Sensor for detecting copper ions and magnesium ions and preparation method thereof

Abstract

The invention discloses a sensor for detecting copper ions and magnesium ions and a preparation method thereof. The sensor is used for rapidly detecting copper ions and magnesium ions in lake water, tap water and mineral water. According to the technical method, on the basis of an agglomeration mechanism, amino on a benzene ring in a modifier 5-(3-aminophenyl)-1H-tetrazole can form a specific bonding effect with gold nanoparticles, nitrogen atoms on a tetrazole ring of the modifier can generate a coordination effect with target metal ions, so that the aggregation state of a gold nano solution is changed, and then the color of the solution is changed; the peak position and the absorption intensity of a surface plasmon resonance absorption peak of the gold nanoparticles are changed, and whether a sample contains the copper ions and the magnesium ions or not can be rapidly detected and the content of the copper ions and the magnesium ions can be quantitatively calculated by utilizing naked eyes and an ultraviolet-visible light spectrum for judgment, so that rapid detection of the copper ions and the magnesium ions in the sample is realized. The scheme has the advantages of simplicity in operation, low cost, stability, good repeatability, wide application range and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of nano materials, and in particular relates to a sensor for detecting copper ions and magnesium ions and a preparation method thereof. Background Art

[0002] Water is an essential resource for human survival. However, the widespread use of metal ions in various production activities will produce a large amount of industrial wastewater containing metal ions, which has serious toxic effects on the environment and human health. Therefore, researchers are committed to exploring simpler and more efficient detection of metal ions in water, including copper ions and magnesium ions. Copper is the third most abundant metal on earth (after iron and zinc). In addition, copper is an essential element for most organisms. Copper ions are catalysts for various metal enzymes and proteins in organisms and play a vital role in various biological processes and metabolic pathways. Therefore, in order to ensure normal biochemical processes, the copper content in organisms must be maintained within a reasonable numerical range. Low copper content may cause anemia, but high copper content may cause gastrointestinal diseases and even damage the liver and kidneys. Excessive copper ions in organisms are usually caused by water pollution. Magnesium ions are the second largest cation in human cells after potassium ions. As a cofactor for more than 300 enzymes, they play an important role in controlling ion transport, structural stability of proteins, enzymes and nucleic acids. Although magnesium is not a heavy metal, insufficient magnesium ions in the body may lead to a variety of diseases, including hypocalcemia and hypokalemia, and excessive intake of magnesium ions can also have a great impact on the human nervous system, urinary system and hematopoietic system. In addition, the water hardness caused by magnesium ions will involve cerebrovascular disease and cardiovascular risks, which is a very concerned issue in domestic and industrial wastewater management. Therefore, it is crucial to develop a portable and efficient method for detecting copper ions and magnesium ions in environmental water.

[0003] At present, the traditional methods for detecting metal ions rely on the interconnection of large and complex instruments, such as inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS) and electrochemical (EC) technology. However, these methods require expensive equipment and well-trained operators and cannot meet the needs of on-site real-time detection. In recent years, many researchers are no longer satisfied with traditional and time-consuming detection methods, but choose portable and efficient methods to detect harmful substances, such as colorimetry. Colorimetry refers to a method of determining the concentration of a target substance by measuring the color depth of a solution in the presence of a colorimetric probe. It has the characteristics of rapid detection, easy observation, and high sensitivity. This method can be combined with fluorescence or UV-visible spectroscopy detection to achieve qualitative and quantitative dual detection. It has a wide range of applications in environmental monitoring, food inspection, clinical diagnosis and other fields. In recent years, the rapid development of nanotechnology has prompted scientific researchers to study gold nanomaterials for the detection of target pollutants. Compared with copper nanomaterials and silver nanomaterials, gold nanomaterials have low toxicity, high stability and good biological inertness. Gold nanoparticles (AuNPs) are the best form of gold nanomaterials and show no toxicity to zebrafish, a model that is highly homologous to the human genome. Therefore, when AuNPs are released into the environment, they will not have an adverse effect on the environment. The colorimetric detection method based on AuNPs can achieve reasonable functional modification of the gold nanosurface by specific ligands, thereby changing the dispersion / aggregation state of AuNPs in the solution and producing color changes and changes in the intensity and displacement of the resonance absorption peak, meeting the goal of rapid and accurate on-site detection, and easily identifying the presence of analytes with the naked eye. Based on the programmability of DNA, researchers have attempted to use gold nanoparticles modified with DNAzymes to detect metal ions by color changes. However, this method still requires complex pretreatment and expensive raw materials, which does not meet the basic goal of simple / real-time on-site detection of the present invention. Summary of the invention

[0004] The technology to be solved by the present invention is to provide a functionalized gold nanoparticle with high sensitivity, low detection limit and good selectivity for the above-mentioned technical problems. The gold nanoparticle is used as a colorimetric detection sensor for rapid and convenient detection of copper ions and magnesium ions in lake water, tap water and mineral water.

[0005] The present invention selects 5-(3-aminophenyl)-1H-tetrazole as a modifier to prepare functionalized gold nanoparticles for detecting copper ions and magnesium ions, and has high sensitivity and good specificity. The naked eye detection limit (LOD) of copper ions is 30.0 μM, and the ultraviolet visible spectrum detection limit is 0.191 μM. The naked eye detection limit (LOD) of magnesium ions is 300.0 μM, and the ultraviolet visible spectrum detection limit is 0.337 μM.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for preparing a sensor for detecting copper ions and magnesium ions, wherein sodium citrate is used as a reducing agent and a stabilizer, and 5-(3-aminophenyl)-1H-tetrazole is used as a modifier. First, gold nanoparticles are prepared by a sodium citrate reduction method, trivalent gold in a chloroauric acid solution is reduced to zero-valent gold, and then a functionalized gold nanoparticle aqueous solution is prepared by adding 5-(3-aminophenyl)-1H-tetrazole modifier; a series of copper ion standard solutions of different concentrations are prepared by using a copper ion standard solution and ultrapure water, and then added to the gold nanoparticle aqueous solution, and the color of the solution gradually changes from wine red to gray blue; 5-(3-aminophenyl)-1H-tetrazole is used as a modifier of gold nanoparticles, and the nitrogen atom on the tetrazole ring of the 5-(3-aminophenyl)-1H-tetrazole is coordinated with the target metal ion, causing the aggregation of gold nanocolloid particles, so that the color of the system changes from wine red to gray blue, and the naked eye colorimetric qualitative detection of copper ions in the sample is realized. The change in the aggregation state of gold nanoparticles causes a change in the surface plasmon resonance absorption (SPR) of gold nanoparticles. The quantitative detection of copper ions can be achieved based on the change in the intensity and displacement of the SPR absorption peak. The procedure and principle for detecting magnesium ions are the same as those for copper ions.

[0008] The structure of 5-(3-aminophenyl)-1H-tetrazole is shown in the following formula (1):

[0009]

[0010] The present invention provides a method for preparing a sensor for detecting copper ions and magnesium ions, which specifically comprises the following steps:

[0011] Add tetrahydrate chloroauric acid aqueous solution into a three-necked flask, heat and stir until boiling, quickly add sodium citrate aqueous solution, continue stirring and reacting for 15 to 20 minutes, the color of the solution gradually changes from light yellow to dark purple and finally to wine red, stand and cool to room temperature, and obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0012] When detecting copper ions and magnesium ions, the prepared solution is diluted by half with deionized water, and then 5-(3-aminophenyl)-1H-tetrazole at the best optimized concentration is added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions and magnesium ions. The sensor can be used to detect copper ions and magnesium ions in a sample to be tested;

[0013] The copper ion is divalent Cu 2+ Ion, magnesium ion is divalent Mg 2+ ion;

[0014] The concentration of the tetrahydrate chloroauric acid aqueous solution is 0.25 mM;

[0015] The pH range of the gold nanoparticle aqueous solution is 2 to 9;

[0016] The concentration of the 5-(3-aminophenyl)-1H-tetrazole is 40 μM;

[0017] The concentration of the sodium citrate aqueous solution is 38.8 mM.

[0018] The prepared functionalized gold nanoparticle aqueous solution was mixed with 2+ and Mg 2+ The standard solution reaction was carried out, and the standard colorimetric cards with different copper ion and magnesium ion concentrations were made according to the color change of the solution (such as Figure 4 and Figure 5 The sample to be tested reacts with the gold nanoparticle aqueous solution, and the color of the sample solution is compared with the standard card, which is used for on-site naked eye colorimetric detection of copper ions and magnesium ions in the sample to be tested under different environments.

[0019] The prepared functionalized gold nanoparticles aqueous solution was mixed with 2+ The peak position and intensity changes of the surface plasmon resonance absorption peak of the gold nanoparticles in the solution after the reaction were tested by UV-visible absorption spectroscopy (such as Figure 6 As shown), including the experimental results of the blank sample, the intensity ratio of the SPR resonance absorption peak at the wavelength corresponding to the peak is plotted against the concentration of the copper ion solution to draw a standard curve (as shown Figure 7 The sample to be tested reacts with the gold nanoparticle aqueous solution, and the UV-visible absorption spectrum test results are substituted into the standard curve for comparison and calculation to achieve quantitative detection of copper ions.

[0020] The detection limit of copper ions is 30.0μM by naked eyes and 0.191μM by UV-visible spectrum.

[0021] The prepared functionalized gold nanoparticles aqueous solution was mixed with Mg 2+ The standard solution reaction was carried out, and the peak position and intensity change of the surface plasmon resonance absorption peak of the gold nanoparticles in the solution after the reaction were tested by UV-visible absorption spectroscopy, including the experimental results of the blank sample. The intensity ratio of the SPR resonance absorption peak at the wavelength corresponding to the peak was plotted against the concentration of the magnesium ion solution to draw a standard curve (such as Figure 8 The sample to be tested reacts with the gold nanoparticle aqueous solution, and the UV-visible absorption spectrum test results are substituted into the standard curve for comparison and calculation to achieve quantitative detection of magnesium ions.

[0022] The naked eye detection limit of magnesium ions is 300μM, and the UV-visible spectrum detection limit is 0.337μM.

[0023] The sample to be detected can be lake water, tap water, or mineral water.

[0024] The present invention provides a sensor for detecting copper ions and magnesium ions and a preparation method thereof, and a method for detecting Cu ions and magnesium ions by using the prepared sensor. 2+ and Mg 2+ Ion technology, which is based on the agglomeration mechanism and uses metal Cu 2+ and Mg 2+ The coordination of the ions with the nitrogen atom on the tetrazole ring of the organic ligand 5-(3-aminophenyl)-1H-tetrazole causes the aggregation of gold nanoparticles ( Figure 2 and Figure 3 ), which changes the color of the solution and causes the peak position and absorption intensity of the gold nanoparticle surface plasmon resonance absorption peak to change. Therefore, by directly using the naked eye and UV-visible spectrophotometer to determine whether the sample contains copper ions or magnesium ions and the content of the ions, it is possible to quickly detect whether the sample contains copper ions or magnesium ions and determine the content of the ions, thereby realizing the determination of Cu in the sample. 2+ and Mg 2+ Rapid qualitative and quantitative detection of ions.

[0025] Compared with the prior art, the present invention is characterized in that:

[0026] The present invention synthesizes a functionalized gold nanocolorimetric sensor modified with 5-(3-aminophenyl)-1H-tetrazole and can be used to detect metal copper ions and magnesium ions in water. The method is simple to operate, has readily available raw materials, low cost, fast detection, high sensitivity and specificity, and can be observed by naked eye colorimetry on site. The specific advantages of this work are: ① the naked eye detection limit (LOD) of copper ions is 30.0 μM, the ultraviolet visible spectrum detection limit is 0.191 μM, and the linear relationship is good (R 2 =0.94), the naked eye detection limit (LOD) of magnesium ions was 300.0 μM, and the UV-visible spectrum detection limit was 0.337 μM, with a good linear relationship (R 2 =0.99); ② No further processing of gold nanoparticles is required, and the response time is short; ③ Strong anti-interference ability. This detection technology is suitable for Cu in lake water, tap water, mineral water and other complex systems 2+ and Mg 2+ The rapid detection of ions has a wide range of application values.

[0027] The amino group in the modifier 5-(3-aminophenyl)-1H-tetrazole used in the present invention can form a specific bonding effect on the synthesized gold nanoparticles, so that the gold nanoparticles have a unique stability; in addition, the nitrogen atom on the tetrazole ring in the organic ligand 5-(3-aminophenyl)-1H-tetrazole can coordinate with the target metal ion. In the absence of copper ions or magnesium ions, the gold nanoparticles do not aggregate. After adding the target ions, the nitrogen atom on the tetrazole ring in the 5-(3-aminophenyl)-1H-tetrazole can coordinate with the copper ions or magnesium ions, and the amino group in the 5-(3-aminophenyl)-1H-tetrazole connects the gold nanoparticles, and the 5-(3-aminophenyl)-1H-tetrazole is like a bridge, linking the gold nanoparticles with the target metal ions, causing the gold nanoparticle solution to present an aggregated state, which is visible to the naked eye, and the color changes from wine red to gray blue. The above-mentioned specific performance parameters make the prepared sensor have specific detection performance parameters, so that the detection results have specific sensitivity, selectivity and detection limit. The naked eye detection limit of copper ions is 30.0 μM, the ultraviolet visible spectrum detection limit is 0.191 μM, and the naked eye detection limit of magnesium ions is 300 μM, and the ultraviolet visible spectrum detection limit is 0.337 μM. Therefore, the technical solution formed by the present invention has unique detection technical parameters and has specific application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a TEM image provided by Example 1 of the present invention, and the particle diameter ranges from 10 to 15 nm.

[0029] Figure 2 The functionalized gold nanoparticle aqueous solution prepared by the present invention is added with Cu 2+ TEM image of the aggregate after.

[0030] Figure 3 Add Mg to the functionalized gold nanoparticle aqueous solution prepared by the present invention. 2+ TEM image of the aggregate after.

[0031] Figure 4 The invention provides standard colorimetric cards (10-100 μM) with different copper ion concentrations.

[0032] Figure 5 The invention provides standard colorimetric cards (50-1000 μM) with different magnesium ion concentrations.

[0033] Figure 6 The different concentrations of Cu provided by the present invention 2+ The UV-visible absorption spectra were measured by adding the ion standard solutions into the prepared functionalized gold nanoparticle aqueous solution.

[0034] Figure 7 The invention provides a method for testing Cu2+ Standard curve of ion concentration.

[0035] Figure 8 For testing Mg provided by the present invention 2+ Standard curve of ion concentration.

[0036] Fig. 9 Colorimetric photograph of the selectivity experiment provided by the present invention.

[0037] Fig.10 The selectivity experiment diagram provided by the present invention presents the UV-visible spectra of different ions, with the horizontal axis being the wavelength and the vertical axis being the corresponding absorbance value A 651nm / A 522nm ratio.

[0038] Fig.11 This is a colorimetric photograph of the anti-interference experiment provided by the present invention.

[0039] Fig.12 This is an anti-interference experimental diagram provided by the present invention, showing the ultraviolet spectrum of a mixed ion solution composed of copper ions and various ions. The horizontal axis is the wavelength and the vertical axis is the corresponding absorbance value A 651nm / A 522nm ratio. DETAILED DESCRIPTION

[0040] The present invention is further described below by means of specific examples.

[0041] Add tetrahydrate chloroauric acid aqueous solution into a three-necked flask, heat and stir until boiling, quickly add sodium citrate aqueous solution, continue stirring and reacting for 15 to 20 minutes, the color of the solution gradually changes from light yellow to dark purple and finally to wine red, stand and cool to room temperature, and obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0042] The prepared solution is diluted by half with deionized water, and then 5-(3-aminophenyl)-1H-tetrazole is added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions and magnesium ions. The sensor can be used to detect copper ions and magnesium ions in the sample to be tested.

[0043] Preparation of copper ion and magnesium ion standard cards:

[0044] Step (1): add 1.0 mL of 12.5 mM chloroauric acid tetrahydrate and 49 mL of ultrapure water to a round-bottom flask to obtain a 0.25 mM chloroauric acid aqueous solution, heat to boiling while stirring, quickly add 2.5 mL of a 38.8 mM sodium citrate aqueous solution, react for 15 to 20 minutes, the solution color gradually changes from light yellow to wine red, and cool to room temperature, dilute the prepared solution by half with deionized water to obtain a gold nanoparticle aqueous solution, and store it in a refrigerator at 4°C for later use; when detecting copper ions or magnesium ions, take 0.8 mL of the prepared gold nanoparticle aqueous solution and 0.1 mL 40 μM 5-(3-aminophenyl)-1H-tetrazole (modifier) ​​is first added into the detection tube at a volume ratio of 8:1, and the pH value of the reaction mixture solution is adjusted to 5, thereby obtaining a functionalized gold nanoparticle aqueous solution modified with 5-(3-aminophenyl)-1H-tetrazole, which is the sensor for detecting copper ions and magnesium ions. The sensor can be used to detect copper ions and magnesium ions in a sample to be tested;

[0045] Step (2): Prepare a series of copper ion standard aqueous solutions of different concentrations using deionized water and 1.0 mM copper ion standard solution, the concentrations being 10 μM, 20 μM, 30 μM, 40 μM, 50 μM, 60 μM, 70 μM, 80 μM, 90 μM and 100 μM, respectively. Take 0.1 mL of copper ion standard solutions of different concentrations and add them to 0.9 mL of the functionalized gold nanoparticle aqueous solution prepared in step (1) above, respectively. Let stand for 20 minutes. Copper ions coordinate with the organic ligand 5-(3-aminophenyl)-1H-tetrazole modified on the surface of gold nanoparticles, causing the gold nanoparticles to aggregate ( Figure 2 ), and the color of the reaction solution changes. According to the different colors reflected by different solution concentrations, a standard colorimetric card with gradient copper ion concentration is obtained, including a card with blank test results ( Figure 4 ).

[0046] Step (3): a series of magnesium ion standard aqueous solutions of different concentrations were prepared with deionized water and 1.0 mM magnesium ion standard solution, the concentrations being 50 μM, 100 μM, 110 μM, 120 μM, 130 μM, 200 μM, 300 μM, 400 μM, 500 μM, 600 μM, 700 μM, 800 μM, 900 μM and 1000 μM, respectively. 0.1 mL of magnesium ion standard solution of different concentrations was added to 0.9 mL of the functionalized gold nanoparticle aqueous solution prepared in step (1) above, and the solution was allowed to stand for 20 minutes. The magnesium ions coordinated with the organic ligand 5-(3-aminophenyl)-1H-tetrazole modified on the surface of the gold nanoparticles to cause the gold nanoparticles to aggregate ( Figure 3), and the color of the reaction solution changes. According to the different colors reflected by different solution concentrations, a standard colorimetric card of gradient magnesium ion concentration is obtained, including a card of blank test results ( Figure 5 ).

[0047] Draw the copper ion standard curve:

[0048] The copper ion standard solutions of different concentrations were added to the functionalized gold nanoparticle aqueous solution modified by 5-(3-aminophenyl)-1H-tetrazole. After standing for 20 minutes, the peak position and intensity of the surface plasmon resonance absorption peak of the gold nanoparticles in each reaction solution in the wavelength range of 400-800nm ​​were measured. The spectrum was plotted with the wavelength as the abscissa and the sample absorbance as the ordinate ( Figure 6 ) and record the absorbance ratio of the UV-visible spectrum at the two peaks of 651nm and 522nm. Use the concentration of the standard sample as the horizontal axis and the absorbance ratio as the vertical axis to draw a standard curve ( Figure 7 ), through linear fitting, we get Cu 2+ The linear equation of the standard curve of the ion solution is: in the range of copper ion concentration 10-100 μM, Y=0.01572X-0.04942, R 2 =0.94.

[0049] Different concentrations of copper ions were detected using standard cards and standard curves. The naked eye detection limit was 30.0 μM, and the UV-visible spectrum detection limit was 0.191 μM. The calculation formula for the UV-visible spectrum detection limit was 3×σ / S, where σ is the standard deviation and S is the slope.

[0050] Draw a standard curve for magnesium ion:

[0051] The above magnesium ion standard solutions of different concentrations were added to the functionalized gold nanoparticle aqueous solution modified by 5-(3-aminophenyl)-1H-tetrazole, and after standing for 20 minutes, the peak position and intensity of the surface plasmon resonance absorption peak of the gold nanoparticles in each reaction solution in the wavelength range of 400-800nm ​​were measured, and the UV-visible spectrum absorbance ratio at the two peaks of 670nm and 522nm was recorded. The standard curve ( Figure 8 ), and through linear fitting, we get Mg 2+ The linear equation of the standard curve of the ion solution is: in the range of magnesium ion concentration of 150-300 μM, Y=0.00889X-1.2286, R 2 =0.99.

[0052] Different concentrations of magnesium ions were detected using standard cards and standard curves. The naked eye detection limit was 300 μM, and the UV-visible spectrum detection limit was 0.337 μM. The calculation formula for the UV-visible spectrum detection limit was 3×σ / S, where σ was the standard deviation and S was the slope.

[0053] Selective experiment

[0054] In order to investigate the selectivity of the prepared sensor (functionalized gold nanoparticles aqueous solution) for the detection of copper and magnesium ions, 15 different types of ions (500 μM: Fe 2+ , Mn 2+ 、Cd 2+ , Ba 2+ 、Zn 2+ 、Ni 2+ Mg 2+ 、Co 2+ , Fe 3+ , Pb 2+ , Sr 2+ Sn 2+ 、Na + , Ca 2+ ; 30μM:Cu 2+ ) were added to the prepared functionalized gold nanoparticles (AuNPs) aqueous solution, and the obtained colorimetric display was as shown in Fig. 9 As shown, solutions containing copper ions or magnesium ions can functionalize the color of the gold nanoparticle aqueous solution from wine red to gray-blue, while the other 13 ions cannot change the color of the functionalized gold nanoparticle aqueous solution, and its color remains consistent with the blank sample, which is wine red. Fig.10 It can be seen that copper ions (A 651nm / A 522nm ) or magnesium ion (A 670nm / A 522nm The UV spectrum curve of the sample is obviously different from that of the blank sample and the absorbance ratio of the sample containing only other interfering ions. These results show that the sensor has excellent selectivity for the detection of copper ions and magnesium ions.

[0055] Anti-interference experiment

[0056] According to the actual detection needs, the detection method also investigated the anti-interference performance of the prepared sensor for copper ion detection. 0.05mL of 30μM copper ion solution was mixed with 0.05mL of 500μM solutions of 14 other ions to obtain 14 mixed ion solutions containing copper ions and other interferences. The results showed that the color of the mixed ion solution containing copper ions and other interferences changed, which was very different from the color of the blank solution ( Fig.11 ). Anti-interference test diagram is shown in Fig.12As shown, Fig.12 It shows that after a mixed ion solution containing copper ions and other interfering ions is added to the functionalized AuNPs solution, its UV spectrum is significantly different from the absorbance of the blank sample, indicating that the prepared sensor has no effect on copper ion detection in the presence of other ions and has strong anti-interference performance.

[0057] Cu 2+ Ion Detection Example

[0058] Example 1

[0059] Add 50 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat to boiling, quickly add 2.5 mL of 38.8 mM sodium citrate aqueous solution, react for 20 minutes, the solution color gradually changes from light yellow to wine red, and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0060] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions. The sensor can be used to detect copper ions in the sample to be tested; the morphology of the prepared functionalized gold nanoparticles was observed by TEM, and the results showed that the diameter of the functionalized gold nanoparticles ranged from 10 to 15 nm ( Figure 1 ). Finally, 0.1 mL of the sample containing copper ions to be tested was added to carry out a copper ion content test experiment.

[0061] Example 2

[0062] Add 20 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat to boiling, quickly add 1.0 mL of 38.8 mM sodium citrate aqueous solution, react for 20 minutes, the color of the solution gradually changes from light yellow to wine red, stand and cool to room temperature, and obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0063] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture solution was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM; finally, 0.1 mL of the copper ion-containing sample to be detected was added to perform a copper ion content test experiment.

[0064] Example 3

[0065] 15 mL of 0.244 mM chloroauric acid aqueous solution was added to a round-bottom flask, heated to boiling with stirring, and 0.75 mL of 38.8 mM sodium citrate aqueous solution was quickly added. After reacting for 20 minutes, the color of the solution gradually changed from light yellow to wine red. The solution was allowed to stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which was stored in a refrigerator at 4°C for later use;

[0066] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture solution was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM; finally, 0.1 mL of the copper ion-containing sample to be detected was added to perform a copper ion content test experiment.

[0067] Example 4

[0068] "Lake Water" 2+ Detection of ions

[0069] (a) Take 0.1 mL of the actual lake water sample as blank solution A;

[0070] (b) Take 0.1 mL of the actual lake water sample and add copper ion standard solution to prepare a 60 μM copper ion solution as the test solution B;

[0071] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect copper ions.

[0072] If the solution to be tested changes color, copper ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, copper ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the copper ion concentration in the lake water sample to be tested. The test results show:

[0073] The color of the blank group reaction solution A was wine red;

[0074] The color of the sample reaction solution B turns gray-blue;

[0075] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0076] The Cu content was determined by UV-Vis absorption spectrometer. 2+ Ion A of lake water sample B to be tested 651nm / A 522nm The ratio is 1.10, substituting Cu 2+ The linear equation of the ion solution standard curve is Y = 0.01572X-0.04942, and X = 73.1 can be calculated, that is, Cu 2+ The concentration of the ion is 73.1 μM.

[0077] Example 5

[0078] Cu in "tap water" 2+ Detection of ions

[0079] (a) Take 0.1 mL of tap water sample as blank solution A;

[0080] (b) Take 0.1 mL of the actual tap water sample, add the copper ion standard solution to prepare a 40 μM copper ion solution, and use it as the test solution B;

[0081] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect copper ions.

[0082] If the solution to be tested changes color, copper ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, copper ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the copper ion concentration in the tap water sample to be tested. The test results show:

[0083] The color of the blank group reaction solution A was wine red;

[0084] The color of the sample reaction solution B turns gray-blue;

[0085] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0086] The Cu content was determined by UV-Vis absorption spectrometer. 2+ Ions of tap water sample A to be tested B 651nm / A 522nm The ratio is 0.598, substituting Cu 2+ The linear equation of the ion solution standard curve is Y = 0.01572X-0.04942, and X = 41.2 can be calculated, that is, Cu 2+The concentration of the ion is 41.2 μM.

[0087] Example 6

[0088] Cu in "mineral water" 2+ Detection of ions

[0089] (a) Take 0.1 mL of the actual mineral water sample as blank solution A;

[0090] (b) Take 0.1 mL of an actual mineral water sample and add a copper ion standard solution to prepare a 40 μM copper ion solution as the test solution B;

[0091] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect copper ions.

[0092] If the solution to be tested changes color, copper ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, copper ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the copper ion concentration in the lake water sample to be tested. The test results show:

[0093] The color of the blank group reaction solution A was wine red;

[0094] The color of the sample reaction solution B turns gray-blue;

[0095] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0096] The Cu content was determined by UV-Vis absorption spectrometer. 2+ Ion A of the mineral water sample B to be tested 651nm / A 522nm The ratio is 0.594, substituting Cu 2+ The linear equation of the ion solution standard curve is Y = 0.01572X-0.04942, and X = 40.9 can be calculated, that is, Cu 2+ The concentration of the ion is 40.9 μM.

[0097] Mg 2+ Ion Detection Example

[0098] Example 7

[0099] Add 50 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat to boiling, quickly add 2.5 mL of 38.8 mM sodium citrate aqueous solution, react for 20 minutes, the solution color gradually changes from light yellow to wine red, and cool to room temperature to obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0100] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting magnesium ions. The sensor can be used to detect magnesium ions in the sample to be tested; the morphology of the prepared functionalized gold nanoparticles was observed by TEM. Finally, 0.1 mL of the sample containing magnesium ions to be tested was added to perform a magnesium ion content test experiment.

[0101] Example 8

[0102] Add 20 mL of 0.25 mM chloroauric acid aqueous solution to a round-bottom flask, stir and heat to boiling, quickly add 1.0 mL of 38.8 mM sodium citrate aqueous solution, react for 20 minutes, the color of the solution gradually changes from light yellow to wine red, stand and cool to room temperature, and obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use;

[0103] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture solution was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM; finally, 0.1 mL of the magnesium ion-containing sample to be detected was added to perform a magnesium ion content test experiment.

[0104] Example 9

[0105] 15 mL of 0.244 mM chloroauric acid aqueous solution was added to a round-bottom flask, heated to boiling with stirring, and 0.75 mL of 38.8 mM sodium citrate aqueous solution was quickly added. After reacting for 20 minutes, the color of the solution gradually changed from light yellow to wine red. The solution was allowed to stand and cool to room temperature to obtain a gold nanoparticle aqueous solution, which was stored in a refrigerator at 4°C for later use;

[0106] The prepared solution was diluted by half with deionized water, and then 0.8 mL of the above solution and 0.1 mL of 40.0 μM 5-(3-aminophenyl)-1H-tetrazole were added to the detection tube in a volume ratio of 8:1, and the pH value of the reaction mixture solution was adjusted to 5 to prepare a functionalized gold nanoparticle aqueous solution. The morphology of the prepared functionalized gold nanoparticles was observed by TEM; finally, 0.1 mL of the magnesium ion-containing sample to be detected was added to perform a magnesium ion content test experiment.

[0107] Example 10

[0108] Mg in "lake water" 2+ Detection of ions

[0109] (a) Take 0.1 mL of the actual lake water sample as blank solution A;

[0110] (b) Take 0.1 mL of the actual lake water sample and add magnesium ion standard solution to prepare a 210 μM magnesium ion solution as the test solution B;

[0111] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect magnesium ions.

[0112] If the solution to be tested changes color, magnesium ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, magnesium ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the magnesium ion concentration in the lake water sample to be tested. The test results show:

[0113] The color of the blank group reaction solution A was wine red;

[0114] The color of the sample reaction solution B turns gray-blue;

[0115] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0116] The Mg content was determined by UV-visible absorption spectrometry. 2+ Ion A of lake water sample B to be tested 670nm / A 522nm The ratio is 0.692, substituting into Mg 2+ The linear equation of the ion solution standard curve is Y = 0.00889X-1.2286, and X = 216 can be calculated, that is, Mg 2+ The concentration of the ion is 216 μM.

[0117] Embodiment 11

[0118] Mg in tap water 2+ Detection of ions

[0119] (a) Take 0.1 mL of tap water sample as blank solution A;

[0120] (b) Take 0.1 mL of an actual tap water sample, add a magnesium ion standard solution to prepare a 150 μM magnesium ion solution, and use this as the test solution B;

[0121] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect magnesium ions.

[0122] If the solution to be tested changes color, magnesium ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, magnesium ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the magnesium ion concentration in the tap water sample to be tested. The test results show:

[0123] The color of the blank group reaction solution A was wine red;

[0124] The color of the sample reaction solution B turns gray-blue;

[0125] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0126] The Mg content was determined by UV-visible absorption spectrometry. 2+ Ions of tap water sample A to be tested B 670nm / A 522nm The ratio is 0.114, substituting into Mg 2+ The linear equation of the ion solution standard curve is Y = 0.00889X-1.2286, and X = 151 can be calculated, that is, Mg 2+ The concentration of the ion is 151 μM.

[0127] Example 12

[0128] Mg in mineral water 2+ Detection of ions

[0129] (a) Take 0.1 mL of the actual mineral water sample as blank solution A;

[0130] (b) Take 0.1 mL of an actual mineral water sample and add a magnesium ion standard solution to prepare a 210 μM magnesium ion solution as the test solution B;

[0131] (c) The blank solution A and the test solution B (0.1 mL each) were added to 0.9 mL of the gold nanoparticle aqueous solution prepared in Example 1, and the color change was observed for 20 minutes. The color change was compared with the standard card to detect magnesium ions.

[0132] If the solution to be tested changes color, magnesium ions exist in the water sample to be tested, and the concentration of the sample to be tested is determined based on the standard colorimetric card. Alternatively, the UV-visible absorption spectrum of the solution to be tested is obtained. If the intensity and position of the UV-visible absorption peak change, magnesium ions exist in the solution to be tested. The absorbance ratio at the peak is brought into the standard curve to calculate and determine the magnesium ion concentration in the lake water sample to be tested. The test results show:

[0133] The color of the blank group reaction solution A was wine red;

[0134] The color of the sample reaction solution B turns gray-blue;

[0135] The UV-visible absorption spectrometer was used to measure the UV-visible absorption peak intensity and position of the blank group reaction solution, which did not change;

[0136] The Mg content was determined by UV-visible absorption spectrometry. 2+ Ion A of the mineral water sample B to be tested 670nm / A 522nm The ratio is 0.656, substituting into Mg 2+ The linear equation of the ion solution standard curve is Y = 0.00889X-1.2286, and X = 212 can be calculated, that is, Mg 2+ The concentration of the ion is 212 μM.

[0137] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations and improvements made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a sensor for detecting copper ions and magnesium ions, characterized in that: The preparation method comprises the following steps: Add tetrahydrate chloroauric acid (HAuCl4·4H2O) aqueous solution to a round-bottom flask, heat and stir until boiling, add sodium citrate (C6H5Na3O7) aqueous solution, continue stirring and reacting for 15-20 minutes, the color of the solution gradually changes from light yellow to purple-black and finally to wine red, stand and cool to room temperature, and obtain a gold nanoparticle aqueous solution, which is stored in a refrigerator at 4°C for later use; The prepared gold nanoparticle aqueous solution is diluted by half with deionized water, and then 5-(3-aminophenyl)-1H-tetrazole is added as a modifier to prepare a functionalized gold nanoparticle aqueous solution, which is the sensor for detecting copper ions and magnesium ions. The sensor is used to detect copper ions and magnesium ions in a sample to be tested; The copper ion is Cu 2+ Ion, magnesium ion is Mg 2+ ; The concentration of the tetrahydrate chloroauric acid aqueous solution is 0.25 mM; The pH range of the gold nanoparticle aqueous solution is 2 to 9; The concentration of the 5-(3-aminophenyl)-1H-tetrazole is 40 μM; The concentration of the sodium citrate aqueous solution is 38.8 mM.

2. A sensor prepared by the preparation method according to claim 1, characterized in that: The sensor is stable and non-toxic.

3. Use of the sensor prepared by the preparation method according to claim 1, characterized in that: The sensor is used for rapid detection of copper ions in lake water, tap water and mineral water, with a naked eye detection limit of 30 μM and a UV-visible spectrum detection limit of 0.191 μM; the sensor is used for rapid detection of magnesium ions in lake water, tap water and mineral water, with a naked eye detection limit of 300 μM and a UV-visible spectrum detection limit of 0.337 μM.

Images