A photoelectrochemical sensor with reversible photocurrent polarity induced by hollow polyhedral flower-like CuO for sensitive detection of pro-gastrin releasing peptide.

Modulating the unidirectional increment or decrement of optical signals can effectively enhance the sensitivity of photoelectrochemical (PEC) sensors. However, this approach still faces significant challenges in practical applications due to false-positive detection results. To address this, we propose a "photocurrent polarity reversal" strategy to construct a hollow polyhedral flower-like CuO-induced Z-scheme heterojunction PEC sensor for the accurate and sensitive detection of Pro-Gastrin Releasing Peptide (Pro-GRP). By precisely controlling the heating rate, hollow polyhedral flower-like CuO was successfully synthesized, with its unique cavity structure significantly enhancing multiple light refraction and scattering effects, thereby improving light-harvesting efficiency. When CuO was introduced as a photocurrent polarity reversal component onto the In2O3/ZnCdS electrode surface, it altered the migration pathway of photogenerated carriers due to the energy band structure difference between CuO and In2O3/ZnCdS. This results in a reversal of the photocurrent polarity from anodic to cathodic photocurrent response, thereby enabling detection of Pro-GRP with enhanced specificity. This "photocurrent polarity reversal" strategy effectively eliminates potential false-positive signal interference, significantly improving detection accuracy and sensitivity. The sensor demonstrates excellent stability, anti-interference capability, and reproducibility, achieving a broad linear detection range of 10 fg/mL to 100 ng/mL with a detection limit of 3.62 fg/mL. Successful application in human serum Pro-GRP detection highlights its potential for early disease diagnosis and screening, offering new perspectives for sensitive biomarker detection.