Micro-droplet electrochemical sensor for detecting food-borne microorganisms and preparation method thereof

A microbial detection and electrochemical technology, which is applied in the field of chemical analysis, can solve the problems that the sensitivity needs to be improved and cannot meet the detection requirements of food-borne microorganisms, so as to avoid false positive detection, achieve signal stability, and simple production process.

Active Publication Date: 2019-08-30
UNIV OF SCI & TECH BEIJING
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Unfortunately, the sensitivity of these electrochemical sensors still needs to b

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  • Micro-droplet electrochemical sensor for detecting food-borne microorganisms and preparation method thereof
  • Micro-droplet electrochemical sensor for detecting food-borne microorganisms and preparation method thereof
  • Micro-droplet electrochemical sensor for detecting food-borne microorganisms and preparation method thereof

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Embodiment 1

[0082] 1. The first step of signal amplification system preparation: the first DNA walker is generated on streptavidin magnetic beads. Briefly, first react 4 μL of blocking DNA (1.5 μM) and 1 μL of first probe (1.5 μM) in sodium citrate (0.5 M / L) at 37 °C for 2 hours to form double-stranded DNA. Then, the obtained double-stranded DNA and 20 μL of the second probe (1.5 μM) were simultaneously added to 20 μL of 1 mg / mL streptavidin magnetic beads in phosphate-buffered saline solution. After reacting at room temperature for 2 hours, the magnetic bead system was obtained by magnetic separation for future use.

[0083] 2. Gold electrode preparation: ITO glass substrates (0.5 cm×2 cm) were sonicated in acetone, ethanol and ultrapure water for 30 minutes, and then dried with nitrogen. Titanium and gold are then sequentially sputtered onto the cleaned conductive side of the ITO. Using the ITO glass substrate as the working electrode, the Pt wire as the counter electrode and the Ag / A...

Embodiment 2

[0094] Dual DNA walker electrochemical sensor detects specific gene fragments of target Escherichia coli O157:H7:

[0095] (1) Detection principle: The design principle is described in detail in the scheme. This scheme is an electrochemical sensor based on a double DNA walker, which is used for the detection of specific gene fragments of target Escherichia coli O157:H7. The substrate preparation process is shown in the scheme. The superhydrophilic / superhydrophobic gold electrode includes: ITO conductive glass, base layer, nanostructured gold layer, and superhydrophobic surface from top to bottom. The superhydrophobic surface is provided with hydrophilic micropores. The base layer includes a titanium layer and a flat gold layer, which are all modified on the conductive side of the ITO conductive glass by magnetron sputtering, and then the nanostructured gold layer is modified on the flat gold layer by electrochemical deposition. Then superhydrophobic treatment is performed on t...

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Abstract

The invention belongs to the field of chemical analysis, in particular to a micro-droplet electrochemical sensor for detecting food-borne microorganisms and a preparation method thereof. Specific genefragments of the food-borne microorganisms are subjected to trace detection by a double-signal amplification system strategy to achieve signal amplification in the first step in the presence of a target gene fragment; a second DNA walker opens a third probe to form double-stranded DNA which is dissociated by a fourth probe modified with ferrocene at one end through two-strand displacement to release the DNA walker for use in the next cycle, thereby achieving signal amplification in the second step. According to the invention, the detection efficiency is improved by a double signal amplification technology, the signal stability is achieved, and the target escherichia coli O157:H7 specific gene fragment detection limit is reduced, the problems of the long period and complicated operation ofthe conventional detection of food-borne pathogens are solved; the detection accuracy is improved, and false positive detection is effectively avoided; and moreover, the electrochemical sensor has asimple production process and a wide application prospect.

Description

technical field [0001] The invention belongs to the field of chemical analysis, in particular to micro-droplets used for the detection of food-borne microorganisms in micro-droplets for the electrochemical detection of specific gene fragments of food-borne microorganism Escherichia coli O157:H7 by means of a double DNA walker strategy Electrochemical sensor and preparation method. Background technique [0002] Today, food quality issues have attracted widespread attention from consumers, the food industry and food safety inspection agencies. Foodborne microorganisms, which are a major threat to food safety, usually exist in various foods, such as vegetables, fruits and ready-to-eat products, which may cause human diseases and pose threats to human health. Therefore, accurate identification and detection of foodborne microorganisms becomes crucial. Plate count, polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) are routine, reliable and accurate m...

Claims

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Application Information

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IPC IPC(8): G01N27/327
CPCG01N27/3275
Inventor 许利苹张晓妍吴婷婷杨月萌
Owner UNIV OF SCI & TECH BEIJING
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