RESUMO
Self-powered electrochemical sensors based on photofuel cells have attracted considerable research interest because their unique advantage of not requiring an external electric source, but their application in portable and multiplexed targets assay is limited by the inherent mechanism. In this work, a portable self-powered sensor constructed with multichannel photofuel cells was developed for the ratiometric detection of mycotoxins, namely ochratoxin A (OTA) and patulin (PAT). The spatially resolved CdS/Bi2S3-modified photoanodes and a shared Prussian Blue cathode were integrated on an etched indium-tin oxide slide to fabricate the multichannel photofuel cell. The aptamers of OTA and PAT were covalently bonded to individual photoanode regions to build sensitive interfaces, and the specific recognition of analytes impaired the output performance of constructed PFC. Accordingly, ratiometric sensing of OTA and PAT was achieved by utilizing the output performance of a control PFC as a reference signal. This approach effectively eliminates the impact of light intensity on the accuracy of the detection. Under the optimal conditions, the proposed sensing chip exhibited linear ranges of 2.0-1000 nM and 5.0-500 nM for OTA and PAT, respectively. The detection limits (3 S/N) were determined to be 0.25 nM for OTA and 0.27 nM for PAT. The developed ratiometric sensing method demonstrated good selectivity and stability in the simultaneous detection of OTA and PAT. It was successfully utilized for the analysis of OTA and PAT real samples. This work provides a new perspective for construction of portable and ratiometric self-powered sensing platform.
