A kind of gold nanoparticles with controllable morphology, its synthesis method and application in Hg detection in food 2+ detection

Abstract

The present invention discloses a method for synthesizing gold nanoparticles with controllable morphology, comprising the following steps: synthesizing concave gold nanocubes CGN; adding HAuCl4 solution to CTAB solution, mixing evenly and then adding a certain amount of AA to reduce Au 3+ to Au 0 , then adding a certain amount of solution containing I ‑ to prepare a growth solution; adding the concave gold nanocubes CGN and the growth solution to the CTAB solution in a certain proportion and placing them in a water bath at 20-40 °C for reaction for a certain time to prepare gold nanoparticles, and controlling the morphology of the gold nanoparticles by adjusting the different addition amounts of the growth solution. And evaluating the catalytic activity by using the gold nanoparticles as a catalyst to catalyze the reduction of RhB by NaBH4 to obtain the nanoparticles with the best catalytic performance; adding Hg 2+ in the RhB reduction reaction can form a mercury alloy with the gold nanoparticles, and the mercury alloy accelerates the reduction of RhB. Based on this principle, a colorimetric-fluorescent dual-signal sensing method for detecting Hg 2+ is constructed, and the detection limit LOD is 0.2 / 0.12 μM.

Description

Technical Field

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

[0002] Mercury ion (Hg 2+ ) is one of the most dangerous heavy metal pollutants, which is easily transferred from the environment to the food chain and accumulates in the human body, causing serious damage to the brain, nervous system, endocrine system, kidneys, etc. China has clear limit standards for mercury in food: fruits and vegetables, dairy products ≤ 0.01 mg / kg, grains ≤ 0.02 mg / kg, meat and eggs ≤ 0.05 mg / kg, edible fungi ≤ 0.1 mg / kg, aquatic products ≤ 0.5 mg / kg. Therefore, the method for quantitatively detecting Hg 2+ has important practical significance for environmental protection and human health.

[0003] At present, the methods commonly used for detecting mercury in food include atomic fluorescence spectrometry (AFS), cold atomic absorption spectrometry (CV-AAS), liquid chromatography-atomic fluorescence spectrometry, fluorescence probe method, spectrophotometry, and spectrometry-mass spectrometry coupling method, etc. However, the pretreatment process is slightly cumbersome during the determination, and at the same time, it is easy to cause mercury loss and pollute the environment. In addition, in the AFS method, excessive hydrogen is generated during the determination process, which may cause spectral interference and affect the determination result; the instruments and devices used in the cold atomic absorption spectrometry are relatively special and expensive; the detection cost of the spectrometry-mass spectrometry coupling method is relatively high, and the liquid chromatography-atomic fluorescence spectrometry is applicable to the detection of aquatic products, etc. Therefore, improving the mercury detection technology and analyzing the mercury detection technology in various foods are particularly important for ensuring food safety.

[0004] In view of this, it is of great significance to develop new methods to achieve the recognition 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 gold nanoparticle with controllable morphology 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 gold nanoparticle with controllable morphology includes the following steps:

[0008] Step S1, synthesizing concave gold nanocubes CGN;

[0009] Step S2: Add the HAuCl4 solution to the CTAB solution. After mixing, add a certain amount of AA to reduce Au 3+ to Au 0 , and the color of the solution changes from golden yellow to colorless. Then add a certain amount of the solution containing I - to prepare the growth solution;

[0010] Step S3: Add CGN and the growth solution to the CTAB solution in a certain proportion, and place it in a water bath at 20 - 40 °C for a certain reaction time. Then, prepare gold nanoparticles through centrifugal purification; the volume ratio of CGN to the growth solution is 2:0.125 - 5, and the morphology of the gold nanoparticles is controlled by adjusting the different addition amounts of the growth solution.

[0011] Furthermore, in Step S1, the steps for synthesizing concave gold nanocubes CGN are as follows:

[0012] Add 206 μL of HAuCl4 solution with a concentration of 24.28 mM to 10 mL of CTAB aqueous solution with a concentration of 0.1 M, and then inject 75 μL of NaOH with a concentration of 1 M. The color of the solution changes to light yellow;

[0013] Add 10 μL of H2O2 with a mass concentration of 30% under stirring conditions;

[0014] Add 300 μL of AA with a concentration of 0.1 M under stirring conditions, and then place the reactants in a water bath at 25 - 35 °C for 10 - 20 min to obtain concave gold nanocubes CGN.

[0015] Furthermore, in Step S2, the specific steps for preparing the growth solution are as follows:

[0016] Add 206 μL of HAuCl4 with a concentration of 24.28 mM to 10 mL of CTAB solution with a concentration of 0.1 M, shake well, add 300 μL of AA with a concentration of 0.1 M, and the color of the solution changes from golden yellow to colorless. Then add 25 μL of KI with a concentration of 0.1 M and stir to prepare the growth solution.

[0017] The present invention also provides a gold nanoparticle with controllable morphology, which is prepared by the above method.

[0018] The present invention also provides an application of the gold nanoparticle in the detection of Hg 2+ in food.

[0019] A detection method for Hg 2+ concentration, characterized by comprising the following steps:

[0020] Step S1: After mixing the NaBH4 solution and the RhB solution in proportion, add the above-mentioned shape-controllable gold nanoparticles, and then add the solution to be measured to the reaction solution, and react for a certain period of time at room temperature;

[0021] Step S2: Measure the absorbance difference of the reaction system by colorimetry or measure the fluorescence intensity difference of the reaction system by fluorimetry, and calculate the Hg concentration in the solution to be measured. 2+ Concentration.

[0022] Furthermore, in the gold nanoparticles, the volume ratio of CGN to the growth solution is 1:0.125.

[0023] Preferably, the pH value of the reaction system is 7.

[0024] Preferably, the reaction temperature is 25°C.

[0025] Preferably, the reaction time is 30 min.

[0026] Compared with the prior art, the shape-controllable gold nanoparticles, their synthesis method and application provided by the present invention have the beneficial effects that:

[0027] By adding different amounts of Au / AA / I solution to the concave gold nanocube CGN to regulate its morphology, gold nanoparticles with different morphologies are prepared during the regulation process. And the catalytic activity is evaluated by using the gold nanoparticles as a catalyst to catalyze the reduction of RhB by NaBH4 to obtain the nanoparticles with the best catalytic performance; after adding Hg in the RhB reduction reaction, a mercury alloy can be formed with the gold nanoparticles, and the mercury alloy accelerates the reduction of RhB. Based on this principle, a colorimetric-fluorescent dual-signal sensing method for detecting Hg is constructed, and the detection limit LOD is 0.2 / 0.12 μM. 3+ / AA / I - solution to regulate its morphology, and gold nanoparticles with different morphologies are prepared during the regulation process. And the catalytic activity is evaluated by using the gold nanoparticles as a catalyst to catalyze the reduction of RhB by NaBH4 to obtain the nanoparticles with the best catalytic performance; after adding Hg in the RhB reduction reaction, a mercury alloy can be formed with the gold nanoparticles, and the mercury alloy accelerates the reduction of RhB. Based on this principle, a colorimetric-fluorescent dual-signal sensing method for detecting Hg is constructed, and the detection limit LOD is 0.2 / 0.12 μM. 2+ After adding Hg in the RhB reduction reaction, a mercury alloy can be formed with the gold nanoparticles, and the mercury alloy accelerates the reduction of RhB. Based on this principle, a colorimetric-fluorescent dual-signal sensing method for detecting Hg is constructed, and the detection limit LOD is 0.2 / 0.12 μM. 2+ The detection limit LOD is 0.2 / 0.12 μM. Description of the Drawings

[0028] 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.

[0029] Figure 1 is the ultraviolet-visible spectrum diagram of adding different amounts of growth solution to CGN;

[0030] Figure 2 is the TEM diagram of the Y-X sample in the present invention;

[0031] Figure 3is the schematic diagram of the morphological change of CGN in Au 3+ / AA / I - solution;

[0032] Figure 4 is the effect diagram of Y-X as a catalyst for the reduction of RhB by NaBH4;

[0033] Figure 5 is the change curve diagram of the ultraviolet absorbance, fluorescence change, and reaction time required in the reaction system of Y-0.125 at different pH values;

[0034] Figure 6 is the change curve diagram of the ultraviolet absorbance in the reaction system of Y-0.125 under different temperature conditions;

[0035] Figure 7 A is the ultraviolet-visible spectrum of RhB with the concentration of Hg 2+ changing in the range of 0.5 - 100 μM; Figure 7 B is the linear relationship diagram of ΔA and the concentration of Hg 2+ in the range of 0.5 - 10 μM; Figure 7 C is the fluorescence emission spectrum of RhB with the concentration of Hg 2+ changing in the range of 0.5 - 100 μM; Figure 7 D is the linear relationship diagram of ΔF / F0 and the concentration of Hg 2+ in the range of 0.5 - 10 μM;

[0036] Figure 8 is the selectivity effect diagram of Y-0.125 for different ions. Detailed implementation manners

[0037] 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 objects, features, and advantages of the present invention more obvious and understandable, the following further describes the detailed implementation manners of the present invention with reference to the accompanying drawings.

[0038] In the ranges disclosed herein, the endpoints and any values are not limited to the exact 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, they 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.

[0039] The experimental reagents, experimental equipment, and instruments used in the present invention are as follows:

[0040] 1. Experimental reagents

[0041] Table 1: Experimental reagents

[0042]

[0043] 2. Experimental Equipment and Instruments

[0044] Table 2 Experimental Equipment and Instruments

[0045]

[0046] Synthesis Method of Gold Nanoparticles in Example 1

[0047] A synthesis method of gold nanoparticles includes the following steps:

[0048] Step S1, synthesize concave gold nanocubes CGN;

[0049] The specific method is as follows:

[0050] Add 206 μL 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 μL of NaOH with a concentration of 1 M, and the color of the solution turns light yellow;

[0051] Add 10 μL of H2O2 with a mass concentration of 30% under stirring conditions;

[0052] Add 300 μL of AA with a concentration of 0.1 M under stirring conditions, and then place the reactants in a water bath at 25 - 35 °C for reaction for 10 - 20 min to obtain concave gold nanocubes CGN.

[0053] Step S2, add HAuCl4 solution to CTAB solution, mix well and then add a certain amount of AA to reduce Au 3+ to Au 0 , the color of the solution changes from golden yellow to colorless, and then add a certain amount of solution containing I - to prepare a growth solution;

[0054] The specific method is as follows:

[0055] Add 206 μL of HAuCl4 with a concentration of 24.28 mM to 10 mL of CTAB solution with a concentration of 0.1 M, shake well and then add 300 μL of AA with a concentration of 0.1 M, the color of the solution changes from golden yellow to colorless, and then add 25 μL of KI with a concentration of 0.1 M and stir to prepare a growth solution.

[0056] Step S3, add CGN and the growth solution to CTAB solution in a certain proportion, and place it in a water bath at 20 - 40 °C for reaction for a certain time, and then prepare gold nanoparticles through centrifugal purification; where the volume ratio of CGN to the growth solution is 2:0.125 - 5, and the morphology of gold nanoparticles is regulated by adjusting the different addition amounts of the growth solution.

[0057] In order to study the effect of the addition amount of the growth solution on the morphology of the nanoparticle material, in this embodiment, the volume of CGN is taken as 2 ml, and the volumes of the growth solution are 0 ml, 0.125 ml, 0.5 ml, 1 ml, 1.5 ml, 2 ml, 2.5 ml, 3 ml, 4 ml, and 5 ml respectively. CTAB with a concentration of 0.1 M is added to maintain the volume of the reaction solution at 7 ml, and gold nanoparticle materials of multiple samples are prepared by reacting for 15 min. And according to the addition amount of the growth solution, the prepared nanoparticle materials are named Y-X (X is the amount of the added growth solution), and the specific sample names are: Y-0, Y-0.125, Y-0.5, Y-1, Y-1.5, Y-2, Y-2.5, Y-3, Y-4, Y-5.

[0058] The centrifugal purification method is as follows:

[0059] Take 2 mL of each of the prepared Y-0, Y-0.125, Y-0.5, Y-1, Y-1.5, Y-2, Y-2.5, Y-3, Y-4, Y-4.5, and Y-5 sample solutions and place them in centrifuge tubes. Centrifuge them twice at 7500 rpm for 10 min each time. After the first centrifugation, remove the supernatant and add the same volume of ultrapure water. Shake it for 30 s to mix it evenly and then centrifuge again. After removing the supernatant of the sample after the second centrifugation, add 300 μL of ultrapure water respectively. Then shake the suspension evenly and place it under an ultrasonic device for ultrasonic treatment for 5 min to obtain a uniformly dispersed sample.

[0060] The prepared Y-X nanoparticle materials are characterized by TEM and UV-visible spectrophotometry (UV-vis).

[0061] Please refer to Figure 1 , which is the UV-visible spectrogram of adding different amounts of growth solution to CGN; among them Figure 1 A represents the UV-Vis adsorption spectrum of adding different amounts of growth solution to CGN; Figure 1 B represents the UV-Vis adsorption spectrum of the real-time growth of CGN in the growth solution containing 5 mL Au 3+ / AA / I - The UV-Vis adsorption spectrum of the growth solution. From Figure 1It can be seen that in the growth solution with an increasing amount (0 - 5 mL), the UV-Vis spectrum of CGN reveals a gradual blue shift in the local surface plasmon wavelength and an increase in the absorbance of the sample. The original CGN has a longitudinal LSPR at 765 nm, with typically 6 concave surfaces and 8 corners. When the amount of growth solution is 1.5 mL, the maximum absorption wavelength of Y-2 blue shifts to 567 nm. When the amount of growth solution is greater than 1.5 mL, the maximum absorption wavelengths of Y-2, Y-2.5, Y-3, Y-4, and Y-5 basically remain unchanged, but their absorbances gradually increase from 0.5 to 1.48, indicating that Au 3+ is reduced to Au 0 and deposits and grows on CGN.

[0062] Please refer to Figure 2 , which is the TEM image of the Y-X sample in the present invention. As can be seen from Figure 2 , when adding 0.125 mL of Au 3+ / AA / I - solution, induced by I - , Au 0 will start to deposit at the concave sites of CGN. As the addition amount of Au 3+ / AA / I - solution gradually increases (Y-0.5, Y-0.5, Y-1), the average particle size of CGN gradually increases during the gold filling process (taking the distance between two concave sites of CGN as the standard). CGN changes from the original size of 65 nm (Y-0) to 90 nm (Y-2), and at the same time, the concave sites of CGN are gradually filled, and the sharp corners gradually become round; when the Au 3+ / AA / I - solution increases to 2 mL, the concave sites of CGN will be completely filled, but its size basically remains unchanged (90 ± 2.36 nm). Then, with the addition of the growth solution, under the combined action of the induction of I - and gold deposition, the morphology of CGN is filled into a spherical shape. This change is consistent with the ultraviolet-visible absorption spectrum Figure 1 A.

[0063] Combining the UV-vis diagram of Y-X with the corresponding TEM diagram, it can be concluded that the morphological changes of CGN in the Au 3+ / AA / I - solution are as shown in Figure 3 .

[0064] To determine the specific reaction time of the sample and to illustrate whether the original CGN changes its size and morphology to form the final product, the real-time growth curve of CGN under the condition of a sufficient amount of Au 3+ / AA / I - solution was measured, as shown inFigure 1 As shown in B, from Figure 1 B, it can be seen that the reaction was completed in 25 min, and this real-time curve also indicates that the morphology of CGN changed significantly under the induction of I. - Under the induction of Au 3+ / AA / I - solution, CGN underwent the reduction and deposition of gold and gradually filled the concave nano-gold, resulting in the morphological change from concave to cube and finally to sphere.

[0065] Example 2 Study on the catalytic performance of Y-X

[0066] 100 μL (10 mM) of RhB was taken separately into 12 clean test tubes containing 2 mL of ultrapure water. After shaking well, 100 μL of ultrapure water, Y-0, Y-0.125, Y-0.5, Y-1, Y-1.5, Y-2, Y-2.5, Y-3, Y-4, Y-5 were added in sequence (ultrapure water was added to two test tubes, one was the blank control of this group of samples, and the other was the comparative sample without the nanocatalyst). Then 200 μL of freshly prepared NaBH4 (0.1 M) solution was added, and after shaking for 30 s to mix evenly, the mixture was allowed to react at room temperature for 30 min. RhB in the solution became reduced RhB (Reduced Rhodamine B, r-RhB), and the solution changed from pink to light pink or colorless. The catalytic performance of Y-X was judged by measuring the degree of decrease in the absorbance of rRhB at 554 nm.

[0067] Please refer to Figure 4 , which is the effect diagram of Y-X catalyzing the reduction of RhB by NaBH4. Among them, Figure 4 A represents the spectral change diagram of RhB under UV-Vis after adding the Y-X nanocatalyst; Figure 4 B represents the color change diagram of RhB after adding Y-X and NaBH4 under natural light, Figure 4 C represents the fluorescence change diagram of RhB under a 365 nm ultraviolet lamp after adding Y-X and NaBH4. From Figure 4 it can be seen that the abilities of Y-0, Y-0.125, Y-0.5, Y-1, Y-1.5, Y-2, Y-2.5, Y-3, Y-4, Y-5 to catalyze the reduction of RhB by NaBH4 are different, and the catalytic performance of the prepared nanomaterials can be judged by the degree of decrease in the absorbance of RhB in the ultraviolet spectrum and the fluorescence intensity under the ultraviolet lamp. From Figure 4 A, it can be seen that compared with other samples, Y-0.125 has the best catalytic effect on RhB, and the ultraviolet absorbance value decreases the most compared with the blank group. And combined with Figure 4 B, Figure 4As can be seen from C, the catalytic activity of the reaction solution with Y-0.125 is the best under natural light and ultraviolet light.

[0068] Example 3 Hg 2+ Detection

[0069] Based on the gold nanoparticle material of the present invention, it can be used to catalyze the reduction of RhB by NaBH4, and the absorbance value change corresponding to Y-0.125 is the largest, and the fluorescence change intensity is also the largest. Therefore, Y-0.125 is selected to construct a colorimetric-fluorescent dual-signal sensing detection of Hg 2+ .

[0070] The method for detecting Hg by Y-0.125 is as follows: 2+ is as follows:

[0071] In a reaction system of 2 mL of ultrapure water, 100 μL of RhB, 200 μL of NaBH4, and 200 μL of Y-0.5, 50 μL of Hg 2 + solution was added to make its final concentrations 0, 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100 μM, respectively. Then it was immediately placed in a UV-Vis and fluorescence spectrophotometer to record the spectral changes of RhB.

[0072] The detection of Hg by Y-0.125 2+ Condition optimization

[0073] pH condition optimization:

[0074] RhB is a weakly basic dye, and different pH values have a great influence on it. NaBH4 is unstable under acidic conditions, and the time to produce rRhB will increase. And the Y-X gold nanomaterial is prone to aggregation under alkaline conditions, resulting in poor catalytic activity of the gold nanoparticles. Therefore, the effects of different pH values (pH = 5, 6, 7, 8, 9, 10, 11, 12) on the reaction time, fluorescence intensity of the reaction solution, and ultraviolet absorbance were studied, as Figure 5 shown. As can be seen from Figure 5 , when the pH is too low or too high, the reaction time required is longer. When the pH is 7, the fluorescence quenching effect of RhB is the most obvious, and the ultraviolet absorbance also drops the fastest. Therefore, a solution with pH = 7.0 is selected as the optimal reaction pH.

[0075] Temperature condition optimization:

[0076] Seven different temperatures (10, 20, 25, 30, 35, 40, 45 °C) were selected to evaluate the catalytic activity of Y-X. The ultraviolet absorbance of RhB at different temperatures is as Figure 6 shown. As can be seen from Figure 6It can be seen that after 30 minutes of reaction, it can be observed that the reduction rate of RhB is the fastest at 25 °C. After 25 °C, the absorbance of RhB decreases slightly because rRhB is oxidized in the presence of O2 and RhB is reformed. Therefore, 25 °C was selected as the optimal reaction temperature.

[0077] Standard curve plotting:

[0078] Under the conditions of pH = 7 and reaction temperature T = 25 °C, different concentrations (0, 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100 μM) of Hg 2+ solutions were successively added to the reaction system of catalytic reduction of RhB by NaBH4 containing Y-0.125 nanocatalyst. After reacting for 30 min, the spectral changes of RhB were recorded in a UV-Vis and fluorescence spectrophotometer.

[0079] Please refer to Figure 7 . When the concentration of Hg 2+ in the RhB reduction system was gradually increased (0 - 100 μM), since Hg 2+ would form an amalgam with Y-0.125 nanogold particles, resulting in a significant increase in the catalytic activity of the Y-0.125 nanomaterial, the reduction rate of RhB increased. That is, the absorbance value of RhB at 554 nm would decrease with the increase in the concentration of Hg 2+ . With the concentration of Hg 2+ as the abscissa and the difference in UV-Vis absorbance values ΔA (A0 - A x , A0 is the absorbance of the blank sample, and x is the absorbance of the solution after adding different concentrations of Hg 2+ to the solution) as the ordinate, the change curve of Hg 2+ was plotted. Its linear range was 0.5 - 10 μM, and the linear equation was ΔA = 0.234C Hg(II) - 0.0685 (R 2 = 0.991), and the LOD was 0.2 μM. Correspondingly, under ultraviolet light, as the concentration of Hg 2+ increased, the fluorescence of the reaction solution was gradually inhibited. When it reached 40 μM, its fluorescence was basically inhibited. In the range of 0.5 - 10 μM, ΔF / F0 was linearly correlated with the concentration of Hg 2+ , and the linear equation was: ΔF / F0 = 0.555C Hg(II) + 0.0685 (R 2 = 0.991), and the LOD was 0.12 μM.

[0080] To verify the detection ability of the fluorescence-colorimetric dual-signal detection system in the actual detection of Hg 2+ in the present invention, this method was compared with other fluorescence detection and ultraviolet colorimetric detection methods in the prior art. The comparison results are shown in Table 3:

[0081] Table 3: Comparison of Detection Results of Different Fluorescence / Colorimetric Analysis Methods for Hg 2+ Detection Results

[0082]

[0083] As can be seen from the results in Table 3, the colorimetric-fluorescence dual-signal sensor constructed based on the Y-0.125 nanogold particle material of the present invention for catalyzing the reduction of RhB by NaBH4 system is used to detect Hg 2+ , and has certain advantages in terms of detection limit, sensitivity, and operation method, etc.

[0084] Note: Literature [1]:

[0085] DU J, YIN S, JIANG L, et al. A colorimetric logic gate based on free gold nanoparticles and the coordination strategy between melamine and mercury ions[J]. Chemical communications, 201

[0086] 3, 49(39): 4196-4198.

[0087] Literature [2]:

[0088] DEMIREZEN Y1LMAZ D, AKSU DEMIREZEN D, H. Colorimetric detection of mercury ion using chlorophyll functionalized green silver nanoparticles in aqueous medium[J]. Surfaces and Interfaces, 2021, 22: 100840.

[0089] Literature [3]:

[0090] 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.

[0091] Reference [4]:

[0092] JIANG W,WEI S,ZHANG R.A novel ratiometric fluorescence probe for the detection of cop per(II) and silver(I) based on assembling dye-doped silica core-shell nanoparticles with gold nanoc lusters[J].Microchimica Acta,2023,190(3):105.

[0093] Reference [5]:

[0094] LUO F,ZHU M,LIU Y,et al.Ratiometric and visual determination of copper ions with fluores cent nanohybrids of semiconducting polymer nanoparticles and carbon dots[J].Spectrochimica acta Part A,Molecular and biomolecular spectroscopy,2023,295:122574.

[0095] Example 4 Hg 2+ Detection selectivity experiment

[0096] To detect the detection specificity of this colorimetric and fluorescence dual-signal detection system for Hg in actual water samples 2+ Some common ions in water (Ca 2+ , Mn 2+ , Pb 2+ , Cu 2+ , Mg 2+ , Na + , Cr3+ , Zn 2+ , Cd 2+ , Co 2+ ) was added to this system as interfering ions to verify its specific selectivity for Hg 2+ . The prepared Y-0.125 nanocatalyst, NaBH4, and RhB were reacted with 300 nM of Hg 2+ and 1 μM of interfering ions for 15 min under the optimal reaction conditions, and then the changes in absorbance and fluorescence intensity were measured using an ultraviolet and fluorescence spectrophotometer.

[0097] Please refer to Figure 8 , which is the selectivity effect diagram of Y-0.125 for different ions. Among them, Figure 8 A represents ultraviolet sensing, Figure 8 B represents fluorescence sensing. It can be seen from Figure 8 that only in the presence of Hg 2+ , the absorbance and fluorescence intensity of the RhB solution were significantly enhanced and inhibited, while the changes in absorbance and fluorescence intensity of the solution before and after the reaction with other interfering ions were relatively small. Compared with other ions, it was extremely obvious (P < 0.001). Therefore, this detection system has a high selectivity for Hg 2+ .

[0098] Example 5 Detection of actual samples

[0099] To verify the feasibility of the detection method of the present invention in the detection of actual samples, the yellow croaker purchased from XX Supermarket was detected and analyzed. The treatment of fish samples refers to GB 5009.17-2021 "National Food Safety Standard Determination of Total Mercury and Organic Mercury in Foods". The test results showed that the sample did not contain Hg 2+ . The detection system of the present invention was used to perform spike recovery determination on the sample, and the spike concentrations were 0 μM, 2.5 μM, and 5.0 μM respectively. The detection results are shown in Table 4:

[0100] Table 4: Detection results of Hg 2+ in yellow croaker

[0101]

[0102] It can be seen from Table 4 that the recovery rates of the samples were 98.8% and 99.6% respectively, and the relative standard deviation (RSD) did not exceed 1.5. This indicates that the detection method of the present invention is feasible.

[0103] The nanoparticle material provided by the present invention is used to detect the Hg 2+ content in foods, and has the advantages of low detection limit, high sensitivity, and convenient operation.

[0104] The embodiments of the present invention have been described in detail above 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 gold nanoparticles with controllable morphology, characterized in that, It includes the following steps: Step S1, synthesizing concave gold nanocubes CGN, the steps are as follows: Add 206 μL 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 μL of NaOH with a concentration of 1 M, and the solution color turns light yellow; Add 10 μL of H2O2 with a mass concentration of 30% under stirring conditions; Add 300 μL of AA with a concentration of 0.1 M under stirring conditions, and then place the reactants in a water bath at 25 - 35 °C for reaction for 10 - 20 min to obtain concave gold nanocubes CGN; Step S2, add the HAuCl4 solution to the CTAB solution. After mixing, add a certain amount of AA to reduce Au 3+ to Au 0 . The color of the solution changes from golden yellow to colorless. Then add a certain amount of the solution containing I - to prepare the growth solution. The specific steps are as follows: Add 206 μL of HAuCl4 with a concentration of 24.28 mM to 10 mL of CTAB solution with a concentration of 0.1 M, shake well and then add 300 μL of AA with a concentration of 0.1 M, the solution color changes from golden yellow to colorless, and then add 25 μL of KI with a concentration of 0.1 M and stir to prepare a growth solution; Step S3, add CGN and the growth solution to the CTAB solution in a certain proportion, and place it in a water bath at 20 - 40 °C for reaction for a certain time, and then prepare gold nanoparticles through centrifugal purification; where the volume ratio of CGN to the growth solution is 2:(0.125 - 5), and the morphology of the gold nanoparticles is regulated by adjusting the different addition amounts of the growth solution.

2. A gold nanoparticle with controllable morphology, characterized in that, Prepared by the method described in claim 1.

3. Use of the shape-controllable 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 RhB solution in a certain proportion, add the gold nanoparticles described in claim 2, and then add the test solution to the reaction solution and react for a certain time at room temperature; Step S2, measure the absorbance difference of the reaction system by colorimetry or measure the fluorescence intensity difference of the reaction system by fluorometry, and calculate the Hg 2+ concentration in the test solution.

5. The detection method according to claim 4, wherein The pH value of the reaction system is 7.

6. The detection method according to claim 4, wherein The reaction temperature is 25 °C.

7. The detection method according to claim 4, wherein The reaction time is 30 min.

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