Development of a three-dimensional graphene-based photoelectrochemical biosensor and its use for monitoring lipase activity

In recent years, photoelectrochemical (PEC) biosensors have shown great application prospects in biological analysis and food detection. In this work, we developed and tested a new PEC biosensor. Three-dimensional graphene oxide (3DGO) was generated and deposited on an indium tin oxides (ITO) electrode. The photoelec-trically active poly[Nile blue] (PNb) was formed on this electrode by electropolymerization, and glycerol de-hydrogenase (GDH) was immobilised to generate the GDH-PNb-3DGO-ITO biosensor. This newly developed PEC biosensor exhibited excellent photoelectric response to lipase activity under light conditions, with a detection range of 0.1-6 U/mL and a lower detection limit of 0.069 U/mL. When the GDH-PNb-3DGO-ITO sensor was used for PEC detection of lipase activity by the standard addition recovery method, the recovery rate of the standard addition was 98.68-105.41%, and the relative standard deviation (RSD) was 2.1-3.5%, with good storage sta-bility and repeatability. Therefore, this work provides new ideas for the design and preparation of PEC biosensors and introduces a new detection method for monitoring lipase activity.