Photoelectrochemical nanosensors: An emerging technique for tumor liquid biopsy

As a noninvasive substitute for traditional tissue biopsy, liquid biopsy has emerged as a novel method for the early diagnosis of malignant tumors. In the past decade, low-cost biosensors have been widely studied, and compared to other methods, they have exhibited superior performance in bioanalysis, including liquid biopsies. With the advanced generation of optical and electrochemical biosensors, photoelectrochemical (PEC) biosensors coupled with nanosciences (referred to as PEC nanosensors) have attracted much attention in recent years as they have reached an even higher sensitivity. In this review, the working principle, detection strategy and photoactive nanomaterials of PEC nanosensors were summarized, recent applications of PEC nanosensors for diagnosing different tumor biomolecules in liquid samples were reviewed, and the design processes for each type of PEC nanosensors were especially considered. Finally, some perspectives on developing PEC nanosensors were provided. This review provides systematic retrospective analysis and insights for developing PEC nanosensors in cancer liquid biopsy.