Ag NCs as claimed in claim 1 is used for surface enhanced Raman spectroscopy (SERS) detection of gentamicin, characterized in that: SERS detection was performed within 10 s after the gentamicin sample solution was mixed with Ag@PVP core-shell nanoparticles and Au@Ag NCs sol.

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