Redox-Active Glyconanoparticles as Electron Shuttles for Mediated Electron Transfer with Bilirubin Oxidase in Solution.

We demonstrate self-assembly, characterization and bioelectrocatalysis of redox-active cyclodextrin-coated nanoparticles. The nanoparticles with host-guest functionality are easy to assemble and permit entrapment of hydrophobic redox molecules in aqueous solution. Bis-pyrene-ABTS encapsulated nanoparticles were investigated electrochemically and spectroscopically. Their use as electron shuttles is demonstrated via an intraelectron transfer chain between neighboring redox units of clustered particles (Dh,DLS = 195 nm) and the mono- and trinuclear Cu sites of bilirubin oxidases. Enhanced current densities for mediated O2 reduction are observed with the redox nanoparticle system compared to equivalent bioelectrode cells with dissolved mediator. Improved catalytic stability over 2 days was also observed with the redox nanoparticles, highlighting a stabilizing effect of the polymeric architecture. Bioinspired nanoparticles as mediators for bioelectrocatalysis promises to be valuable for future biofuel cells and biosensors.