The Research Of Electrochemical Sensor For Antibiotics Determination Based On Body Conformation Chang Of Nucleic Acid

Antibiotics, as a kind of microbial metabolites, are widely used to kill or inhibit the growth of microorganisms. In recent years, antibiotics have been widely applied to treat of all kinds of virus infection disease, especially its application in animal husbandry and agriculture become more and more widely. Excessive and inappropriate use of antibiotics has led to its residue in food increases year by year. Long-term ingestion of food containing excessive amounts of antibiotics will cause antibiotics accumulate in the body, human will be resistant to antibiotics, it is harmful to humans' health. Nowadays, antibiotic residues in food has received great attention around the world, many countries have established a series of relevant index to the antibiotic biggest residues in food. But the existing traditional way to detect the antibiotics is limited to a variety of external and internal conditions. Therefore, it is urgent need to study a kind of high sensitivity, high selectivity of detection method of antibiotics residues in food. This paper, by using electrochemical sensing combined with nucleic acid adaptation of body conformation change detection of antibiotic residues in food biosensor was constructed. Build the sensor to measure the target of all showed a low detection limit and wide linear range, and has good selectivity and stability, in the actual sample testing also got good recovery rate.The main contents of this work were shown in the following:1. An RNA aptamer-based electrochemical biosensing strategy has been developed for sensitive and selective detection of malachite green(MG). This biosensor is fabricated by the self-assembly of a thiolated MG aptamer(MGA) on AuNPs/graphene–chitosan nanocomposite modified glass carbon electrode. When the modified electrode is incubated in the presence of MG, MGA combines specifically with MG, which causes the horseradish peroxidase(HRP)-labelled MG antibody close to the electrode surfaces. As a result, MG detection is realized by outputting a redox current from electro-reduction of the hydrogen peroxide reaction catalyzed by HRP. Differential pulse voltammetry(DPV) is performed to record the signal responses. The results reveal the biosensor displays a very low detection limit as low as 16.3 pg mL-1 and a wide linear range from 1×10-4 to 10 mg mL-1 of MG.Hence, this proposed RNA aptamer-based electrochemical strategy may offer a simple, rapid,costeffective, highly selective and sensitive method for the quantification of MG.2. In the work, we have developed a high specific and ultrasensitive electrochemical aptasensor by coupling the target-triggered structural change of programmable hairpin probes with the isothermal signal amplification strategy. To the best of our knowledge, this work is the first time that target-aptamer binding triggered quadratic recycling amplification has been utilized for electrochemical detection of antibiotics. Using the signal amplification strategy,the resulting electrochemical aptasensor can detect antibiotics AMP with excellent sensitivity,and the LOD can be as low as the attomole level. Moreover, our biosensing strategy offers the advantage of facilitated instrumentation, shortened analysis time, and simplified operations without the need of sample pretreatment and multiple washing steps. Hence, this biosensing strategy might provide a simple, rapid, and cost-effective electrochemical method for the determination of antibiotics in foodstuffs with high specificity and sensitivity. Additionally,the proposed strategy holds the potential of being extended for the detection of aptamer binding molecules and combined with other detection tools such as fluorescence assay.3. In the work, a signal-on electrochemical DNA sensor based on multiple amplification for ultrasensitive detection of antibiotics has been reported. In the presence of target, the ingeniously designed hairpin probe(HP1) is opened and the polymerase-assisted target recycling amplification is triggered, resulting in autonomous generation of secondary target. It is worth noting that the produced secondary target could not only hybridize with other HP1,but also displace the Helper from the electrode. Consequently, methylene blue labeled HP2 forms a “close” probe structure, and the increase of signal is monitored. The increasing current provides an ultrasensitive electrochemical detection for antibiotics down to 1.3 fM. To our best knowledge, such work is the first report about multiple recycling amplification combing with signal-on sensing strategy, which has been utilized for quantitative determination of antibiotics. It would be further used as a general strategy associated with more analytical techniques toward the detection of a wide spectrum of analytes. Thus, it holds great potential for the development of ultrasensitive biosensing platform for the applications in bioanalysis, disease diagnostics, and clinical biomedicine.