Research on direct electron transfer of native glucose oxidase at PEDOT:PSS hydrogels modified electrode

Direct electron transfer (DET) is the critical issue in developing the third-generation glucose biosensor. However, the DET of glucose oxidase (GOx) is hard to realize because the redox center of GOx is located deeply within the enzyme molecule. Here, we have studied DET of GOx on a poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) hydrogels decorated carbon nanotube fiber (CNTF) electrode with oxygen-independence glucose determination performance. PEDOT:PSS hydrogels modified on carbon nanotube fiber by electrogelation might play a key role in keeping the catalytic activity and DET for GOx simultaneously. The cyclic voltammetric result of the biosensor shows a pair of well-defined and quasi-reversible redox peaks with a formal potential of −0.431 V and a peak-to-peak separation of 69 mV. The constructed biosensor shows a linear range from 0.05 to 0.5 mM and a sensitivity of 43.52 μA mM−1 cm−2 toward glucose via a constant potential of −0.3 V in an N2-saturated solution. Three GOx models on the electrode surface are proposed to explain these DET-related electrochemical performances of the biosensor. We demonstrate the DET for the native GOx with catalytic activity in PEDOT:PSS hydrogels, which takes a step towards developing the third-generation glucose biosensor with conductive hydrogels.