Preparation Of Temperature Sensitive Electrochenical Sensors And Application In Drug Analysis

With the development of society,people’s demand for a better life continues to grow,and medication and food safety are receiving more and more attention.However,when detecting and analyzing drugs in complex matrix samples such as blood and food,there are problems such as low concentration of analytes and excessive interfering substances,which often require complex sample pretreatment processes.Electrochemical sensors have made rapid progress in the field of rapid detection due to their outstanding advantages such as high sensitivity,good selectivity,simple operation,low cost,and the ability to simplify pretreatment processes.Thermosensitive polymers can undergo a reversible phase transition of stretching and contracting of their chain segment structure by changing the temperature mear the transition temperature.They are a highly promising intelligent material,but have the disadvantage of poor conductivity.Nanomaterials are widely used in the field of electrochemical sensors due to their unique physical and chemical properties,such as strong conductivity and large specific surface area.Therefore,This research coostructs modified electrodes by combining thermosensitive polymers with nanomaterials,which endows the sensor with intelligent interface temperature control and is used for actual sample detection,enriching new research directions in electrochemical sensing.The main content is as follows:(1)A temperature sensitivc polymer poly(N-isopropylacrylamide)(PNIPAM)was synthesized through free radical polymerization.Compounded with carboxylated multi walled carbon nanotubes(MWCNTs(COOH)),the polymer has good conductivity to construct an electrochemical sensor with temperature response characteristics for dopamine(DA)detection.When the temperature is at room temperature,the PNIPAM chain segments extend.The thickness of the composite film increases,while hindering the transfer of electrons,to inhibit the redox reaction of DA.The peak current value is small.Currently,the sensor is in the "OFF" state.When the temperature is at 40℃,the PNIPAM chain segment shrinks.The composite film thickness decreases.The electron transfer rate accelerates,and the peak current value increases.The electrochemical sensor has excellent detection performance for DA when the sensor is in the"ON" state at this time.In addition,in the "ON" state,PNIPAM/MWCNTs(COOH)/GCE has a wide detection range(0.5-150 μM),low detection limit(0.193 μM)and with good stability for DA detecting,it can be used for the detection of DA in serum.(2)A temperature sensitive polymer N-isopropylacrylamide-co-N-tert butyl acrylamide P(NIPAM-co-NTBA)was synthesized through random copolymerization,while ZnO/CuO was prepared through a one-step hydrothermal method.P(NIPAM-co-NTBA),MWCNTs(COOH),and ZnO/CuO were combined to construct an electrochemical sensor with temperature "zipper switch" characteristics for detection of gallic acid(GA).When the temperature is at 36℃,the prepared sensor is in the "ON" state and has a significant electrochemical response to GA.When the temperature is at 22℃,the thickness of the prepared composite film increases.The electrochemical sensor is in the "OFF" state,resulting in weaker electrochemical response to GA.Meanwhile,when in the "ON" state,the sensor has a wide detection range(5-49.9 μM and 49.9788.4 μM),low detection limit(1.96 μM),good repeatability and reproducibility,which can be used for the detection of GA in tea.(3)Cu nanoparticles were loaded on MWCNTs(COOH)by a simple chemical reduction method to obtain Cu-MWCNTs(COOH),which were compounded with P(NIPAM-co-NTBA)by ultrasound to prepare a composite modified electrode for detection of rutin.When the temperature is at 22℃,the polymer segment extends,hindering the electron transfer between rutin molecules and the electrode surface.The electrochemical sensor is in the "OFF" state.When the temperature is at 36℃,the electron transfer rate between rutin molecules and the electrode accelerates,and the electrochemical sensor is in an "ON" state.In addition,in the "ON" state,the electrochemical sensor has good detection performance for rutin,with a detection range of 0.217 μM,detection limit is 0.113 μM.It can be used for the detection of rutin content in rutin tablets.