Electrodes Based on PEDOT Nanotubes Decorated with Gold Nanoparticles for Biosensing and Energy Storage

Poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT-NTs) were electrochemically synthesized onto a stainless steel mesh electrode followed by one-pot electrodeposition of gold nanoparticles (AuNPs) at the nanotubular surface. The hybrid nanomaterial has shown remarkable electrochemical properties with the diminishment of the charge transfer resistance besides the possibility of further electrode modification by the thiol bonding at the AuNPs. The modified electrodes were deeply characterized by electrochemical techniques, in special by electrochemical impedance spectroscopy, which provides valuable information about the interfacial processes. The morphology of the nanomaterial was characterized by scanning electron microscopy and transmission electron microscopy images. The biosensing properties were evaluated through the avidin/biotin pair. The methodology of construction of the biosensor was further adapted to explore a cancer biomarker detection, the folate binding protein (FBP), which presented high sensitivity with a limit of detection of 4.5 pmol L–1, one of the lowest found in literature. Also, the hybrid material was used in the development of supercapacitors, the inclusion of AuNPs provided a remarkable durability of the PEDOT-NTs modified electrodes presenting long cycling stability (over 3000 cycles) and high energy density, compared with bare PEDOT nanotubes modified electrodes.