Construction Of The Nonenzymatic Sensors With Functionalized Carbon Nanotubes And The Detection For Releasing Of Superoxide Anion Radical From Cells

Considering the crucial roles of superoxide anion(O₂^·-)in pathological conditions,it is of great urgency to establish a reliable approach for real-time determination of O₂^·-.Among the current detection methods,electrochemical technique is considered as one of the most promising strategies due to its simplicity,fast response,low detection limit,and easy to use.This dissertation focused on the study of the nonenzymatic superoxide anion sensors based on carbon nanotubes and metal nanoparticles?NPs?.And the application for detection of O₂^·-in cancer cells was also investigated.The main contents were summarized as follows:1.A sensitive non-enzymatic sensor was constructed based on silver nanoparticles?AgNPs?and sodium dodecyl sulfate functionalized carbon nanotubes?SDS-MWCNTs?composites to measure the release of O₂^·-from cells.As an analytical and sensing platform,the AgNPs/SDS-MWCNTs modified glassy carbon electrode exhibited excellent electrochemical performance toward O₂^·-with a determination limit as low as 0.0897 nM and wide linear range of 6 orders of magnitude,which was superior to other O₂^·-electrochemical sensors.The excellent performance was attributed to the SDS-MWCNTs composites being used as effective load matrix for the deposition of AgNPs.Importantly,this novel non-enzymatic sensor could be applied to determination of O₂^·-released from cells,and the amount of flux of O₂^·-increased accordingly with the improving of the concentration of AA,which has the possibility of application in clinical diagnostics to assess oxidative stress of cells.2.Based on the first chapter,we used one-pot synthesis method to synthesize AgNPs/MWNTs nanocomposites,which were modified on the glassy carbon electrode to make the non-enzymatic O₂^·-sensor.In the presence of functionalized multi-wall carbon nanotubes?MWCNTs?,silver nanoparticles?AgNPs?were in situ generated by chemical reduction of silver nitrate with glucose as a reducing and stabilizing agent to give the desired AgNPs/MWCNTs nanocomposites.The characterization of nanocomposites was investigated employing scanning electron microscopy?SEM?,energy-dispersive X-ray spectrometer?EDS?,X-ray diffraction?XRD?and cyclic voltammetry?CV?.The resulted sensor exhibited favorable electrochemical performance for O₂^·-sensing with a low detection limit of 0.1192 nM and wide linear range of 6 orders of magnitude,which guarantees the capacity of sensitive and credible detection of O₂^·-released from cells.Moreover,we probe the ability to resist oxidative stress in a cell biological milieu under different intensity stimulations,experiment result indicated the capacity of cells to resist oxidative stress is limited.Thus,this work has great potential for further applications in biological researches.