Construction And Application Of Nanomaterials-Aptamer Electrochemical Sensor

Emerging pollutants such as phenolic endocrine disruptors and antibiotics are great threats for ecological environment and human health,so it is of important significance to develop rapid detection methods.In recent years,nanomaterials have been widely used as modification materials for sensors due to their large specific surface area,strong electrical conductivity and good biocompatibility,and aptamers are often used as recognition materials for sensors due to their excellent specificity,low cost and wide range of targets.In this paper,two electrochemical sensors were developed for the detection of bisphenol A and tetracycline respectively by combining the strong conductivity of nanomaterials with high specificity of aptamers.The main research contents and results are as follows:A gold nanoparticles-aptamer electrochemical sensor was prepared for the detection of bisphenol A.Gold nanoparticles were deposited on the surface of glassy carbon electrode by potentiostatic deposition to improve the specific surface area and electrical conductivity of the electrode and the bisphenol A aptamer that can specifically bind bisphenol A was immobilized onto on the modified electrode surface through the interaction between Au-S bond.Using[Fe(CN)6]3-/4-as a redox probe,the detection performance of gold nanoparticles-aptamer electrochemical sensor was investigated by electrochemical impedance spectroscopy,and the factors affecting the sensor performance were optimized.When the deposition time of gold nanoparticles was 400 s,the concentration of aptamer was 1 μmol·L-1,the enrichment time was40 min at solution p H of 7.0,there was a good linear relationship between the impedance response and bisphenol A concentrations ranging from 1×10-9 to 5×10-6 mol·L-1,and the limit of detection(LOD)was 8.5×10-10 mol·L-1.The developed nanomaterials-aptamer electrochemical sensor has good selectivity,reproducibility and stability,and was applied to the detection of bisphenol A in environmental water samples with recoveries of 87.4-110%.A MXene-aptamer electrochemical sensor for tetracycline detection was developed based on MXene nanomaterials and tetracycline aptamer.β-mercaptoethylamine was fixed on the gold nano-modified electrode,and MXene was introduced on the surface of β-mercaptoethylamine modified electrode by self-assembly method.Then gold nanoparticles were electrodeposited,and tetracycline aptamer was modified on the electrode surface by AuS bond interaction.The influencing factors of the electrode preparation and detection process were optimized.Results showed that the optimal time of MXene assembly was 6,the enrichment time of tetracycline was 30 min,and the p H of the detected solution was 7.0.Under the optimized conditions,the response performance of the electrochemical sensor was studied.The electrode impedance response showed a good linear relationship with tetracycline concentration in the range of 1×10-11-1×10-6 mol·L-1,and the limit of detection(LOD)was9.5×10-12 mol·L-1.The developed sensor can detect tetracycline in environmental water samples with a recovery rate of 90-118%,and has good selectivity,stability and reproducibility.