A hybrid biocatalyst consisting of silver nanoparticle and naphthalenethiol self-assembled monolayer prepared for anchoring glucose oxidase and its use for an enzymatic biofuel cell

Abstract

A novel hybrid biocatalyst is synthesized by the enzyme composite consisting of silver nanoparticle (AgNP), naphthalene-thiol based couplers (Naph-SH) and glucose oxidase (GOx), which is then bonded with the supporter consisting of polyethyleneimine (PEI) and carbon nanotube (CNT) (CNT/PEI/AgNPs/Naph-SH/GOx) to facilitate glucose oxidation reaction (GOR). Here, the AgNPs play a role in obstructing denaturation of the GOx molecules from the supporter because of Ag-thiol bond, while the PEIs have the AgNPs keep their states without getting ionized by hydrogen peroxide produced during anodic reaction. The Naph-SHs also prevent ionization of the AgNP by forming self-assembled monolayer on their surface. Such roles of each component enable the catalyst to form (i) hydrophobic interaction between the GOx molecules and supporter and (ii) π-conjugated electron pathway between the GOx molecules and AgNP, promoting electron transfer. Catalytic nature of the catalyst is characterized by measuring catalytic activity and performance of enzymatic biofuel cell (EBC) using the catalyst. Regarding the catalytic activity, the catalyst leads to high electron transfer rate constant (9.6±0.4s−1), low Michaelis-Menten constant (0.51±0.04mM), and low charge transfer resistance (7.3Ωcm2) and high amount of immobilized GOx (54.6%), while regarding the EBC performance, high maximum power density (1.46±0.07mWcm−2) with superior long-term stability result are observed.