A photoelectrochemical glucose and lactose biosensor consisting of gold nanoparticles, MnO2 and g-C3N4 decorated TiO2

In this study, an innovative light-sensitive hybrid material was used for the photoelectrochemical (PEC) biosensor fabrication. Herein, gold nanoparticles modified mesoporous TiO2 was coated on an indium fin oxide substrate, after a layer of MnO2/g-C3N4 was introduced to develop a PEC biosensor that yielded a favorable electronic interface for photo-excited electron injection. Glucose oxidase and beta-galactosidase were co-immobilized on the photoanode surface via silane/glutaraldehyde linkage chemistry for glucose and lactose determination. Au NPs, g-C3N4, and MnO2 were utilized to modify quintessential semiconductor TiO2 owing to their narrow band gaps, appropriate position of the valence and conduction bands, and high visible light absorption. The p-n heterojunction formation at the interface of MnO2 and g-C3N4/TiO2 was presumed, and the heterojunction facilitates the charge transport and inhibit the recombination of excited electrons. Direct electron transfer led to the hole scavenging by FADH(2), which reinforced the photocurrent. The linear measurement ranges were calculated in the range of 0.004-1.75 mM, with a sensitivity of 1.54 mu AmM-1 cm(-2) for glucose at 0 V, and 0.008-2.50 mM, with a sensitivity of 1.66 mu AmM-1 cm(-2) for lactose at -0.4 V. To the best of our knowledge, we report the first PEC lactose biosensor, and this study opens the door to PEC multianalyte detection.