Recent advances in electron manipulation of nanomaterials for photoelectrochemical biosensors

Photoelectrochemical (PEC) biosensing as a promising and largely developing technique has been widely applied in biological analysis in recent years because of its low background signal and high sensitivity. By utilizing suitable PEC active materials to establish a photoelectric (PE) conversion system, selective and sensitive measurements can be achieved with the help of specific biological recognition elements. PEC biosensors rely on the change of photocurrent that depends on the electron transfer process of nanomaterials. Therefore, the electron manipulation of PEC active nanomaterials is crucial for PEC sensing. In this review, from the perspective of the electron transfer manipulation of PEC active nanomaterials, we summarize the principle of PEC biosensors in three parts, i.e., generation of excited electrons in PEC active materials, introduction of specific materials for the formation of new electron transfer pathways, and separation of excited electrons in semiconductors. For each part, typical PEC biosensors are displayed and compared to reveal the superiority of different principles. In addition, current challenges of PEC biosensors are discussed, and some insight is given into the development of PEC biosensors in the future.