Electrochemical Biosensor Based On Tin Dioxide Nanocomposite For Organophosphorus Pesticide Detection

Organophosphate pesticides are the most commonly applied pesticides that are essential for crop growth and storage because of their high efficiency and long-residue.However,the widespread and excessive use of pesticides can lead to long-term residues in the environment,causing serious harm to public health and food safety.Therefore,it is essential to develop affordable,sensitive and real-time pesticide detection techniques.In recent years,ACh E-based electrochemical biosensors have developed rapidly due to their advantages of high sensitivity,short detection period and instrumental simplicity.The design and preparation of electrode modification materials with excellent performance for the construction of electrochemical biosensors has become one of the research hotspots in the field of sensing.In this paper,two kinds of nanocomposites with excellent electrochemical performance were prepared by combining tin dioxide nanomaterials with other materials,and a sensitive and efficient electrochemical detection platform for organophosphorus pesticides was constructed.The main contents of the study are as follows:（1）A sensitive electrochemical acetylcholinesterase biosensor based on amino modified ultra-thin carbon layer tin dioxide nanosheets（SnO₂@C-A NSs）heterogeneous material was synthesized by a simple hydrothermal method for the detection of organophosphorus pesticides.Interestingly,the obtained amino-functionalized SnO₂@C NSs（SnO₂@C-A NSs）not only possess excellent catalytic activity,but also can offer an extremely hydrophilic surface as well as a suitable microenvironment for ACh E loading,enabling effective enhancement of the sensitivity of the biosensor.The results demonstrate that the electrochemical biosensor based on SnO₂@C-A NSs has realized an ultrasensitive electrochemical performance for methamidophos analysis with the wide linear range of4.5×10^-13 M-4.5×10^-7 M and the relatively low detection limit of 2.5×10^-14 M.（2）The 5 mol%Co₃O₄/SnO₂/PANI nanocomposites with multi-layer flower-like structure were synthesized by hydrothermal method and in-situ polymerization.The material was analyzed through morphology and structure characterization as well as electrochemical tests,indicating that the synthetic composite materials not only offers a suitable matrix for immobilization of acetylcholinesterase,but also possess excellent conductivity and catalytic activity.The electrochemical biosensor with a wider linear range(4.5×10^-13 M-4.5×10^-7 M),and a relatively lower detection limit(1.3×10^-14 M)based on 5 mol%Co₃O₄/SnO₂/PANI was constructed to detect dichlorvos.