Portable self-powered electrochemical aptasensing platform for ratiometric detection of mycotoxins based on multichannel photofuel cell

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.

The validated and sensitive HPLC-DAD method for determination of patulin in strawberries

This work outlines HPLC coupled with DAD detection for accurate quantification of patulin (mycotoxin) in strawberries. The optimized extraction of fruit samples through the modified QuEChERS technique in acetonitrile acidified with acetic acid (1%, v/v) and citrate-buffered salts followed by dispersive solid phase extraction using a primary secondary amine and graphitized carbon is described. The method presents LOD and LOQ of 1.5 and 5µg/kg, respectively and has been validated in strawberry matrix at three concentration levels (5, 10 and 50µg/kg), according to SANTE/11945/2015 and the 2002/657/EC Decision requirements. All validated patulin levels show high percentage of patulin recovery. The validation procedure also includes the intermediate precision performed within three successive days in samples spiked with patulin. The developed method was applied for analysis of fresh and frozen strawberries purchased at local markets. Patulin level in analyzed samples was below the level of detection.