CN101710076B - Lead ion colorimetric detection probes and application method thereof - Google Patents

Abstract

The invention belongs to the technical field of detection, and in particular relates to a lead ion colorimetric detection probe and an application method thereof. The present invention uses glutathione to modify gold nanoparticles as a colorimetric probe. Glutathione uses its sulfhydryl group to combine with gold nanoparticles to coordinate to form a stable structure. The surface contains two free carboxyl structures. During the detection process, the carboxyl group can coordinate with heavy metal ions, and the presence of heavy metal ions Pb ²⁺ in aqueous solution can be indicated by the color change of the solution by using the surface plasmon resonance properties of gold nanoparticles. The invention has high sensitivity and good selectivity, does not need large-scale instruments, can realize in-situ rapid detection, the detection result is intuitive, can be observed with the naked eye, and the operation is simple and low in cost, and the reagents used and the operation process have no toxic and side effects.

Description

A kind of lead ion colorimetric detection probe and application method thereof

technical field

The invention belongs to the technical field of detection, and in particular relates to a lead ion colorimetric detection probe and an application method thereof.

Background technique

Heavy metal ions (mercury Hg ²⁺ ; lead Pb ²⁺ ; cadmium Cd ²⁺ ; copper Cu ²⁺ ), especially mercury, cadmium, lead, copper, etc. have significant biological toxicity. They cannot be degraded by microorganisms in the water body, but can only undergo the process of mutual transformation, dispersion and enrichment of various forms (ie migration). Heavy metal pollution refers to environmental pollution caused by heavy metals or their compounds. It is mainly caused by human factors such as mining, exhaust gas discharge, sewage irrigation and use of heavy metal products. The degree of harm depends on the concentration and chemical form of heavy metals in the environment, food and organisms.

Heavy metals generally exist in nature in natural concentrations, but due to the increasing mining, smelting, processing and commercial manufacturing activities of heavy metals by humans, many heavy metals such as lead, mercury, cadmium, cobalt, etc. have entered the atmosphere, water, and soil. cause serious environmental pollution. Heavy metals that exist in various chemical states or chemical forms will persist, accumulate and migrate after entering the environment or ecosystem, causing harm. Heavy metal pollution can sometimes cause great harm. Among them, lead and its compounds are toxic to various tissues of the human body. The harm of lead poisoning is mainly manifested in lifelong damage to the nervous system, blood system, cardiovascular system, and skeletal system. In general, lead poisoning can lead to kidney failure, inhibit brain development, especially in children, and cause multiple neurotoxic effects. Since lead is non-degradable, it persists in the environment and can produce It can be seen that the harm of lead poisoning is serious, so the prevention and detection work becomes very important. However, the symptoms of lead poisoning are often very hidden and difficult to be discovered, and these are all related to environmental deterioration. The lead emitted by automobile exhaust enters the environment through atmospheric diffusion and other processes, resulting in a significant increase in the current concentration of lead on the surface, resulting in a 100-fold increase in the amount of lead absorbed by modern humans compared to primitive humans, which has damaged human health. Therefore, it is of great significance to realize the real-time detection and in-situ rapid detection of heavy metal ions in the environmental field or in organisms.

The methods commonly used to determine the content of trace heavy metal ions are: atomic absorption spectrometry, which belongs to the conventional elemental analysis method, but has low sensitivity and complicated operation for the determination of trace elements. Zeeman effect graphite furnace atomic absorption spectrometry is an accurate and reliable method, but it is also complicated to operate and expensive, making it difficult to apply on a large scale. In addition, there is a method of colorimetric determination using a complexing agent and a colored complex with ions, but its sensitivity is low and its reproducibility is poor, so it is rarely used now. Fluorescent molecular probe technology is applied to the detection of transition metals and heavy metal ions, which can realize in situ detection. However, fluorescent probes usually have better detection results in organic solvents, but have certain limitations in aqueous solutions. In recent years, nucleic acid aptamers (aptamers) or DNA enzymes have been used as functional reagents to prepare probes with gold nanoparticles for the detection of heavy metal ions such as Pb ²⁺ [Wang Z D, Lee J H, Lu Y, Adv. Mater.2008, 20, 3263-3267; Liu J W, Lu Y, 2004, J.Am.Chem.Soc.2004, 126, 12298-12305; Liu, J W, Lu Y, 2004, Anal.Chem.76, 1627 -1632; Liu J W, Lu Y, J.Am.Chem.Soc.2005, 127, 12677-12683; Wei H, Li B L, Dong S J, Wang E K, 2008, 19, 095501.], can achieve better Sensitivity and selectivity, but due to the high cost of DNA and enzymes, it cannot be the choice for general application.

Aiming at the above problems, we studied a method to detect heavy metal ions using functionalized gold nanoparticle sol as a colorimetric device. The invention provides a method with simple and fast operation, which can realize rapid detection of heavy metal ions without the aid of instruments (colorimetric observation with naked eyes).

Contents of the invention

The purpose of the present invention is to provide a colorimetric detection probe capable of detecting heavy metal lead ions in aqueous solution.

Another object of the present invention is to provide an application method of a lead ion colorimetric detection probe in the detection of heavy metal ions.

The lead ion colorimetric detection probe of the present invention is glutathione (GSH) functionalized gold nanoparticles. Because the sulfhydryl group in its structure is easy to combine with gold nanoparticles, glutathione is used to modify gold nanoparticles to obtain glutathione functionalized gold nanoparticles GSH-GNPs, which contains two free carboxyl structures , glutathione functionalized gold nanoparticles can be a colorimetric probe for the detection of heavy metal ions. During the detection process, two free carboxyl groups can coordinate with heavy metal ions, and the trace heavy metal ions Pb ²⁺ contained in the aqueous solution can be detected through the colorimetric detection method by using the surface plasmon resonance properties of gold nanoparticles.

1. Synthetic method of colorimetric probe glutathione functionalized gold nanoparticles (GSH-GNPs):

At room temperature, according to the mass ratio of GSH and chloroauric acid two kinds of reactants is 3 ~ 6: 1 to form an aqueous solution, the two solutions are mixed under magnetic stirring, the solution changes from light yellow to white emulsion, with 0.5 ~ 1M/L NaOH solution to adjust the pH value of the mixed solution in the range of 6 to 8. During this process, the solution gradually becomes clear, and then reduced with 1 to 2 mg/mL newly prepared sodium borohydride ice water solution, and kept stirring for 10 to 24 hours, centrifuge to remove unreacted material, and then redisperse the gold particles in water to obtain the glutathione functionalized gold nanoparticles (GSH-GNPs) whose solution color is red, and the UV-visible spectrum is tested at 520nm. Characteristic absorption, glutathione functionalized gold nanoparticles are lead ion colorimetric detection probes.

2. Detection of lead ions (Pb ²⁺ )

1. Detection sensitivity

When using GSH-GNPs as a colorimetric detection probe to detect Pb ²⁺ , it has high sensitivity. Add an equal amount of the sample to be tested into the colorimetric probe solution diluted 2 to 5 times, and then add 1 to 2M NaCl solution accounting for 10% of the total volume of the solution. If there is no Pb ²⁺ in the sample to be tested, the ratio The red color of the color probe solution will remain unchanged. When the Pb ²⁺ content is greater than 5 μM, the color of the solution will change from red to purple or blue-gray. After 10 to 30 minutes (depending on the concentration of lead ions in the solution), colorimetric detection can be carried out by testing the ultraviolet-visible absorption spectrum of the solution. The absorption spectrum has a good linear relationship with the concentration of lead ions. The glutathione-functionalized gold nanoparticles can be used as a probe for detecting lead ions in aqueous solution to quickly detect the presence of lead ions, and the detection limit can reach 100nM.

2. Selectivity

The use of glutathione-functionalized gold nanoparticles as a colorimetric detection probe showed high selectivity for the detection of Pb ²⁺ . With Hg ²⁺ , Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Cu ²⁺ , Co ²⁺ , Ca ²⁺ , Mn ²⁺ , Fe ²⁺ , Mg ²⁺ , Cd ²⁺ and Ba ²⁺ When detecting and comparing, the colorimetric probe has very good selectivity to Pb ²⁺ . Under the same conditions, the concentration of Pb ²⁺ detected is higher than that of Hg ²⁺ , Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Cu ²⁺ , The concentrations of Co ²⁺ , Ca ²⁺ , Mn ²⁺ , Fe ²⁺ , Mg ²⁺ , Cd ²⁺ and Ba ²⁺ ions are 100-1000 times lower, indicating high selectivity.

The present invention has the following advantages:

1. The detection probe provided by the present invention has high sensitivity, good selectivity and low detection limit.

2. The test result can be identified by colorimetry (naked eye observation or ultraviolet spectrum) without the aid of an instrument.

3. The present invention is easy to prepare and preserve; it can be preserved for 6-12 months at 4°C.

4. The reagents and operating procedures used in the present invention have no toxic or side effects.

5. The method of the present invention is simple, fast, and easy to operate, does not require large-scale instruments, and can perform on-site rapid detection.

Description of drawings

Accompanying drawing 1, colorimetric probe detects the ultraviolet-visible absorption spectrum and colorimetric contrast photo of lead ion:

Among them, a is the absorption spectrum of the colorimetric probe and the corresponding photo of the solution; b is the absorption spectrum of the colorimetric probe solution after detecting lead ions and the corresponding photo of the solution.

Accompanying drawing 2, the linear relationship between the absorption ratio of the absorption spectrum and the initial concentration of lead ions (1-50 μM) after the colorimetric probe detects different concentrations of lead ions.

Detailed ways

Example 1:

At room temperature, the aqueous solution of chloroauric acid and glutathione are mixed and stirred to form an aqueous solution according to the mass ratio of 6:1, and the pH value of the mixed solution is adjusted to 7.0 with 1M sodium hydroxide solution, and then in the mixed solution Add the newly prepared sodium borohydride ice water solution (2mg/1mL) and stir vigorously. The mixed solution is continuously reacted for 12 hours under stirring conditions, centrifuged to remove unreacted substances and redispersed to obtain glutathione functionalized gold Nanoparticles, that is, colorimetric probes, measure their UV-Vis absorption spectrum, and have characteristic absorption at 520nm.

Example 2:

When using a colorimetric probe to detect lead ions, dilute the prepared colorimetric probe 4 times, take 100 μl of the diluted colorimetric probe solution and add it to the same amount of biological tissue or environmental sewage sample to be tested, and then add 20 μl , 1M NaCl solution, by observing the color change of the solution to judge whether there is the presence of lead ions, when there are lead ions, the solution changes from the red color of the gold particles to purple or blue-gray; or test the ultraviolet-visible absorption spectrum of the solution, the presence of lead ions , the ultraviolet-visible characteristic absorption spectrum of the solution is red-shifted, and the absorption spectrum has a good linear relationship with the concentration of lead ions, so as to judge whether there are lead ions in the sample to be tested.

Claims (2)

1. a lead ion colorimetric detection probe, it is characterized in that colorimetric probe is the gold nanoparticle of glutathione functionalization, and solution is deep red, and test ultraviolet-visible spectrum has characteristic absorption at 520nm place, encounters When the lead ion absorption spectrum red shifts, the color of the solution turns purple or blue-gray, and the probe is prepared by the following method: at room temperature, the aqueous solution of chloroauric acid and glutathione are 6: 1 by mass ratio Make an aqueous solution, mix and stir, and adjust the pH value of the mixed solution to 7.0 with 1M sodium hydroxide solution, then add the newly prepared sodium borohydride ice water solution 2mg/1mL to the mixed solution and stir vigorously, and the mixed solution is under stirring condition Continue to react for 12 hours, centrifuge to remove unreacted substances and redisperse. 2. an application method of the lead ion colorimetric detection probe that the method for claim 1 makes, its detection process is: use the gold nanoparticle of glutathione functionalization as detection probe to detect Pb2+, Add the same amount of biological tissue and environmental sewage samples to be tested into the colorimetric probe solution diluted 2-5 times, and then add 1-2M NaCl solution accounting for 10% of the total volume of the solution to change the ionic strength of the solution, Observe the color change of the mixed solution, or test its ultraviolet-visible absorption spectrum, and perform colorimetric detection. When lead ions exist, the color of the mixed solution changes from red to purple or blue gray of gold nanoparticles, or the ultraviolet-visible characteristics of the solution The absorption spectrum has a red shift, and the absorption spectrum has a good linear relationship with the ion concentration. The existence and concentration of lead ions can be determined by the shift of the color and absorption spectrum.

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