Investigation On Novel Aptamer-based Electrochemical Sensors

In recent years,food safety issues have become more frequent,constantly bringing new challenges to people.Therefore,research topics in the field of food safety testing have become one of the hot spots of public concern.Most of the traditional food safety analysis methods are complicated in pre-processing,expensive,and real-time detection of samples cannot be realized.The nucleic acid aptamer electrochemical sensor has the advantages of good affinity,high selectivity and high sensitivity,so it has good development potential and wide application prospects in food safety testing.This study is aimed at the shortcomings of the slow response of traditional electrochemical sensors in actual detection.The adenosine triphosphate disodium salt?ATP?and kanamycin molecules are used as target analytes which by changing the structural configuration and complexation of nucleic acid aptamers.In the process of needle binding reaction,a"sandwich type"fragment nucleic acid aptamer and a"one-step competitive"nucleic acid aptamer probe which can rapidly detect a target molecule are obtained.The new electrochemical sensor constructed on this basis exhibits high sensitivity and response speed to the target molecule,and has good selectivity and specificity,and finally obtains a good recovery rate in the actual sample detection.The main research contents and results of the thesis include:Design of nucleic acid aptamer fragment probe electrochemical sensor and application of ATP detection.Although the replacement nucleic acid aptamer electrochemical sensor has a wide range of applications,in the actual sample detection,the hybridization time of the aptamer chain and the complementary strand of the nucleic acid is long,which limits the rapid recognition of the target molecule by the aptamer,thereby causing the actual detection of the short response time is short,while the traditional"sandwich"electrochemical sensor has a fast response,but has limited sensitivity to target molecule detection.Therefore,the second part of the paper is based on the traditional"sandwich"nucleic acid aptamer probe,subtly dividing a complete nucleic acid aptamer chain into two fragments,so that the background signal of the sensor is significantly reduced when the target molecule appears,it can quickly form a"sandwich type"composite structure,thereby obtaining an electrochemical sensor with high sensitivity and fast response speed.Subsequent experiments explored the concentration of the aptamer chain,the frequency of measurement,the concentration of Mg²⁺in the test solution,and the effect of detection time on the signal gain of the sensor.Finally,under the optimal conditions,the linear equation of the sensor for detecting ATP molecules is SI/%=5.9610×[ATP]/?M-33.1696?R²=0.9967,SI:signal increase?,the detection range is 0.5⁸00?M,the detection time is 2 min.Design of one-step competitive nucleic acid aptamer electrochemical sensor and detection application of kanamycin.The overuse of antibiotics today has caused serious harm to society,and kanamycin residues in foods may cause resistance to antibiotics in bacteria,thus endangering people's lives.Traditional methods for detecting kanamycin residues are time consuming,expensive,and require complex experimental equipment.As the aptamers of kanamycin are screened out and the aptamers of kanamycin are screened,the replacement pair The stranded nucleic acid aptamer probe is one of the most widely used signal conversion methods.Although the sensor has achieved high sensitivity,there is still a problem that the detection time is too long.In this experiment,a one-step competitive sensor was designed with kanamycin as the target analyte,and the complementary strand and the target molecule were simultaneously added,so that the hybridization of the aptamer and the complementary strand were not allowed,which greatly reduced the detection time and shortened the experimental procedure.In order to obtain higher sensitivity,the experiment also optimized the concentration of the complementary strand,the frequency of SWV measurement,the concentration of salt ions in the test solution,and the pH value,and examined the detection performance of the sensor on kanamycin in detail.Finally,under the optimal conditions,under the optimal conditions,the linear equation of the sensor for the detection of kanamycin molecules is SI/%=0.7723×[Kan]/?M+8.7895?R²=0.9963?.The range is 0.5⁷5?M,the detection time is 2 min.