An amperometric biosensor and a biofuel cell of uric acid based on a chitosan/uricase-poly(furan-3-boronic acid)-Pd nanoparticles/plated Pd/multiwalled carbon nanotubes/Au electrode

A chitosan (CS)/uricase (UOx)-poly(furan-3-boronic acid) (PFBA)-Pd nanoparticles (PdNPs)/plated Pd (Pd-wate)/multiwalled carbon nanotubes (MWCNTs)/Au electrode was prepared for fabricating an amperometric biosensor and a biofuel cell (BFC) of uric acid (UA). Briefly, Pd was electroplated on a MWCNTs-modified Au electrode, the UOx-PFBA-PdNPs bionanocomposite was prepared on the Pd-plate/MWCNTs/ Au electrode through chemical oxidation of a UOx-furan-3-boronic acid adduct by Na2PdCl4, and then chitosan (CS) was cast-coated on the electrode. In the first-generation biosensing mode (anodic detection of enzymatically generated H2O2), the prepared CS/UOx-PFBA-PdNPs/Pd-plate/MWCNTs/Au electrode showed a linear amperometric response to UA concentration from 1.0 mu M to 2.5 mM with a sensitivity of 490 mu A mM(-1) cm(-2) and a limit of detection (S/N = 3) of 0.1 mu M, excellent operation/storage stability, and good results of UA assay in real urine samples. The enzyme electrode also worked well in the second-generation biosensing mode involving a p-benzoquinone or ferrocene monocarboxylic acid mediator. Furthermore, a monopolar UA BFC was fabricated by using the enzyme electrode as the bioanode and a Pt/MWCNTs/Au electrode as the cathode, which gave an open-circuit cell voltage of 0.394 V, a short-circuit current density of 857 mu A cm(-2) and a maximum power density of 70 mu M cm(-2) at 0.22 V under simulated physiological conditions. (C) 2014 Elsevier B.V. All rights reserved.