Fabrication of PEDOT nanowhiskers for electrical connection of the hemoglobin active center for H2O2 electrochemical biosensing

Abstract

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanowhiskers were fabricated in a [bmim][BF₄] ionic liquid. The minimal size of the nanowhiskers is only 0.2 nm, and the size matches the thickness of a PEDOT single-molecular chain. They were successfully used as the electron transfer channels between the active center of hemoglobin (Hb) and an underlying electrode. The direct electron transfer process between Hb and the underlying electrode was realized without any electron mediator. Compared to that of a gold nanoparticle (AuNP)–Hb composite electrode, the catalytic current of a PEDOT nanowhiskers–AuNPs–Hb composite electrode for detecting H₂O₂ is increased 7 fold. A novel model of a H₂O₂ biosensor based on the PEDOT nanowhiskers–AuNPs–Hb composites was fabricated. The detection limit was estimated to be 0.6 μM at a signal/noise (S/N) ratio of 3, and the linear range of H₂O₂ concentration was from 1 μM to 1100 μM. Three constructed models of the biosensors showed a good stability, and all of them retained nearly 90% of their initial signals for 1 mM H₂O₂ when they were stored at 4 °C after 60 days. H₂O₂ concentration in contact lens nursing liquid was measured by the biosensor, and the results were in good agreement with the values provided by the supplier. It is shown that the PEDOT nanowhiskers can provide a new opportunity for the design of sensitive biosensors with long-term stability.