Research Of H₂O₂ Electrochemical Biosensor Based On CeO_2-x-CNTs Composite Membrane

Excessive production of reactive oxygen species(ROS)can lead to various vital diseases such as Cancer,Neurodegenerative diseases and Ischemia-reperfusion damage,etc.Traditional biological analysis of ROS,mostly based on separate procedure of capture,labelling,and spectrometric detection process.However,these analytical methods were highly limited by its the short lifespan(microseconds to milliseconds),strong activity and low steady state concentration of ROS and thus a real-time and quantitative analysis detection method was in urgent need.In the thesis,the CeO_2-x-CNTs based flexible ROS sensor was systematically researched,optimized and utilized for the real-time detection of hydrogen dioxide(in lab)and total ROS(in sweat),respectively.The main research contents are as follows:(1)First,CeO_2-x-CNTs fabricated by one-step hydrothermal method.The morphological properties were studied by SEM,TEM,etc.CeO_2-x-CNTs/GCE was fabricated by drop-coating CeO_2-x-CNTs composite and Nafion solution onto glassy carbon electrode(GCE),and its electrochemical properties were studied by Cyclic voltammetry(CV),Electrochemical impedance spectroscopy(EIS)and Amperometric(i-t).Amperometric results of CeO_2-x-CNTs/GCE for hydrogen dioxide have shown linear response in wide detection range of 0.01 to 8 mM,limit of detection(LOD)of 0.52?M,sensitivity of 229.58?A·mM^-1·cm^-2.(2)Afterwards,the CeO_2-x-CNTs based flexible ROS sensor(CCFRS)was fabricated by direct screen-printing CeO_2-x-CNTs-based paste on a flexible polyethylene glycol terephthalate(PET)substrate and sealing unreactive part in polyimide film.Amperometric results of CCFRS for hydrogen dioxide have shown linear response in wide detection range of 0.01 to 10 mM,limit of detection(LOD)of 1.85?M,sensitivity of 136.59?A·mM^-1·cm^-2.Both CeO_2-x-CNTs/GCE and CCFRS exhibit superior performance over most recently reported H₂O₂ sensors.(3)Finally,the CeO_2-x-CNTs based flexible ROS sensor CCFRS device was successfully applied to detect the instant ROS in the sweat of adult men,the results had shown that the amperometric response could arise 8 times after half an hour strenuous exercise,which might be ascribe to intensive mitochondria activity and adenosine triphosphate(ATP),resulting in a dramatic increase in ROS concentration in the body.Moreover,cytotoxicity of the device components(PET and PI)and sensing materials(CeO₂?MWCNTs and CeO_2-x-CNTs)were systematically investigated by routine MTT assay,and the results confirmed the biosafety of CCFRS.The flexibility test results showed that the flexibility of the CCFRS was improved after CeO_2-x-CNTs and PI are loaded on PET.The above provides sufficient data support for the future wearable applications of CCFRS.All in all,the CeO_2-x-CNTs based flexible ROS sensor(CCFRS)provides an applicable and translational approach for the future rapid,real-time and easy detection of ROS.