Photoelectrochemical Enzyme Biosensor Based on TiO₂ Nanorod/TiO₂ Quantum Dot/Polydopamine/Glucose Oxidase Composites with Strong Visible-Light Response

Abstract

Although photoelectrochemical (PEC) enzyme biosensors based on visible-light detection would have a high practical value, their development has been limited by the weak visible-light response of available photoactive substrates. Here, to enhance the visible-light response of a photoelectric substrate, a TiO₂ nanorods (NRs)/TiO₂ quantum dots (QDs)/polydopamine (PDA)/glucose oxidase nanocomposite was prepared <i>via</i> hydrothermal synthesis, followed by photopolymerization. TiO₂ QDs with strong light absorption and excellent photocatalytic activity were introduced between the TiO₂ NRs and the PDA. An efficient electron transport interface that formed as a result of the combination of the TiO₂ NRs, TiO₂ QDs, and the PDA could not only transfer electrons quickly and orderly, but also substantially improve the response of the TiO₂ NRs under visible light. Through a series glucose detection, a sensor based on the nanocomposite was found to exhibit superior sensing performance under visible light with a sensitivity of 4.63 μA mM^-1 cm^-2, a linear response over the concentration 0.1-4 mM, and a detection limit of 8.16 μM. This work proposes a biosensor that can detect under visible light, thereby expanding the application range of PEC enzyme biosensors.