Abstract: This study addresses the critical challenge of limited dissolved oxygen in traditional photoelectrochemical enzyme biosensors by proposing a construction strategy for a “solid-liquid-gas three-phase enzymatic reaction interface”, utilizing a three-dimensional (3D) dendritic nanostructure. The methodology involves the preparation of titanium dioxide (TiO2) nanowire arrays featuring a 3D dendritic structure on fluorine-doped tin oxide conductive glass through a two-step hydrothermal process. Following selective hydrophobic and hydrophilic treatments, along with enzyme modification, a stable three-phase interface was successfully established. This innovative design facilitates the direct transport of oxygen to the catalytic sites via the gas phase, effectively addressing the limitations associated with insufficient oxygen supply at the conventional solid-liquid two-phase interface. Experimental results demonstrate that the linear detection range of this sensor has been enhanced by a factor of 20 compared to traditional structures, while exhibiting excellent stability (relative standard deviation < 2%). This research introduces a novel construction strategy for the development of highly sensitive and stable photoelectrochemical sensors, which may significantly contribute to the early diagnosis of chronic diseases.

Key words: Photoelectrochemical biosensor, 3D branched TiO₂ nanoarrays, Three-phase interface, Oxidase