Study On Fabrication And Application Of Sulfanilamide And Penicillin Impedance Sensors Based On Double-aptamer

In recent years,drug contamination of tap water caused by misusing and waste water discharge from pharmaceutical factories has occasionally occurred.As a non-mandatory testing index for domestic water with no relevant standards issued,accidental contamination of various drugs has brought unpredictable factors and big difficulty in preventive detection to drinking water safety,directly affecting people’s physical and mental health.It is necessary to establish simple and effective analytical techniques for the timely monitoring of occasional water pollution issues.Real-time on-line microdevice technology is an important development direction to meet this monitoring requirement.The combination of electrochemical measurement and aptamer technology opens up a new way for the development of this microdevice technology.Among electrochemical methods,impedance spectroscopy is often used as the preferred measuring technology.It is feasible with a lot of advantages of low cost,easy operation,high sensitivity,direct display and fast speed,which can better meets the requirements of microdevice detection parameters.The establishment of conventional aptamer electrochemical detection methods generally uses single aptamer sequence as the recognition probe.From the point of view of impedance generation principle,multiple aptamer sequences have more binding sites,which is expected to acquire high impedance value helpful to improve the method sensitivity.Following this idea,this paper introduced the aptamer docking editing technology into the sensor fabrication design and established two impedance spectrum analysis methods based on the aptamer-target(antibiotic molecule)interaction system.The aim is to provide candidate method resources for the new technology development and explore the possibility of domestic water application detection.Two impedance sensing methods were established for the determination of sulfadimethazine(SMD)and penicillin(PEN)in tap water respectively.The molecular simulation technology was used to comparatively reveal the molecular interaction mechanism of two single or double-aptamer/target complex systems.Electrochemical measurement methods were applied to characterize the sensing process and optimize its influencing parameters,and the comprehensive analytical performance was also investigated systematically.The research results show that docking double-aptamer has more binding sites than single aptamer,which is helpful to acquire higher resistance value.Two sequence docking ways,inverse-D-5T-SMD and cis-D-5T-PEN,are most stable for SMD and PEN system respectively.Under the optimal conditions,when applied for the detection of SMD and PEN in practical tap water samples,two proposed methods both showed good analytical performances with the linear range of 10.0 p M-10.0 n M and 1.0 p M-100.0 n M,the detection limit of 3.4 p M and 0.3 p M,and the signal response equilibrium time of ～20 min.When the method was validated as a quantitative analysis method,the mean standard recoveries were 77.0-85.4% and 79.8-92.1%with the relative standard deviation(RSD)<20%.All detection process can be finished within 60 minutes.The method performs excellently in analyzing speed,sensitivity and operability,having the potential as the candidate detection strategy methods of real-time on-line microdevice technology.