A concave gold nanoparticle, its synthesis method and detection application

Abstract

The present invention discloses a method for synthesizing concave gold nanoparticles, comprising the following steps: Under alkaline conditions, add HAuCl4 to the CTAB solution. After shaking, the color of the solution changes from golden yellow to light yellow. Then, add H2O2 under stirring conditions to make the solution colorless and transparent, thereby preparing a growth solution; Add an appropriate amount of AA to the growth solution prepared in step S1, and place the reactants in a water bath at 25-40 °C for reaction for 10-20 min to obtain concave gold nanocubes CGN; Take an appropriate amount of CGN and the growth solution prepared in step S1 and add them to the CTAB solution in a certain proportion, and place them in a water bath at 20-40 °C for reaction for a certain period of time, and then obtain regenerated concave gold nanoparticles through centrifugal purification; The volume ratio of CGN to the growth solution is 2:0.125-4, and the morphology of the gold nanoparticles is controlled by adjusting the addition amount of the growth solution. Based on this principle, a method for colorimetric detection of Hg based on inhibiting the catalytic activity of gold nanoparticles is constructed 2+ with a minimum detection limit of 2 nM.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and particularly to a concave gold nanoparticle, a synthesis method thereof, and an application thereof in Hg 2+ detection. Background Art

[0002] Mercury ions (Hg 2+ ) are a kind of highly toxic heavy metal pollutants widely existing. The extensive application in agricultural and industrial production has caused the pollution of mercury compounds in the atmosphere, water and soil. When mercury compounds are consumed by bacteria, plankton, fish and shellfish, and other marine mammals, they will accumulate in the tissues of edible animals and plants through the biological magnification effect of the food chain. When people consume these animals and plants for a long time, a biological enrichment effect will occur, and finally lead to kidney and liver damage, immune system disorders, behavioral disorders, etc. In view of the high toxicity and bioaccumulation of Hg 2+ , the detection of Hg 2+ becomes particularly important.

[0003] Currently, the methods for detecting Hg 2+ mainly include inductively coupled plasma mass spectrometry (ICP-MS), dithizone spectrophotometry, cold atomic absorption method, atomic fluorescence method, etc. Although these methods can detect various metal ions with high sensitivity and high selectivity, they require complex instruments and complex sample preparation processes, thus having problems such as high cost, the need for professional laboratories, and long time consumption, which pose a huge obstacle to the efficient on-site detection of food samples.

[0004] Therefore, it is of great significance to develop a new detection method to realize the identification and quantitative analysis of Hg 2+ . Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical defects and provide a concave gold nanoparticle for detecting Hg 2+ , which has the advantages of simple operation, convenience, high sensitivity, low cost, etc.

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

[0007] A synthesis method of a concave gold nanoparticle, comprising the following steps:

[0008] Step S1, under alkaline conditions, add HAuCl4 to the CTAB solution. After shaking, the color of the solution changes from golden yellow to light yellow, and then add H2O2 under stirring conditions to make the color of the solution become transparent, thereby preparing a growth solution;

[0009] Step S2: Add an appropriate amount of AA to the growth solution prepared in Step S1, and place the reactants in a water bath at 25 - 40 °C for reaction for 10 - 20 min to obtain concave gold nanocubes CGN;

[0010] Step S3: Take an appropriate amount of CGN and the growth solution prepared in Step S1 and add them to the CTAB solution in a certain proportion, and place them in a water bath at 20 - 40 °C for reaction for a certain period of time, and then obtain regenerated concave gold nanoparticles through centrifugal purification; the volume ratio of CGN to the growth solution is 2:0.125 - 4, and the morphology of the gold nanoparticles is regulated by adjusting the addition amount of the growth solution.

[0011] Further, in Step S1, the addition amounts of each component are as follows: 10 mL of a CTAB solution with a concentration of 0.1 M, 206 μL of HAuCl4 with a concentration of 24.28 mM, and 10 μL of H2O2 with a mass concentration of 30%.

[0012] Further, in Step S2, the addition amount of AA is: 300 μL of AA with a concentration of 0.1 M.

[0013] The present invention also provides a kind of concave gold nanoparticles prepared by the above method.

[0014] The present invention also provides the application of the concave gold nanoparticles in the detection of Hg 2+ in food.

[0015] A method for detecting the concentration of Hg 2+ comprises the following steps:

[0016] Step S1: After mixing the NaBH4 solution and the 4-NP solution in a certain proportion, add the above concave gold nanoparticles, and then add the test solution to the reaction solution to form a reaction system;

[0017] Step S2: Measure the absorbance value of the reaction system and the time required for the complete reduction reaction by an ultraviolet-visible spectrophotometer, and measure the concentration of Hg in the solution according to the time required for the complete reduction reaction. 2+ in the solution.

[0018] Further, in the gold nanoparticles, the volume ratio of CGN to the growth solution is 2:2.

[0019] Compared with the prior art, the concave gold nanoparticles, their synthesis method and application provided by the present invention have the beneficial effects that:

[0020] The morphology and catalytic activity of CGN are regulated by regrowth. Under alkaline conditions, by adjusting the growth solution (Au +The amount of / H2O2 solution) was used to regulate the morphology of CGN, and gold nanoparticles with various morphologies such as concave, star-shaped, and multi-branched were synthesized. The catalytic activity of the gold nanoparticles was evaluated by catalyzing the reduction of 4-NP by NaBH4, and it was found that the catalytic activity of the worm-like D-2 nanoparticles was the best. It was experimentally found that the addition of Hg 2+ in this catalytic reduction system would inhibit the catalytic activity of D-2, thereby reducing the reduction rate of 4-NP. Based on this principle, a colorimetric detection method for Hg based on inhibiting the catalytic activity of gold nanoparticles was constructed. 2+ In the range of 0-58 nM, there was a good linear relationship between the concentration of Hg 2+ and the reduction time of 4-NP. The linear equation was: △A = 0.074C Hg(II) + 3.513 (R 2 = 0.995). The lowest detection limit was 2 nM, and it had high selectivity only for Hg 2+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 is the UV-Vis absorption spectrum diagram of adding different amounts of growth solution to CGN;

[0023] Figure 2 is the TEM diagram of the D-X sample in the present invention;

[0024] Figure 3 is the schematic diagram of the regrowth of concave gold nanocubes in the present invention;

[0025] Figure 4 is the bar chart of the average particle size of the D-X sample in the present invention;

[0026] Figure 5 is the effect diagram of the catalytic activity of the D-X sample in the present invention;

[0027] Figure 6 A is the curve of the value of Ln(C t / C0) changing with time, Figure 6 B is the bar chart of the reaction time of each sample when the reactant 4-NP is reduced by more than 99%;

[0028] Figure 7 is the HAADF-STEM image of the D-2 nanomaterial in the present invention;

[0029] Figure 8 is the relationship diagram of Hg in the present invention 2+ versus reaction time;

[0030] Figure 9 is the selectivity effect diagram of D-2 for different ions. Specific embodiments

[0031] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the following further describes the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0032] In the ranges disclosed herein, the endpoints and any values 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, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] The experimental reagents, experimental equipment, and instruments used in the present invention are as follows:

[0034] 1. Experimental reagents

[0035] Table 1: Experimental reagents

[0036]

[0037]

[0038] 2. Experimental equipment and instruments

[0039] Table 2 Experimental equipment and instruments

[0040]

[0041] Example 1 Synthesis method of gold nanoparticles

[0042] Step S1, in a 25 mL glass bottle, sequentially add 10 mL CTAB (0.1 M), 206 μL HAuCl4 (24.28 mM), 75 μL NaOH (1 M). After shaking the solution, the color changes from golden yellow to light yellow. Subsequently, add 10 μL H2O2 (mass concentration 30%) under stirring to make the solution colorless and transparent, and obtain a growth solution;

[0043] Step S2: After stirring for 30 s, 300 μL of AA (0.1 M) was added to the growth solution, and then the reactants were placed in a water bath at 30 °C for 15 min to obtain concave gold nanocubes CGN;

[0044] Step S3: Take 2 mL of each CGN solution and place it in 7 transparent screw-cap glass bottles of 30 mL. Add 0.1 M CTAB and 0 - 4 mL of the growth solution, and keep the volume of the reaction solution for each sample at 6 mL. Then place the glass bottles in a water bath at 30 °C for 15 min, and centrifuge and purify to obtain regenerated concave gold nanoparticles. According to the amount (mL) of the added growth solution, the prepared gold nanoparticle samples are named D-X (X is the amount of the added growth solution), namely named D-0, D-0.125, D-1, D-2, D-3, D-3.4, D-3.8, and D-4.

[0045] The centrifugation and purification method is as follows:

[0046] Take 2 mL of each of the prepared D-0, D-0.125, D-1, D-2, D-3, D-3.4, D-3.8, and D-4 solutions and place them in eight centrifuge tubes. Centrifuge them at 7000 rpm for 10 min. After centrifugation, remove the supernatant and add the same volume of ultrapure water. Shake for 30 s to mix evenly and then centrifuge again. After the second centrifugation, remove the supernatant from the samples and add 400 μL of ultrapure water respectively. Finally, shake the suspension well and place it under an ultrasonic device for ultrasonic treatment for 5 min to obtain uniformly dispersed D-X gold nanoparticles.

[0047] The prepared D-X gold nanoparticles were characterized by ultraviolet spectrophotometer (UV-Vis) and transmission electron microscope (TEM).

[0048] Please refer to Figure 1 , which is the UV-Vis absorption spectrum diagram of adding different amounts of growth solution to CGN, where Figure 1 A represents the UV-Vis absorption spectrum of adding different amounts of growth solution to CGN, Figure 1 B represents the real-time growth UV-Vis absorption spectrum of CGN in 4 mL of growth solution. As can be seen from Figure 1 A, the UV-Vis spectra of adding different amounts of growth solution reveal the phenomenon that the local surface plasmon wavelength first redshifts and then blueshifts, and the absorbance of the samples first rises and then gradually decreases. The original CGN has a longitudinal LSPR at 776 nm, with typical 6 concave surfaces and 8 corners. When the amount of the growth solution is 3 mL, the maximum absorption wavelength of D-3 reaches the maximum value of 845 nm. When the amount of the growth solution is greater than 3 mL, the maximum absorption wavelengths of D-3.4 (806 nm), D-3.8 (769 nm), and D-4 (750 nm) are significantly blueshifted compared with D-3, indicating that an oxidation reaction occurs during this process.

[0049] Please refer to Figure 2 、 Figure 3 and Figure 4 where Figure 2 is the TEM image of the D-X sample in the present invention, Figure 3 is the schematic diagram of the regrowth of concave gold nanocubes in the present invention; Figure 4 is the bar chart of the average particle size of the D-X sample in the present invention. From Figure 2 、 Figure 3 and Figure 4 it can be seen that during the regrowth process of CGN, its particle size increases from 107 nm to 199 nm, and then decreases to 125 nm, which is consistent with the ultraviolet-visible absorption spectrum. The morphology of the D-X sample changes complexly with the addition amount of the growth solution. In the low-dose growth solution (D-0.125), Au 0 tends to deposit at the concave of CGN, forming star-shaped nanoparticles with 6-9 branches. When the addition amount of the growth solution reaches 1 mL, Au 0 grows at the sharp corners and concavities of CGN, forming star-shaped nanoparticles with 10 smaller branches. The D-2 gold nanoparticles have a worm-like morphology with more than 8 tentacles, which may be because the deposition tendency of Au 0 tends to appear on certain surfaces. After growth in 3 mL Au + / H2O2 solution, circular nanoparticles with many rich tips and branches are observed, and the nanoparticle sizes are D-3 > D-2 > D-1 > D-0.125 ( Figure 4 shown). When the amount of the growth solution exceeds 3 mL, the nanoparticles have been oxidized and etched, and the terminal branches become more mature. Especially for D-3.4 and D-3.8, at 4 mL, the nanoparticles become CGN again.

[0050] In the traditional technology, the etching of anisotropic nanoparticles tends to form spherical nanoparticles. For example, gold nanorods and gold nanostars are oxidized into spherical gold nanoparticles. By capturing the real-time ultraviolet-visible spectrum of CGN in 4 mL growth solution to study whether the original CGN changes its size and morphology to form the final product. In the Au + / H2O2 alkaline solution, along with the increase in absorbance, the local surface plasmon resonance will redshift to 845 nm, and then blueshift to 545 nm with the decrease in absorbance ( Figure 1 B). The results show that the formation of the CGN morphology undergoes a series of morphological transformation processes, in which the size and number of branches first increase and then decrease, showing an obvious process of growth first and then etching, and finally forming Figure 2 the observed morphology.

[0051] Example 2 Study on the Catalytic Activity of D-X

[0052] In the presence of NaBH4, D-0, D-0.125, D-1, D-2, D-3, D-3.4, D-3.8 and D-4 were used as catalysts to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP). First, 30 μL of 4-NP solution (10 mM) was added to a glass tube containing 3 mL of ultrapure water. Then, 200 μL of freshly prepared NaBH4 (0.1 M) solution was added. After shaking well, 200 μL of D-X was added as a catalyst, and the color of the solution gradually changed from yellow to colorless. The catalytic activity of D-X was judged by monitoring the change in the peak intensity of the ultraviolet-visible wavelength at 400 nm over time.

[0053] Please refer to Figure 5 , which is the effect diagram of the catalytic activity of the D-X sample in the present invention, where Figure 5 a-5h represents the normalized UV-visible spectrum of 4-NP over time for evaluating the catalytic activity of D-X; Figure 5 a-5h corresponds to D-0, D-0.125, D-1, D-2, D-3, D-3.4, D-3.8, D-4 respectively; Figure 5 a1-5h1 represents the curve of the value of Ln(C t / C0) changing with time (where C0 is the initial concentration of 4-NP, and C t is the concentration of 4-NP at time t (min)), where Figure 5 a1- Figure 5 h1 corresponds to D-0, D-0.125, D-1, D-2, D-3, D-3.4, D-3.8, D-4 respectively. It can be seen from Figure 5 that the prepared gold nanomaterials (D-X) have different catalytic activities for 4-NP. From the reduction time of 4-NP and its reduction rate, among them, the D-2 nanomaterial has the best catalytic activity. It can be seen from Figure 5 c1- Figure 5 h1 that when the D-1, D-2, D-3.4, D-3.8, D-4 samples are added to the reaction system, the reduction of 4-NP does not start immediately, but there is a reaction waiting time. During this period, the conversion rate of 4-NP to 4-AP is basically zero, and the reaction gradually starts after this period ends. It can be understood that this period is the induction time required for the gold nanoparticles to catalyze the reduction of 4-NP. In the present invention, the time when Ln(C t / C0) > -0.1 is defined as the reaction induction time required for the D-X nanomaterial to catalyze the reduction of NaBH4 by 4-NP, and the time period corresponding to Ln(C t / C0) < 0.1 is the actual reaction time for catalyzing the reduction of 4-NP. Finally, the actual reaction time required for the reduction of 4-NP is used to evaluate the catalytic activity of the D-X gold nanoparticles.

[0054] From Figure 6 A and Figure 6 B, it can be seen that when ln(C t / C0) < 0.1, the reduction rate of D-2 is the fastest and the reduction time required for 4-NP is the shortest. The present invention also explores the reason why the D-2 nanomaterial can efficiently catalyze the reduction of 4-NP. Generally, the kinetics of chemical reactions follows the Langmuir-Hinshelwood model, in which 4-nitrophenol ions and hydrogen species are adsorbed on the surface of nanoparticles, and then they meet and react. The conversion of reactants on the surface is the rate-limiting step of the reaction. Under the ultraviolet-visible absorption spectrum, the maximum absorption wavelength of 4-NP is 400 nm, and its decrease over time can determine the reaction rate constant. However, over time, the chemical reaction continues to accelerate ( Figure 5 a1-h1). For other gold nanomaterials, such as spherical gold nanoparticles, gold nanoboxes, and gold nanostars, following the Langmuir-Hinshellwood (L-H) mechanism, the reaction rate remains unchanged or decreases. Obviously, the nanomaterials prepared in the present invention do not follow the L-H kinetics. The reason is that the nanoparticles of the present invention are prepared by rapid deposition of gold, resulting in more crystal defects, dislocations, and atoms exposed at the corners and kinks, which is consistent with Figure 7 the results shown by the HAADF-STEM image of D-2

[0055] Compared with other samples, the reaction time of D-2 is the shortest, only 8 minutes are required. When the growth solution reaches 2 mL, the deposited gold nanoparticles form a worm-like morphology. Compared with CGN (D-0), D-1 and D-2 show higher catalytic ability during the reduction of 4-NP, which can be attributed to their unique branched structure and the exposure of large high-index planes that promote the reaction ( Figure 7 shown).

[0056] Meanwhile, the deposition amount of Au 0 on D-0.125 is very small, so D-0.125 exhibits almost the same catalytic performance as D-0. On the contrary, too much Au 0(D-3) Deposition can hinder and cover the formation of high-index crystal planes and is also not conducive to the reduction of 4-NP. When more growth solutions (D-3.4, D-3.8, and D-4) are added, H2O2 in the growth solution will etch the nanoparticles in the positions with high chemical activity in the reverse direction. Therefore, the catalytic activities of D-3.4, D-3.4, D-3.8, and D-4 are relatively poor. On the other hand, the unique worm-like morphology forms a special multi-stage and multi-branched structure, accelerating the mass transfer rate during the reaction and being conducive to the improvement of the reaction rate. In summary, the high catalytic activity of the D-2 nanomaterial is due to its unique worm-like morphology, more exposed high-index crystal planes, and special hierarchical structure.

[0057] Example 3 Hg 2+ Detection

[0058] Using D-2 as a nanocatalyst to catalyze the reduction of 4-NP (yellow) to 4-AP (colorless) in the presence of NaBH4, when Hg is added to this system 2+ after that, the rate of conversion of 4-NP to 4-AP decreases and the corresponding reaction time also increases accordingly. Based on this, a time-dependent sensing system was established to quantitatively detect Hg 2+ .

[0059] The method for D-2 to detect Hg 2+ is as follows:

[0060] Add 3 mL of ultrapure water, 30 μL of 4-NP, and 200 μL of NaBH4 to a 10 mL test tube. After shaking for 30 s to mix evenly, immediately add 200 μL of the prepared gold nanoparticle (D-2) solution. After shaking well, add 200 μL of Hg 2+ solutions with different concentrations respectively, so that their final concentrations are 0, 5.83, 11.7, 23.3, 35, 46.6, 58.3, 117, 233, 466 nM respectively. Then immediately place it under an ultraviolet fluorescence photometer to scan and record the absorbance value at 400 nm and the time required for complete reduction.

[0061] Please refer to Figure 8 , which is the relationship diagram between Hg 2+ and the reaction time in the present invention, where Figure 8 A represents the time required for the degradation of more than 99% of 4-NP at different Hg 2+ concentrations; Figure 8 B represents the linear relationship between the Hg 2+ concentration and the reaction time in the range of 0 - 58 nM. From Figure 8 A, it can be seen that after adding Hg 2+ to the D-2-catalyzed reduction of 4-NP system, since mercury ions will significantly reduce the catalytic activity of D-2 gold nanoparticles, when gradually increasing Hg to the reaction system2+ concentration, as the concentration of Hg 2+ gradually increases, the degradation rate of 4-NP decreases, and the reaction time of the whole system also prolongs. Therefore, with the concentration of Hg 2+ as the abscissa and the corresponding time required for 4-NP reduction as the ordinate, a linear relationship graph of Hg 2+ concentration and reaction time is obtained. As shown in Figure 8 B, within the range of 0 - 58 nM, there is a good linear correlation between Hg 2+ concentration and reaction time. Its linear equation is: △A = 0.74C Hg(II) + 3.513 (R 2 = 0.995), and the detection limit (LOD) is 2 nM.

[0062] The detection method of the present invention is compared and analyzed with the colorimetric analysis method of the prior art for the detection of Hg 2+ , as shown in Table 3:

[0063] Table 3: Comparison of detection results of different colorimetric analysis methods for Hg 2+ detection

[0064]

[0065] As can be seen from Table 3, the colorimetric sensor constructed by the D-2 gold nanoparticle-catalyzed 4-NP reduction system of the present invention has great advantages in terms of detection lower limit and sensitivity for Hg 2+ detection.

[0066] Note:

[0067] Literature [1]:

[0068] LIQ, WU F, MAO M, et al. A dual-mode colorimetric sensor based on copper nano particles for the detection of mercury-(ii) ions[J]. Analytical Methods, 2019, 11(31): 4014 - 4021.

[0069] Literature [2]:

[0070] Kong Y, Shen J, Fan A. Colorimetric Method for the Detection of Mercury Ions Based on Gold Nanoparticles and Mercaptophenyl Boronic Acid[J]. Analytical sciences, 2017, 33(8): 925 - 930.

[0071] Reference [3]:

[0072] Yang H G, Zha J Q, Zhang P, et al. Nano - spherical CoS as peroxidase for colorimetric detection of H2O2 and Hg2+[C] / / Chinese Chemical Society. Abstracts of the 30th National Symposium on Chemistry of China - Session 3: New Principles and Methods of Nanoscale Sensing, 2016: 90.

[0073] Reference [4]:

[0074] Luo J, Wang Y, Tan K. Colorimetric Detection of Mercury(Ⅱ) Based on Silver Nanoparticles[J]. Acta Chimica Sinica, 2012, 70(18): 1945.

[0075] Reference [5]:

[0076] Sener G, Uzun L, Denizli A. Lysine - promoted colorimetric response of gold nanoparticles: a simple assay for ultrasensitive mercury(II) detection[J]. Analytical chemistry, 2014, 86(1): 514 - 520.

[0077] Example 4 Hg 2+ Detection selectivity experiment

[0078] In 11 clean test tubes, add 3 mL of ultrapure water, 30 μL of 4 - NP, and 200 μL of NaBH4 in sequence. After shaking for 30 s to mix evenly, immediately add 200 μL of the prepared gold nanoparticle (D - 2) solution. After shaking well, add 100 μL of 1 μM of the prepared Cu 2+ , Co 2+ , Sn 2+ , Li 2+ , Pb2+ , Mn 2+ , Zn 2+ , Cd 2+ , Cr 3+ , Cr 6+ and 100 μL of 0.5 μM Hg 2+ ion solution, and then immediately placed in a UV-Vis to record the absorbance value of 4-NP at 400 nm and the time required for complete reduction.

[0079] Please refer to Figure 9 , which is the selectivity effect diagram of D-2 for different ions. As can be seen from Figure 9 , when the Hg 2+ concentration is lower than that of other ion solutions, the effect of Hg 2+ on the degradation rate of 4-NP is significantly different from that of other ions (P < 0.001), indicating that the system has good selectivity for Hg 2+ .

[0080] Example 5 Detection of actual samples

[0081] In a clean 10 mL test tube, add 3 mL of ultrapure water, 30 μL of 4-NP (10 mM), and 200 μL of NaBH4 (0.1 M) in sequence. After shaking for 30 s to mix evenly, immediately add 200 μL of the prepared D-0.2 sample solution. Finally, add 100 μL of the water sample from the drinking fountain in XXX College (untreated before use). After shaking the reaction solution, immediately place it under an ultraviolet fluorescence photometer for real-time scanning and record the absorbance at 400 nm and the time required for complete reduction of 4-NP.

[0082] The results show that the drinking water does not contain Hg 2+ , meeting the limit standard that the content of Hg 2+ in GB 5749-2022 "Hygienic Standards for Drinking Water" does not exceed 0.001 mg / kg. The spiked determination of samples with Cu 2+ (0, 25, 50 nM) was carried out using this system, and the determination results are shown in Table 4:

[0083] Table 4: Detection results of Hg 2+ in drinking water

[0084]

[0085] As can be seen from Table 4, the recovery rates of the drinking water samples are 98.8% and 98.4% respectively, and the relative standard deviation (RSD) does not exceed 2.4.

[0086] The nanoparticle material provided by the present invention is used for detecting Hg 2+Content, with the advantages of low detection limit, high sensitivity, convenient operation, etc.

[0087] The above has made a detailed description of the embodiments of the present invention in conjunction with 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 principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for synthesizing concave gold nanoparticles, characterized in that, It includes the following steps: Step S1: Under alkaline conditions, add HAuCl4 to the CTAB solution. After shaking, the color of the solution changes from golden yellow to light yellow, and then add H2O2 under stirring conditions to make the solution colorless and transparent, thus obtaining the growth solution; Among them, the addition amounts of each component are: 10 mL of CTAB solution with a concentration of 0.1 M, 206 μL of HAuCl4 with a concentration of 24.28 mM, and 10 μL of H2O2 with a mass concentration of 30%; Step S2: Add an appropriate amount of AA to the growth solution prepared in Step S1, and place the reactants in a water bath at 25 - 40 °C for reaction for 10 - 20 min to obtain concave gold nanocubes CGN; among them, the addition amount of AA is: 300 μL of AA with a concentration of 0.1 M; Step S3: Take an appropriate amount of CGN and the growth solution prepared in Step S1 and add them to the CTAB solution in a certain proportion, and place them in a water bath at 20 - 40 °C for reaction for a certain period of time, and then obtain regenerated concave gold nanoparticles through centrifugal purification; among them, the volume ratio of CGN to the growth solution is 2:0.125 - 4, and the morphology of the gold nanoparticles is regulated by adjusting the addition amount of the growth solution.

2. A concave gold nanoparticle, characterized in that, Prepared by the method according to Claim 1.

3. Use of the concave gold nanoparticles according to claim 2 for detecting Hg in food 2+ ​ 4. A method for detecting the concentration of Hg 2+ , characterized in that It includes the following steps: Step S1: Mix the NaBH4 solution and the 4-NP solution in a certain proportion, add the gold nanoparticles according to Claim 2, and then add the test solution to the reaction solution to form a reaction system; Step S2, measure the absorbance value of the reaction system and the time required for the complete reduction reaction by an ultraviolet-visible spectrophotometer, and determine the Hg concentration in the solution according to the time required for the complete reduction reaction. 2+ concentration.

5. The detection method according to claim 4, characterized in that In the gold nanoparticles, the volume ratio of CGN to the growth solution is 2:2.

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