Au-ag nanoparticle alloy material, synthesis method and detection application thereof

Abstract

The application discloses a synthesis method of Au-Ag nanoparticle alloy material, which comprises the following steps: synthesizing gold nanoparticle seeds; adding silver nitrate solution into CTAB solution, and adding a certain amount of H2O2 under alkaline conditions, so that Ag + is reduced to Ag 0 in the solution, the color of the solution gradually changes into transparent color, and a growth solution is prepared; the gold nanoparticle seeds and the growth solution are added into the CTAB solution in proportion, and are placed in a water bath at 20-40 DEG C for reaction for a certain time, Ag 0 after reduction continues to grow in the solution with the gold nanoparticle as a crystal seed, and then Au-Ag nanoparticle alloy material is prepared through centrifugal purification; the morphology of the Au-Ag nanoparticle alloy material is controlled by adjusting the different adding amount of the growth solution. 2+ It is found that after Cu is added in the OPD oxidation reaction, the catalytic activity of the Au-Ag nanoparticle alloy is inhibited, that is, the fluorescence intensity of the OPD reaction solution is reduced, and based on the principle, a ratio fluorescence sensing system is constructed for detecting Cu 2+ in food, and the lower limit of detection (LOD) is 0.08 mu M.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to an Au-Ag nanoparticle alloy material and its synthesis method, as well as its application in Cu... 2+ Applications in detection. Background Technology

[0002] Copper is one of the essential trace elements required by the human body, playing a vital role in the environment and biological systems, such as cellular respiration, bone formation, and electron transfer. Although Cu... 2+ Copper plays a crucial role in the human body, but excessive intake can lead to serious complications such as vomiting, liver damage, dyslexia, and gastrointestinal disorders. Therefore, the detection of copper ions in the environment is of great significance.

[0003] Currently, methods for detecting copper ions include atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS), and mass spectrometry. Although these techniques have high sensitivity and selectivity, they suffer from drawbacks such as high cost, complex procedures, and long detection times, making them difficult to implement in real-world environments.

[0004] Therefore, it is necessary to provide a simple, convenient, highly sensitive, and low-cost detection method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical defects and provide an Au-Ag nanoparticle alloy material for detecting Cu. 2+ It has the advantages of simple operation, convenience, high sensitivity, and low cost.

[0006] The technical solution of the present invention is as follows:

[0007] A method for synthesizing Au-Ag nanoparticle alloy materials includes the following steps:

[0008] Step S1: Synthesize gold nanoseeds;

[0009] Step S2: Add silver nitrate solution to the CTAB solution, and add a certain amount of H2O2 under alkaline conditions to reduce the Ag content in the solution. + Restored to Ag 0 The solution gradually turns transparent, thus obtaining the growth solution.

[0010] Step S3: Add gold nanoseeds and growth solution to CTAB solution in a certain proportion, and place in a water bath at 20-40℃ for a certain period of time to react. The reduced Ag 0Gold nanoparticles were used as seed crystals in solution for further growth, and then Au-Ag nanoparticle alloy materials were prepared by centrifugation and purification. The volume ratio of gold nanoparticle seeds to growth solution was 2:0.125-2.8. The morphology of Au-Ag nanoparticle alloy materials was controlled by adjusting the amount of growth solution added.

[0011] Specifically, in step S3, the water bath temperature can be 20℃, 25℃, 30℃ or 40℃, or other temperature values ​​within this range; the reaction time is 10-30 min, such as 10 min, 15 min, 20 min or 30 min.

[0012] Furthermore, in step S1, the steps for synthesizing gold nanoseeds are as follows:

[0013] 206 μL of 24.28 mM HAuCl4 solution was added to 10 mL of 0.1 M CTAB aqueous solution, and then 75 μL of 1 M NaOH solution was added. The solution color turned light yellow.

[0014] Add 10 μL of 30% H2O2 under stirring conditions;

[0015] Add 300 μL of 0.1 M AA under stirring conditions, and then place the reactants in a water bath at 25-35℃ for 10-20 min to obtain gold nanoseeds.

[0016] Furthermore, in step S2, the steps for preparing the growth solution are as follows:

[0017] 206 μL of 24.28 mM AgNO3 was added to 10 mL of 0.1 M CTAB solution; after mixing well, 75 μL of 1 M NaOH was added, and the solution changed from golden yellow to pale yellow.

[0018] Add 10 μL of 30% H2O2 and stir to allow it to react fully. The solution gradually turns transparent, thus preparing the growth solution.

[0019] The present invention also provides an Au-Ag nanoparticle alloy material, which is prepared by the method described above.

[0020] The present invention also provides an application of the Au-Ag nanoparticle alloy material in OPD catalytic oxidation.

[0021] A catalytic oxidation method for OPD, using the Au-Ag nanoparticle alloy material as a catalyst, allows OPD to react with H2O2 to generate DAP; in the Au-Ag nanoparticle alloy material, the volume ratio of gold nanoseeds to growth solution is 2:0.5-1.5.

[0022] This invention also provides a Cu-based food processing method using the Au-Ag nanoparticle alloy material. 2+ Applications of detection.

[0023] A Cu 2+ The detection method includes the following steps:

[0024] Step S1: After mixing H2O2 and OPD solution in PBS buffer in a certain proportion, add the Au-Ag nanoparticle alloy material, then add the test solution to the reaction solution, and react at a temperature of 10-70℃ for 10-60 min; in the Au-Ag nanoparticle alloy material, the volume ratio of gold nanoseeds to growth solution is 2:0.5-1.5;

[0025] Step S2: Measure the change in fluorescence intensity of the reaction system using a fluorescence spectrophotometer, and calculate the Cu content in the test solution. 2+ concentration.

[0026] Furthermore, in the Au-Ag nanoparticle alloy material, the volume ratio of gold nanoseeds to growth solution is 2:0.5.

[0027] Furthermore, the pH value in the reaction system was adjusted to 8.5, the reaction temperature was 30℃, and the reaction time was 15 min.

[0028] Compared with existing technologies, the Au-Ag nanoparticle alloy material, its preparation method, and its applications provided by this invention have the following advantages:

[0029] The Au-Ag nanoparticle alloy material of the present invention utilizes gold nanoseeds in Ag + The morphology and catalytic activity of the nanomaterial were controlled by regrowth in H2O2 solution; the catalytic activity of Au-Ag nanoparticle alloy material was evaluated by using it as a catalyst for the oxidation of OPD by H2O2, and nanomaterials with good catalytic activity were obtained. Cu was added to the OPD oxidation reaction. 2+ This will subsequently inhibit the catalytic activity of the Au-Ag nanoparticle alloy, i.e., reduce the fluorescence intensity of the OPD reaction solution. Based on this principle, the catalytic activity of Cu in food will be inhibited. 2+ Quantitative analysis was performed. The Au-Ag nanoparticle alloy material of this invention is used for Cu... 2+ The detection limit (LOD) was 0.08 μM. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The images show the UV-Vis spectra of CGN with different Ag growth solutions added.

[0032] Figure 2 This is a TEM image of the NX sample in this invention;

[0033] Figure 3 This is the mapping diagram of the NX sample in this invention;

[0034] Figure 4 This is a schematic diagram of the morphological changes of CGN in the silver growth solution in this invention;

[0035] Figure 5 This is a fluorescence image of an NX-catalyzed OPD solution under ultraviolet light;

[0036] Figure 6 This is a fluorescence curve showing the catalytic conversion of OPD to DAP by N-0.5 at different pH values;

[0037] Figure 7 This is a graph showing the change in fluorescence of OPD catalyzed by N-0.5 at different temperatures;

[0038] Figure 8 The time-dependent detection of Cu in the N-0.5 catalyzed OPD oxidation system 2+ Impact curve;

[0039] Figure 9 (a) is the liquid following Cu 2+ Fluorescence emission spectra as concentration decreases from 0 to 1000 μM; Figure 9 (b) is the relationship between ΔF / F0 and Cu in the range of 0.2-40 μM. 2+ Linear relationship graph of concentration;

[0040] Figure 10 The N-0.5 catalyzed OPD oxidation system for Cu 2+ A diagram illustrating the specificity of the detection. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] The experimental reagents, equipment, and instruments used in this invention are as follows:

[0044] 1. Experimental reagents

[0045] Table 1: Experimental Reagents

[0046]

[0047]

[0048] 2. Experimental equipment and instruments

[0049] Table 2: Experimental Equipment and Instruments

[0050]

[0051] Example 1: Synthesis Method of Au-Ag Nanoparticle Alloy Material

[0052] A method for synthesizing Au-Ag nanoparticle alloy materials includes the following steps:

[0053] Step S1: Synthesize gold nanoseeds;

[0054] Specifically, 206 μL of 24.28 mM HAuCl4 solution was added to 10 mL of 0.1 M CTAB aqueous solution, and then 75 μL of 1 M NaOH was injected. The solution color turned light yellow.

[0055] Add 10 μL of 30% H2O2 under stirring conditions;

[0056] 300 μL of 0.1 M AA was added under stirring, and the reactants were then placed in a 30 °C water bath for 15 min to obtain gold nanoseeds.

[0057] Step S2: Add silver nitrate solution to the CTAB solution, and add a certain amount of H2O2 under alkaline conditions to reduce the Ag content in the solution. + Restored to Ag 0 The solution gradually turns transparent, thus obtaining the growth solution.

[0058] Specifically, 206 μL of 24.28 mM AgNO3 was added to 10 mL of 0.1 M CTAB solution; after mixing thoroughly, 75 μL of 1 M NaOH was added, and the solution changed from golden yellow to pale yellow.

[0059] Add 10 μL of 30% H2O2 and stir to allow it to react fully. The solution gradually turns transparent, thus preparing the growth solution.

[0060] Step S3: Gold nanoseeds and growth solution are added to a 0.1M CTAB solution in a specific ratio and reacted in a 30°C water bath for 15 minutes. The reduced Ag... 0 Au-Ag nanoparticle alloy material was prepared by continuing growth in solution with gold nanoparticles as seed crystals and then purifying by centrifugation.

[0061] To investigate the effect of growth solution volume on the morphology of nanoparticle materials, in this embodiment, gold nanoparticles were prepared with 2 ml of gold nanoseeds and growth solution volumes of 0 ml, 0.125 ml, 0.5 ml, 1 ml, 1.5 ml, 2 ml, 2.4 ml, and 2.8 ml, respectively, while maintaining a reaction solution volume of 4.8 ml. The prepared nanoparticle materials were named NX according to the amount of growth solution added, with specific sample names: N-0, N-0.125, N-0.5, N-1, N-1.5, N-2, N-2.4, and N-2.8.

[0062] The centrifugal purification method is as follows:

[0063] Two mL of each of the prepared Au-Ag nanoparticle alloy solutions was placed in eight centrifuge tubes and centrifuged at 8000 rpm for 10 min. After centrifugation, the supernatant was removed, and an equal volume of ultrapure water was added. The mixture was shaken for 30 s to ensure homogeneity, and then centrifuged again. After the second centrifugation, 400 μL of ultrapure water was added to each sample after removing the supernatant. Finally, the suspension was shaken well and sonicated for 5 min to obtain uniformly dispersed Au-Ag nanoparticle alloy materials.

[0064] The prepared NX nanoparticle materials were characterized by TEM and UV-vis spectrophotometry.

[0065] Please see Figure 1 The images show the UV-Vis spectra of CGN with different Ag growth solutions added. Figure 1The UV spectra of CGN in different growth solutions (0-2.8 mL) revealed a gradual blue shift in the wavelength of localized surface plasmon resonance (LSPR), with absorbance values ​​showing a slow increase followed by a decrease. The original CGN has a longitudinal LSPR at 786 nm, with typical 6 concave facets and 8 corners. When the growth solution volume is 2.8 mL, N-2.8 blue shifts to 504 nm. When the growth solution volume is in the range of 0-1.5 mL, its absorbance (A) increases from 0.958 (N-0) to 1.029 (N-1.5). When the growth solution volume is greater than 1.5 mL, the absorbance values ​​of N-2 (A = 0.924), N-2.4 (A = 0.891), and N-2.8 (A = 0.883) are significantly lower than those of N-1.5, which is considered to be due to an oxidation reaction occurring during this process.

[0066] Please see Figure 2 This is a TEM image of the NX sample in this invention. (The image is derived from...) Figure 2 It can be seen that as the amount of silver growth solution increases, the depressions of the CGN are gradually filled. When a small amount of growth solution is added, Ag is deposited in the depressions of the CGN, but mainly tends to grow at the tips of the CGN (N-0.125, N-0.5, N-1, N-1.5). As the amount of growth solution gradually increases (N-2, N-2.4, N-2.8), the deposition of Ag on the original CGN tips decreases. Conversely, as more Ag growth solution is added, the depressions of the grown nanoparticles continue to be filled until the depressions are completely filled, forming a hexahedral Au-Ag nanoparticle alloy. When the amount of growth solution is further increased, the tips and depressions of the nanoparticles no longer grow. The main reason is that excess H2O2 etches the morphology formed by the deposited nanoparticles, and the nanoparticles begin to show their original morphology again.

[0067] Please refer to the following: Figure 3 and Figure 4 ,in Figure 3 4 is a mapping diagram of the NX sample in this invention, and 5 is a schematic diagram of the morphological changes of CGN in the silver growth solution in this invention, which further confirms the morphological growth trend of the nanoparticle alloy material.

[0068] The particle size was statistically analyzed using ImageJ and Origin software (ImageJ statistics were based on the distance between two opposing indentations of the NX nanoparticles). The average size of the NX samples is shown in Table 3.

[0069] Table 3: Average Size of NX Samples

[0070]

[0071] Note: The number of nanoparticles is greater than 150.

[0072] In summary, CGN regrown in silver growth solution showed that with increasing silver growth solution concentration, the local surface plasmon resonance of CGN red-shifted from 786 nm (N-0) to 504 nm (N-2.8), and then further red-shifted to 798 nm with increasing silver growth solution concentration. UV-Vis, TEM, and their corresponding mapping results indicated that the morphology of CGN underwent a series of morphological transformations in different amounts of silver growth solution. The size of CGN first increased and then decreased, and the UV spectrum gradually blue-shifted with increasing silver growth solution concentration, exhibiting a clear growth and filling process, ultimately forming... Figure 4 The diagram illustrates the changes in morphology.

[0073] Example 2: Study on the catalytic performance of N-X

[0074] 1 mL of PBS (0.2 M), 2.4 mL of OPD (0.1%), and 800 μL of H2O2 (0.3%) were added sequentially to eight clean test tubes. After shaking well, 50 μL of NX solution was added to each tube. After reacting at 40 °C for 15 min, NX catalyzed the conversion of OPD to 2,3-diaminophenazine (DAP). The reaction solution changed from colorless to bright yellow and produced yellow fluorescence.

[0075] The NX catalysts were N-0, N-0.125, N-0.5, N-1, N-1.5, N-2, N-2.4 and N-2.8 prepared in Example 1, and their catalytic activity was evaluated by the fluorescence intensity generated by different NX catalysts in the conversion of OPD to DAP within the same time period.

[0076] Please see Figure 5 This is a fluorescence image of an NX-catalyzed OPD solution under ultraviolet light. Figure 5 It can be seen that, in the presence of H2O2 and OPD, when samples N-0, N-0.125, N-0.5, N-1, N-1.5, N-2, N-2.4, and N-2.8 were added respectively, after reacting for 15 min, NX (N-0.5, N-1, and N-1.5) exhibited strong fluorescence intensity. Furthermore, N-0.5 catalyzed the highest amount of OPD to DAP conversion, indicating the strongest fluorescence intensity. Therefore, N-0.5 showed the best catalytic activity. Testing confirmed that N-0.5 is the nanomaterial with the best catalytic activity among those prepared after CGNs regeneration.

[0077] Example 3 Cu 2+ Detection

[0078] Cu is added to the OPD oxidation reaction 2+This will subsequently inhibit the catalytic activity of the Au-Ag nanoparticle alloy, i.e., reduce the fluorescence intensity of the OPD reaction solution. Based on this principle, the Au-Ag nanoparticle alloy material of this invention is used in Cu... 2+ Detection. Since N-0.5 exhibits the best catalytic activity, it was selected to construct a ratiometric fluorescence sensing system for the detection of Cu in food. 2+ .

[0079] N-0.5 detection of Cu 2+ The method is as follows:

[0080] 800 μL of H₂O₂ (0.3%) was added to 16 test tubes containing 1 mL of PBS (0.2 M) buffer and 2.4 mL of OPD (0.1%) solution. After shaking, 50 μL of N-0.5 nanoparticle solution was added to each tube. Subsequently, 50 μL of Cu₂SO₄ solution was added to each reaction solution to achieve final concentrations of 0, 0.2, 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100, 200, 400, 800, and 1000 μM, respectively. After 30 s, the reaction solution was characterized using a fluorescence spectrophotometer. The emission spectrum of the reaction solution in the wavelength range of 450-750 nm was scanned with 565 nm as the optimal excitation wavelength (slit width 5.0, voltage 700 V).

[0081] N-0.5 detection of Cu 2+ Condition optimization

[0082] To improve the sensitivity of fluorescence sensing, several key experimental parameters (temperature, pH, and time) that primarily affect fluorescence intensity were investigated. Experiments revealed that increasing OPD concentration increases emission intensity, while excessively high concentrations suppress fluorescence intensity. When the OPD concentration was 0.1%, the fluorescence intensity of the oxidized OPD reached a relative equilibrium. Therefore, an optimal OPD concentration of 0.1% was selected for further experiments.

[0083] pH condition optimization:

[0084] Please see Figure 6 The graph shows the fluorescence changes of N-0.5 catalyzing the conversion of OPD to DAP at different pH values. The pH conditions are 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, and 12. Figure 6 It is known that excessively acidic or alkaline reaction environments will affect the sensitivity of fluorescence sensing. Adding 100 μM Cu to N-0.5 at different pH values... 2+ The fluorescence intensity of the system reaches its maximum when pH = 8.5, therefore pH = 8.5 is selected as the optimal value for the detection system.

[0085] Optimization of reaction temperature:

[0086] N⁻⁰.⁵ was used to catalyze the oxidation of OPD by H₂O₂ at 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, and 70℃ to produce fluorescence. 100 μM Cu was added to the detection system at each temperature. 2+ Please see. Figure 7 This is a graph showing the change in fluorescence of OPD catalyzed by N-0.5 at different temperatures. Figure 7 It can be seen that when the excitation wavelength is 390 nm and the fluorescence spectrum at the emission wavelength of 565 nm is detected, the fluorescence intensity of the system gradually increases in the range of 10-30℃, reaching its maximum at 30℃. As the temperature gradually increases, the fluorescence intensity decreases and then tends to stabilize. Therefore, the selected reaction temperature is 30℃.

[0087] Response time optimization:

[0088] Please see Figure 8 The time-dependent detection of Cu in the N-0.5 catalyzed OPD oxidation system 2+ The influence curve. (From) Figure 8 It can be seen that when OPD is catalyzed by N-0.5, the reaction is completed in 15 minutes, and then 100 μM Cu is added. 2+ Subsequently, the activity of the N-0.5 nanocatalyst was inhibited, but as the reaction time was extended, the fluorescence of the reaction solution no longer increased after 60 min and remained stable. Therefore, the reaction time was selected as 15 min.

[0089] Plotting the standard curve:

[0090] Under the conditions of pH=8.5 and reaction temperature of 30℃, 50μL of Cu2SO4 solution was added to the reaction solution to make the final concentrations 0, 0.2, 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100, 200, 400, 800 and 1000μM respectively. After reacting for 15 min, the solution was subjected to spectral scanning under a fluorescence spectrophotometer.

[0091] Please see Figure 9 (a) and Figure 9 (b), where Figure 9 (a) is the liquid following Cu 2+ Fluorescence emission spectra as concentration decreases from 0 to 1000 μM; Figure 9 (b) is the relationship between ΔF / F0 and Cu in the range of 0.2-40 μM. 2+ Linear relationship graph of concentration. From Figure 9 (a) It can be seen that, with Cu 2+ As the amount of N-0.5 nanoparticles increased, the fluorescence emission spectrum of the reaction solution gradually decreased at 565 nm. This is because the activity of N-0.5 nanoparticles in Cu... 2+The oxidation of OPD by H2O2 is inhibited in the presence of ions, and the rate of OPD oxidation by N-0.5 catalyzed by H2O2 decreases, thus the fluorescence intensity of the oxidation product DAP is related to that of Cu. 2+ The concentrations of these components showed a negative correlation.

[0092] Figure 9 In (b), Cu 2+ A standard curve is plotted with concentration on the x-axis and ΔF(F0-F) / F0 on the y-axis, where F0 and F represent the values ​​of concentration in the absence of Cu. 2+ The fluorescence intensity recorded under these conditions indicates that Cu in the range of 0.2–40 μM is within the range of [missing information]. 2+ The concentration showed a linear correlation with the fluorescence intensity of the reaction solution, with the linear equation being: ΔF / F0 = 0.0197C Cu(II) +0.0446(R 2 =0.992). Therefore, this method is effective for Cu. 2+ The LOD is 0.08 μM.

[0093] The sensitivity of the detection method of this invention is compared with that of the prior art for Cu. 2+ The sensitivity of the detection fluorescence analysis method was compared, and the results are shown in Table 4:

[0094] Table 4: Different fluorescence analysis methods for Cu 2+ Comparison of test results

[0095]

[0096] Note: Reference [1]:

[0097] PENG JJ,LING J,TAN Y,et al.Poly(thymine)-templated coppernanoparticles as afluorescence probe for highly selective and rapid detection of cysteine[J].Spectrosco py Letters, 2017,50(3):137-142.

[0098] Reference [2]:

[0099] Jiang W, Wei S, Zhang R. A novel ratiometric fluorescence probe for the detection of copper(II) and silver(I) based on assembling dye-doped silica core–shell nanoparticles with gold nanoclusters[J]. Microchimica Acta, 2023, 190(3): 105.

[0100] Reference [3]:

[0101] Zhang H, Qu Y, Zhao K, et al. A fluorescence “on–off” sensor for the highly selective and sensitive detection of Cu2+ ion[J]. Journal of The Chinese Chemical Society, 2020, 67(6): 1062-1069.

[0102] Reference [4]:

[0103] Luo F, Zhu M, Liu Y, et al. Ratiometric and visual determination of copper ions with fluorescent nanohybrids of semiconducting polymer nanoparticles and carbon dots[J]. Spectrochimica acta Part A, Molecular and biomolecular spectroscopy, 2023, 295: 122574.

[0104] Reference [5]:

[0105] ASADEVI H,PRASANNAKUMARAN NAIR CHANDRIKA KUMARI P,PADMA VATI AMMA R,et al.ZnO@MOF-5 as a Fluorescence “Turn-Off” Sensor for Ultras ensitiveDetection as well as Probing of Copper(II)Ions[J].ACS Omega,2022,7(15):13031-13041.

[0106] This demonstrates that the Cu-based OPD reduction system constructed in this invention, based on N-0.5 nanoparticles, effectively reduces Cu. 2+ Colorimetric sensing detection has certain advantages in terms of detection limit, sensitivity, and operation method.

[0107] Example 4 Cu 2+ Detection Selectivity Experiment

[0108] Add 50 μL of N-0.5 nanoparticles, 800 μL of H2O2, 2.4 mL of OPD, and 1 mL of PBS solution to 11 5 mL centrifuge tubes, respectively. Then add 50 μL of each of the prepared 100 μM ion solutions (Ag) to the corresponding tubes. + Ba 2+ Cd 2+ Cu 2+ Hg 2+ Mg 2 + Na + Pb 2+ Zn 2+ Pb 2+ Zn 3+ CO 2+ Sn 2+ The reaction solution was placed in a 40°C water bath for 15 minutes and then removed. The change in fluorescence intensity was then measured using a fluorescence spectrophotometer.

[0109] Please see Figure 10 It is the N-0.5 catalyzed OPD oxidation system for Cu 2+ A diagram illustrating the specificity of the detection. (From...) Figure 10 It can be seen that when 12 other ions are added, the fluorescence intensity of the reaction solution increases or decreases slightly within 15 minutes. When Cu is added... 2+ When the fluorescence intensity of the reaction solution was significantly suppressed, it was abnormally pronounced compared to other ions (P<0.001). Therefore, this system is not suitable for Cu. 2+ It exhibits strong specificity selection.

[0110] Example 5: Actual Sample Detection

[0111] To evaluate the feasibility of this system in actual sample testing, drinking water from a dormitory building in the South Campus of XX School was used for testing. The results showed that the drinking water did not contain Cu. 2+ It meets the Cu content of GB 5749-2022, my country's "Standards for Drinking Water Quality". 2+ The content of Cu does not exceed the limit standard of 1 mg / L. Using this system for spiked detection, the Cu content in the spiked sample... 2+ The concentrations were 0 μM, 0.5 μM, 1 μM, 5 μM, and 10 μM. The detection results are shown in Table 5.

[0112] Table 5: Cu in drinking water 2+ Test results

[0113]

[0114]

[0115] As shown in Table 5, the recoveries of the sample were 96.0%, 98.0%, 98.2%, and 99.5%, respectively, with relative standard deviations (RSD) ranging from 0.02 to 3.45.

[0116] The Au-Ag nanoparticle alloy material provided by this invention is used for detecting Cu in food. 2+ It has advantages such as low detection limit and convenient operation.

[0117] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for synthesizing Au-Ag nanoparticle alloy materials, characterized in that, It comprises the following steps: Step S1, synthesis of gold nano seeds, the steps are as follows: Add 206 mL of HAuCl4 solution with a concentration of 24.28 mM to 10 mL of CTAB aqueous solution with a concentration of 0.1 M, then inject 75 mL of NaOH with a concentration of 1 M, and the solution color changes to light yellow; Under stirring conditions, add 10 mL of H2O2 with a mass concentration of 30%; Under stirring conditions, add 300 mL of AA with a concentration of 0.1 M, and then place the reactant in a 25-35°C water bath for 10-20 min to obtain gold nano seeds; Step S2, silver nitrate solution is added into CTAB solution, and a certain amount of H2O2 is added under alkaline condition, so that Ag + is reduced to Ag 0 , the color of the solution gradually changes to transparent, and a growth solution is prepared, the steps are as follows: Add 206 mL of AgNO3 solution with a concentration of 24.28 mM to 10 mL of CTAB solution with a concentration of 0.1 M; After mixing evenly, add 75 mL of NaOH with a concentration of 1 M, and the solution color changes from golden yellow to light yellow; Add 10 mL of H2O2 with a mass concentration of 30%, stir to fully react, and the solution color gradually changes to transparent color to prepare a growth solution; Step S3, the gold nano seeds and the growth solution are added into the CTAB solution in proportion, and are placed in a water bath at 20-40℃ for reaction for a certain time, and the reduced Ag 0 The Au-Ag nanoparticle alloy material is prepared by continuing to grow in solution with the gold nanoparticles as seeds, and then purified by centrifugation; wherein the volume ratio of the gold nano seeds to the growth solution is 2:0.5-1.5, and by adjusting the different amounts of the growth solution, the morphology of the Au-Ag nanoparticle alloy material is controlled, so that the Ag mainly grows at the tip of the gold nanoparticles.

2. An Au-Ag nanoparticle alloy material, characterized by, Prepared by the method of claim 1.

3. The Au-Ag nanoparticle alloy material of claim 2 is used in OPD catalytic oxidation.

4. A method for catalytic oxidation of OPD, characterized by, The Au-Ag nanoparticle alloy material of claim 2 is used as a catalyst to make OPD contact with H2O2 to generate oxidation reaction, and DAP is generated; in the Au-Ag nanoparticle alloy material, the volume ratio of gold nano seeds to growth solution is 2:0.5-1.

5.

5. A Cu 2+ concentration detection method characterized by, It comprises the following steps: Step S1, in PBS buffer, mix H2O2 and OPD solution in proportion, then add the Au-Ag nanoparticle alloy material of claim 2, and then add the solution to be measured to the reaction solution, and react at a temperature of 10-70°C for 10-60 min; in the Au-Ag nanoparticle alloy material, the volume ratio of gold nano seeds to growth solution is 2:0.5-1.5; Step S2, the fluorescence intensity change of the reaction system was determined by fluorescence spectrophotometer, and the Cu concentration in the solution to be measured was calculated 2+ concentration.

6. The Cu of claim 5 2+ Method for detecting a concentration, characterized in that In the Au-Ag nanoparticle alloy material, the volume ratio of gold nano seeds to growth solution is 2:0.

5.

7. The Cu of claim 5 2+ Method for detecting a concentration, characterized in that The pH value in the reaction system is adjusted to 8.5, the reaction temperature is 30°C, and the reaction time is 15 min.

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