An ultrasensitive non-noble metal colorimetric assay using starch-iodide complexation for Ochratoxin A detection.

An ultrasensitive non-noble metal colorimetric assay using starch-iodide complexation for Ochratoxin A detection. Anal Chim Acta. 2020 Oct 23;1135:29-37 Authors: Suea-Ngam A, Deck LT, Howes PD, deMello AJ Abstract Colorimetric sandwich-type biosensors that can both provide sensitivity competitive with fluorescence-based approaches, and leverage reagents that are cost-effective, widely available and as safe as possible, are highly sought after. Herein, we demonstrate an alternative highly-sensitive colorimetric method for paper-based sandwich-type biosensing that uses starch-iodide complexation to simplify practical biosensing using ubiquitous reagents. Targeting the mycotoxin ochratoxin A (OTA), a covalently-immobilised OTA antibody on a cellulose surface captures OTA and forms a sandwich with OTA aptamer-conjugated glucose oxidase. Adding the chromogenic reagents at an optimized concentration, a distinct blue color develops within 30 min, offering excellent contrast with the clear/white of the negative sample. With a sampling volume down to just 5 μL, the assay exhibits concentration limits of detection and quantitation of 20 and 320 pg mL-1, respectively, and a linear range from 10-1 to 105 ng mL-1 (R2 = 0.997). The method displays excellent selectivity against related mycotoxins, excellent %recovery (95-117%) and robust operation in complex matrices (beer, urine and human serum), with no significant difference versus gol...
Source: Analytica Chimica Acta - Category: Chemistry Authors: Tags: Anal Chim Acta Source Type: research