In vivo real-time brain biomonitoring with gold-coated tungsten (W-Au) based microbiosensors

A NADH and glucose biosensor based on thionine cross-linked multiwalled carbon nanotubes (MWNTs) and Au nanoparticles (Au NPs) multilayer functionalized indium-doped tin oxide (ITO) electrode were presented in this paper. The effect of light irradiation on the enhancement of bioelectrocatalytic processes of the biocatalytic systems by the photovoltaic effect was investigated. This bioelectrode exhibited excellent catalytic activity of the oxidation towards dihydronicotinamide adenine dinucleotide (NADH). Most interesting, the performance of this NADH sensor could be tuned by the visible light. When the biosensor was performed in the dark, the anodic current increased linearly with NADH concentration over the range from 0.5 to 237 μM with detection limit 0.1 μM and sensitivity 17 nA μM−1. The sensitivity became 115 nA μM−1 with detection limit 0.05 μM with the light irradiation. Compared with the reaction in dark, the sensitivity increased around 7 folds while the detection limit decreased 2 folds. The glucose biosensor also exhibited the same behavior. The linear range was from 10 μM to 2.56 mM with the sensitivity of 7.8 μA mM−1 and detection limit 5.0 μM in the dark. After the light irradiation, the linear range was from 1 μM to 3.25 mM with the sensitivity of 18.5 μA mM−1 and detection limit 0.7 μM. It indicated a potential to provide an operational access to develop new kinds of photocontrolled dehydrogenase enzyme-based bioelectronics.