Direct Electrochemistry Of Proteins On Polypyrrole Nanotube Surface

Direct electrochemistry of proteins has drawn much attention in electrochemical field.Due to the electroactive center buried deeply inside the molecule，the direct electrontransfer between electrode surface and the protein is difficult to berealized.Nano-structured materials have special physical and chemical properties，caneasily load such macromolecules， promote the electron transfer between electrode surfaceand protein，and maintain biological activity of proteins. Electrochemical biosensors can beconstructed based on the direct chemistry of proteins.In this dissertation，polypyrrole nanotube（PPyNT）was used to immobilize severalproteins for preparation of carbon paste electrodes. These electrochemical systems canrealize the direct electrochemistry of proteins and can be used novel electrochemicalbiosensors，which proposed new strategies for biosensor constructions.（1） Hemoglobin（Hb） was immobilized on the surface of PPyNT to fabricateHb-polypyrrole nanotube carbon paste electrode （Hb/PPyNT/CPE）. The directelectrochemistry of Hb was realized. The results showed that PPyNT can promote theelectron transfer kinetics of between Hb and the electrode surface. The immobilized Hbcan maintain its bioactivity of the catalysis to the reduction of H₂O₂. The biosensor’sresponse sensitivity reaches0.249A M^-1，detection limit1.58×10^-7M. Linear calibrationrange covers from5.0×10^-5to2.0×10^-4M. The biosensor has good reproducibility andgood stability.（2）Glucose oxidase（GOD）was immobilized on the surface of PPyNT to fabricateGOD-polypyrrole nanotube carbon paste electrode（GOD/PPyNT/CPE）.The direct electrochemistry of GOD was realized. The results showed that PPyNT canpromote the electron transfer kinetics of between GOD and the electrode surface. Theimmobilized GOD can maintain its bioactivity of the catalysis to the oxidation of glucose.The biosensor’s response sensitivity reaches0.14A M^-1，detection limit1.58×10^-7M.Linear calibration range covers from1.25×10^-8to1.0×10^-7M. The biosensor has goodreproducibility and good stability.（3） Horseradish peroxidase（HRP）was immobilized on the surface of PPyNT tofabricate HRP-polypyrrole nanotube carbon paste electrode（HRP/PPyNT/CPE）.The direct electrochemistry of HRP was realized. The results showed that PPyNT canpromote the electron transfer kinetics of between HRP and the electrode surface. Theimmobilized HRP can maintain its bioactivity of the catalysis to the reduction of H₂O₂. Thebiosensor’s response sensitivity reaches0.268A M^-1，detection limit2.58×10^-7M.Linear calibration range covers from1.2×10^-5to1.5×10^-4M. The biosensor has goodreproducibility and good stability.