Portable microcystin detector and using method thereof
阅读说明：本技术 一种便携式微囊藻毒素检测仪及其使用方法 (Portable microcystin detector and using method thereof ) 是由 杜晓娇 陈芬 许欣 秦浩源 于 2020-06-03 设计创作，主要内容包括：本发明公开了一种便携式微囊藻毒素检测仪及其使用方法,该检测仪包括电脑客户端、微型工作站和三电极体系,微型工作站用于将三电极体系采集的检测信号传输给电脑客户端,三电极体系中的工作电极包括丝网印刷碳电极(SPCE)以及从内到外依次修饰在丝网印刷碳电极(SPCE)外侧的纳米碳化钛涂层、纳米金涂层和巯基修饰的微囊藻毒素涂层。该检测仪尺寸较小,便于携带,搭建步骤简单,可以在任何场合快速搭建相应的测试系统,实现微囊藻毒素的测试现场化；检测操作步骤简单,所检测的结果具有较宽的检测范围(10<Sup>-12</Sup>～10<Sup>-9</Sup>mol/L)和较低的检出限(10<Sup>-12</Sup>mol/L),且检测结果准确可靠。(The invention discloses a portable microcystin detector and a using method thereof, the detector comprises a computer client, a micro workstation and a three-electrode system, the micro workstation is used for transmitting detection signals acquired by the three-electrode system to the computer client, and working electrodes in the three-electrode system comprise a Screen Printing Carbon Electrode (SPCE), and a nano titanium carbide coating, a nano gold coating and a mercapto group modified microcystin coating which are sequentially modified on the outer side of the Screen Printing Carbon Electrode (SPCE) from inside to outside. The detector is small in size, convenient to carry and simple in construction steps, and a corresponding test system can be quickly constructed in any occasion to realize the field test of the microcystins; the detection operation steps are simple, and the detected result has a wider detection range (10) ‑12 ～10 ‑9 mol/L) and a lower detection limit (10) ‑12 mol/L) and the detection result is accurate and reliable.)
1. A portable microcystin detector is characterized by comprising a computer client, a micro workstation and a three-electrode system, wherein the computer client is in signal connection with the three-electrode system through the micro workstation and is used for transmitting detection signals acquired by the three-electrode system to the computer client, and working electrodes in the three-electrode system comprise a Screen Printing Carbon Electrode (SPCE), and a nano titanium carbide coating, a nano gold coating and a mercapto-modified microcystin coating which are sequentially modified on the outer side of the Screen Printing Carbon Electrode (SPCE) from inside to outside.
2. A method of making a working electrode according to claim 1, comprising the steps of:
s1: modifying a nano titanium carbide coating on the outer surface of a Screen Printing Carbon Electrode (SPCE) by using a spin coating method to form Ti3C2a/SPCE electrode;
s2: ti prepared at step S1 by electrochemical deposition3C2The outer surface of the/SPCE electrode is decorated with a layer of nano-gold coating to form Au/Ti3C2a/SPCE electrode;
s3: Au/Ti prepared at step S23C2And dripping a sulfydryl modified microcystin coating on the outer surface of the/SPCE electrode to obtain the working electrode, wherein the microcystin coating is a microcystin-LR (MC-LR) coating or a microcystin-RR (MC-RR) coating.
3. The method of claim 2, wherein in step S2, the electrochemical deposition method is a current-time curve method, wherein the voltage is 0.4-0.6V, and the operation time is 600-1500S.
4. The method for preparing the working electrode according to claim 3, wherein in step S3, the specific operations are as follows: dropwise coating the thiol-modified microcystin aptamer solution with the concentration of 3-5 mu mol/L on the Au/Ti prepared in the step S23C2Reacting the outer surface of the/SPCE electrode at room temperature for 3-5 h to obtain a working electrode crude product; and then, dripping 6-mercaptoethanol solution with the concentration of 1-3 mmol/L on the outer surface of the crude product of the working electrode, reacting for 1 hour at room temperature, and sealing redundant active sites on the outer surface of the nano gold coating to obtain the working electrode.
5. A use method of a portable microcystin detector is characterized by comprising the following steps:
w1: preparing, namely inserting a micro workstation on a computer client, connecting a three-electrode system with the micro workstation by signals to form a detection system, and preparing a blank control solution and a series of microcystin solutions with different concentrations;
w2: establishing a standard curve, placing a three-electrode system in a blank control solution, collecting an impedance spectrum of the blank control solution, then respectively placing the three-electrode system in microcystin solutions with different concentrations for warm bath for 20-40 min, collecting corresponding impedance spectra, and performing data analysis processing to obtain an impedance linear standard curve related to the microcystin concentration;
w3: and (3) detection application, namely placing the three-electrode system in a sample to be detected, measuring a corresponding impedance value, and comparing the impedance value with the impedance linear standard curve in the step W2 to obtain the concentration of the microcystin in the corresponding sample.
6. The method of claim 5, wherein in step W2, the solvent and the blank solution in the microcystin solutions of different concentrations are buffer solutions consisting of 0.1mol/L potassium chloride, 5mmol/L potassium ferricyanide, 5mmol/L potassium ferrocyanide, and 100mmol/L phosphoric acid, the test frequency is 0.01-10 kHz, and the potential is 0.23-0.24V.
Technical Field
The invention relates to the technical field of microcystin detection, in particular to a portable microcystin detector and a using method thereof.
Background
The middle and lower reaches of Yangtze river are one of the areas where fresh water lakes are intensively distributed in China, and in the past decades, human activities have great influence on the ecological systems of lakes in local areas, and most prominently, the increasingly eutrophication of suburban lakes. The lakes, reservoirs and rivers receive excessive nutrient substances such as nitrogen, phosphorus and the like, so that the ecological structure and the function of the water body are changed, and the phenomenon of cyanobacterial bloom is caused by the abnormal propagation and growth of algae, particularly cyanobacterial algae. The frequent occurrence of the algal bloom has become a general environmental concern as the eutrophication of water bodies has progressed. When the cyanobacterial bloom is serious, the sense organ of people is influenced, the healthy and balanced aquatic ecosystem is damaged, and the safety of drinking water of people and animals is seriously threatened by various algal toxins released after the algal cells are broken. Among the various phycotoxins found, microcystin is currently known as one which has the highest frequency, the highest production and the most serious harm in cyanobacterial bloom pollution, so the detection of microcystin is necessary.
The existing method for detecting microcystins mainly comprises an immunological detection method and a chemical analysis method, wherein the immunological detection method comprises a Protein Phosphatase Inhibition Assay (PPIA) and an enzyme-linked immunoassay (ELISA); the chemical analysis method includes High Performance Liquid Chromatography (HPLC), Mass Spectrometry (MS), fluorescence spectrometry (FL), ultraviolet spectrometry (UV), or chemiluminescence detection (CL). Among them, Protein Phosphatase Inhibition Assay (PPIA) and enzyme-linked immunoassay (ELISA) belong to biochemical analysis methods, such methods realize the detection of microcystins mainly through the specific recognition of biological antigen-antibody, and inevitably require the use of biological components such as antigen, antibody and the like which have higher requirements on the operating environment, so the operating conditions are severe and complex, and the cost is higher; although chemical analysis methods such as High Performance Liquid Chromatography (HPLC), Mass Spectrometry (MS), fluorescence spectroscopy (FL), ultraviolet spectroscopy (UV), or chemiluminescence detection method (CL) can satisfy the requirement of simultaneous detection of multiple toxins, their application is limited by instruments and devices, and laboratory analysis work can only be performed, and their detection cost is high, and the requirement on the quality of operators is high. Therefore, there is an urgent need to develop a new method for detecting microcystins to meet the practical requirements of low cost, portability and on-site microcystins monitoring.
Among various detection methods, the electrochemical sensor has the advantages of high sensitivity, simple and rapid operation, uninterrupted monitoring in a real complex environment system and the like, and has been widely applied in various fields. Among them, electrochemical alternating current impedance spectroscopy (EIS) has become an important means for studying electrode materials and electrode surface phenomena as a typical electrochemical analysis means. In addition, with the rapid development of electronic technology, miniaturization of electrochemical workstations has been primarily achieved, which has prompted the emergence of portable electrochemical sensing devices.
Over the past few years, screen printing techniques have made great progress in rapid manufacturing and low cost manufacturing. The screen printing electrode (SPCE) has the advantages of good repeatability, high reliability, convenient use and the like, and has wide application prospect in electrochemical analysis. SPCE offers electrochemical sensors an opportunity to be far from centralized laboratories due to its advantages of portability and inexpensive manufacturing techniques, providing conditions for the construction of disposable sensors. The disposable sensor has the advantages of low cost, batch production and good reproducibility, thereby ensuring that the detection result is more accurate and reliable. However, SPCE has not been studied as a working electrode of an electrochemical biosensor, and its sensitivity, stability and reproducibility have a certain margin, and for example, studies on modification and modification of its surface are closely related to its detection performance. Therefore, there is a need to further develop new electrode modification materials to further improve the performance of SPCE as a working electrode in electrochemical sensors.
The invention aims to combine a screen printing electrode with an electrochemical alternating-current impedance spectroscopy, and provides a portable microcystin detector and a using method thereof, so as to solve the problems and the defects in the microcystin detection technology.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a portable microcystin detector and a using method thereofA corresponding test system can be quickly set up in any occasion to realize the field test of the microcystins; the operation steps are simple, no strict requirements are imposed on the quality of operators, and the feasibility of on-site detection of the microcystins is ensured; the portable microcystin detector has a wider detection range (10)-12～10-9mol/L) and a lower detection limit (10)-12mol/L) and the detection result is accurate and reliable, so that the detector has wide application prospect in the fields of environmental analysis and food safety detection.
In order to achieve the purpose, the technical scheme of the invention is to design a portable microcystin detector which comprises a computer client, a micro workstation and a three-electrode system, wherein the computer client is in signal connection with the three-electrode system through the micro workstation and is used for transmitting detection signals acquired by the three-electrode system to the computer client, and working electrodes in the three-electrode system comprise a Screen Printing Carbon Electrode (SPCE), and a nano titanium carbide coating, a nano gold coating and a mercapto group modified microcystin coating which are sequentially modified on the outer side of the Screen Printing Carbon Electrode (SPCE) from inside to outside.
In order to facilitate the smooth preparation of the portable microcystin detector, a preparation method of the working electrode is provided, and the preparation method of the working electrode comprises the following steps:
s1: modifying a nano titanium carbide coating on the outer surface of a Screen Printing Carbon Electrode (SPCE) by using a spin coating method to form Ti3C2a/SPCE electrode;
s2: ti prepared at step S1 by electrochemical deposition3C2The outer surface of the/SPCE electrode is decorated with a layer of nano-gold coating to form Au/Ti3C2a/SPCE electrode;
s3: Au/Ti prepared at step S23C2And dripping a sulfydryl modified microcystin coating on the outer surface of the/SPCE electrode to obtain the working electrode, wherein the microcystin coating is a microcystin-LR coating or a microcystin-RR coating.
In the preferred technical scheme, in the step S2, the electrochemical deposition method specifically adopts a current-time curve method, wherein the voltage is 0.4-0.6V, and the operation time is 600-1500S.
Further preferably, in step S3, the specific operations include: dropwise coating the thiol-modified microcystin aptamer solution with the concentration of 3-5 mu mol/L on the Au/Ti prepared in the step S23C2Reacting the outer surface of the/SPCE electrode at room temperature for 3-5 h to obtain a working electrode crude product; and then, dripping 6-mercaptoethanol solution with the concentration of 1-3 mmol/L on the outer surface of the crude product of the working electrode, reacting for 1 hour at room temperature, and sealing redundant active sites on the outer surface of the nano gold coating to obtain the working electrode.
In order to facilitate the successful application and implementation of the portable microcystin detector, a use method of the portable microcystin detector is provided, which comprises the following steps:
w1: preparing, namely inserting a micro workstation on a computer client, connecting a three-electrode system with the micro workstation by signals to form a detection system, and preparing a blank control solution and a series of microcystin solutions with different concentrations;
w2: establishing a standard curve, placing a three-electrode system in a blank control solution, collecting an impedance spectrum of the blank control solution, then respectively placing the three-electrode system in microcystin solutions with different concentrations for warm bath for 20-40 min, collecting corresponding impedance spectra, and performing data analysis processing to obtain an impedance linear standard curve related to the microcystin concentration;
w3: and (3) detection application, namely placing the three-electrode system in a sample to be detected, measuring a corresponding impedance value, and comparing the impedance value with the impedance linear standard curve in the step W2 to obtain the concentration of the microcystin in the corresponding sample.
In the step W2, the solvent and the blank control solution in the microcystin solutions with different concentrations are buffer solutions composed of 0.1mol/L potassium chloride, 5mmol/L potassium ferricyanide, 5mmol/L potassium ferrocyanide and 100mmol/L phosphoric acid, the test frequency is 0.01-10 kHz, and the potential is 0.23-0.24V.
The invention has the advantages and beneficial effects that:
1. the portable microcystin detector is small in size, convenient to carry and simple in construction steps, so that a corresponding test system can be quickly constructed in any occasion, and the test of microcystin is realized on site.
2. The invention relates to a portable microcystin detector, because the outer surface of a substrate (screen printing carbon electrode) of a working electrode is provided with a sensitive material Au/Ti3C2，Au/Ti3C2Not only is a good carrier of the microcystin aptamer, but also plays a role in signal amplification, so that the portable microcystin detector has a wider detection range (10)-12～10-9mol/L) and a lower detection limit (10)-12mol/L) and has wide application prospect in the fields of environmental analysis and food safety detection.
3. The portable microcystin detector has simple components, is easy to obtain, and particularly comprises a working electrode, wherein the substrate of the working electrode is a screen printing carbon electrode which has the advantages of low manufacturing cost, good repeatability, high reliability, accurate and reliable detection result and the like, so that the working electrode is suitable for large-scale production and popularization in field detection.
4. The use method of the portable microcystin detector has simple operation steps, has no strict requirements on the quality of operators, and ensures the feasibility of on-site detection of microcystin.
Drawings
FIG. 1 is a schematic structural diagram of a portable microcystin detector of the present invention;
FIG. 2 is an impedance profile of microcystin-LR at different concentrations in example 5;
FIG. 3 is a graph of standard linear curves of different concentrations of microcystin-LR and corresponding impedance values in example 5.
In the figure: 1. a computer client; 2. a mini-workstation; 3. a working electrode; 4. a reference electrode; 5. a counter electrode.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.