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

Abstract A chitosan (CS)/uricase (UOx)–poly(furan-3-boronic acid) (PFBA)–Pd nanoparticles (PdNPs)/plated Pd (Pd plate )/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 Na 2 PdCl 4 , and then chitosan (CS) was cast-coated on the electrode. In the first-generation biosensing mode (anodic detection of enzymatically generated H 2 O 2 ), the prepared CS/UOx–PFBA–PdNPs/Pd plate /MWCNTs/Au electrode showed a linear amperometric response to UA concentration from 1.0 μM to 2.5 mM with a sensitivity of 490 μA mM −1  cm −2 and a limit of detection ( S / N  = 3) of 0.1 μM, 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 μA cm − 2 and a maximum power density of 70 μW cm − 2 at 0.22 V under simulated physiological conditions.