Coupling a target-triggered hybridization chain reaction to a glucose/oxygen biofuel cell for sensitive self-powered detection of ochratoxin A

Given the high toxicity of ochratoxin A (OTA) and its consequent threat to human health, the development of a portable OTA detection device is of great significance. Enzymatic biofuel cells (EBFCs) have been extensively demonstrated as portable self-powered devices without any external power supply, but self-powered detection of OTA by EBFCs has not been reported. Herein, we report a sensitive self-powered OTA sensor by integrating a target-triggered hybridization chain reaction (HCR) with a glucose/oxygen biofuel cell. OTA binding to a hairpin-locked aptamer opens the hairpin structure, exposing an HCR initiator strand. This initiator triggers HCR amplification, generating long double-stranded DNA products with numerous side strands. Subsequent strand displacement between these HCR side strands and glucose oxidase (GOD)-tagged double-stranded DNA releases GOD-tagged single-stranded DNA probes. These DNA probes hybridize with complementary DNA strands immobilized on the electrode surface, facilitating efficient immobilization of GOD molecules on the anode. With increasing OTA concentration, the GOD loading at the bioanode increases, enabling sensitive self-powered OTA detection. The self-powered sensor achieves a linear detection range from 1 pg mL^-1 to 5 ng mL^-1 and a detection limit of 0.7 pg mL^-1. This study provides a promising portable platform for OTA detection.