Carbon Dot-Modified Branched TiO2 Photoelectrochemical Glucose Sensors with Visible Light Response

The development of a photoelectrochemical (PEC) sensor for the sensitive and rapid detection of glucose is highly desirable. In PEC enzyme sensors, inhibition of the charge recombination of electrode materials is an efficient technique, and detection in visible light can prevent enzyme inactivation due to ultraviolet irradiation. In this study, a visible light-driven PEC enzyme biosensor was proposed, using CDs/branched TiO2 (B-TiO2) as the photoactive material and glucose oxidase (GOx) as the identification element. The CDs/B-TiO2 composites were produced via a facile hydrothermal method. Carbon dots (CDs) can not only act as photosensitizers but also inhibit photogenerated electron and hole recombination of B-TiO2. Under visible light, electrons in the carbon dots flowed to B-TiO2 and further to the counter electrode through the external circuit. In the presence of glucose and dissolved oxygen, H2O2 generated through the catalysis of GOx could consume electrons in B-TiO2, causing a decrease in photocurrent intensity. Ascorbic acid was added to ensure the stability of the CDs during the test. Based on the variation of the photocurrent response, the CDs/B-TiO2/GOx biosensor presented a good sensing performance of glucose in visible light, its detection range was from 0 to 9.00 mM, and the detection limit was 0.0430 mM.