Influence of macroporous gold support and its functionalization on lactate oxidase-based biosensors response.

A general bioanalytical platform for biosensor applications was developed based on three-dimensional ordered macroporous (3DOM) gold film modified electrodes using lactate oxidase (LOx) as a case study, within the framework of developing approaches of broad applicability. The electrode was electrochemically fabricated with an inverted opal template, making the surface area of the 3DOM gold electrode up to 18 times higher than that of bare flat gold electrodes. These new electrochemical transducers were characterized by using Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and the X-ray diffraction (XRD). The biosensor was developed by immobilization of lactate oxidase (LOx), on a 3DOM gold electrode modified with a self-assembled monolayer of dithiobis-N-succinimidyl propionate (DTSP). The resulting lactate oxidase biosensor was characterized by electrochemical impedance spectroscopy (EIS). The 3DOM gold electrode not only provides a good biocompatible microenvironment but also promotes the increase of conductivity and stability. Thus, the developed lactate oxidase bioanalytical platforms showed higher mediated bioelectrocatalytic activity compared to others previously described based on polycrystalline gold transducers. The response to varying lactate concentrations has been obtained in the presence of hydroxymethylferrocene as redox mediator in solution. Under these conditions, the bioanalytical platform response for DTSP covalently bound enzyme was improved with respect to that obtained in absence of DTSP.