Molecular interactions and structure of a supramolecular arrangement of glucose oxidase and palladium nanoparticles

This paper presents studies about the molecular interactions and redox processes involved in the formation of palladium nanoparticles associated to glucose oxidase (GOx-PdNPs) in a supramolecular arrangement. The synthesis occurs in two steps, the Pd reduction and the formation of the 80 nm sized supramolecular aggregates containing multiples units of GOx associated to 3.5 nm sized PdNPs. During synthesis, GOx molecules interact with Pd salt leading to metal ion and FAD reduction probably via the thiol group of the cysteine 521 residue. For the growing of PdNPs, formic acid was necessary as a co-adjuvant reducing agent. Besides the contribution for the redox processes, GOx is also necessary for the NP stability preventing the formation of precipitates resulted from uncontrolled growing of NPs Cyclic voltammetry of the GOx-PdNPs demonstrated electroactivity of the bionanocomposite immobilized on ITO (indium-tin oxide) electrode surface and also the NP is partially blocked due to strong interaction GOx and the surface of PdNPs. Vibrational spectroscopy (FTIR) showed that significant structural changes occurred in GOx after the association to PdNP. These mechanistics and structural studies can contribute for modulation of bionanocomposites properties.