PhotoelectrochemicalBiosensor Based on TiO₂/P5FIn with a Cascade AmplificationStrategy for Simultaneous Detectionof GSH and E2 Analytes of Ovarian Cancer

In this work, a photoelectrochemical (PEC) sensor for ovarian cancer detection was constructed based on TiO₂/poly(5-formylindole) (P5FIn)heterojunction using cascade amplification. The combined detection of multiple markers instead of a single detection mode can improve diagnostic accuracy. The photoelectron conversion efficiency and photocurrent response were significantly improved by the reaction of the detector glutathione (GSH) with cystine. 17β-Estradiol (E2) had a negative effect on the PEC response, reducing the photocurrent signal, and ultimately realizing the sensitive detection of GSH and E2. The PEC sensor had good detection performance for GSH and E2, with a linear detection range (LDR) of 0.5–1000 μM, and the limits of detection (LOD) were 0.167 μM and 0.1224 pM, respectively, with a detection range of 0.0003671–36.71 nM. Meanwhile, the PEC sensor also has good analytical capability, and this cascade signal amplification strategy has a potential development prospect in disease detection.