Device Simplification: Example of the Application of a Bifunctional Molecularly Imprinted Polymer Membrane in a Visual Photoelectrochromic Chip

Considering that mycotoxin contamination, especially ochratoxin A (OTA), in food substrates poses a significant threat to human health, there is an urgent need for efficient on-site detection strategies to ensure food safety and facilitate a timely response. This study developed a novel and reusable visual point-of-care testing (POCT) device for on-site detection of OTA by integrating a photoelectrochromic sensing system with a microfabricated electrolytic cell fabricated via 3D printing. This streamlined, instrument-free configuration enhances portability and simplifies device fabrication. The signal generation region in this all-in-one chip was created through the electropolymerization of bifunctional molecularly imprinted polymers (MIPs) on the TiO₂/CdS substrate, while the signal output region employed a Prussian blue film that generated a unique colorimetric response readable by smartphone. The inclusion of bifunctional MIPs markedly improved the chip's photoresponse performance (up to 8.4-fold) and its selective recognition of OTA, achieving a broad linear response range from 0.5 to 120 ng/mL, with an impressive detection limit as low as 0.18 ng/mL. This integrated photoelectrochromic POCT platform offers rapid, intuitive, and stable detection, showing strong potential for next-generation in applications related to food safety monitoring and environmental analysis.