Photoelectrochemical detection of hyaluronidase activity via enzyme-mediated release of hyaluronic acid-functionalized CdS quantum dots.

At the forefront of analytical detection technologies, photoelectrochemical (PEC) sensing platforms offer significant advantages due to their unique photo-electric synergistic mechanism, with excellent photoactive materials being fundamental for high sensitivity. In this study, we present a novel PEC composite, formed by covalently coupling polyethyleneimine (PEI)-functionalized CuInZnS nanoflowers (CIZS) and hyaluronic acid (HA)-functionalized CdS quantum dots (QDs). This innovative composite constructs a robust PEC bioanalytical platform for effective detection of hyaluronidase (HAase), a critical biomarker for cancers like prostate and bladder. Compared to individual components, the CdS QDs-modified CIZS nanoflowers show significantly enhanced anodic photocurrent under visible light, attributed to improved light absorption and more efficient charge separation. Leveraging HAase's specific enzymatic activity, we designed a strategy where HA within the composite is cleaved, releasing CdS QDs and causing a substantial anodic photocurrent decrease. This enables sensitive HAase detection in human urine. The anodic photocurrent linearly correlates with the logarithm of HAase activity (0.010-80 U/mL), achieving a low detection limit of 0.0041 U/mL. Our work introduces a new CIZS-based PEC detection methodology and an enzyme-regulated PEC bioanalytical strategy, offering a simple and efficient tool for bioanalytical applications.