An ITO-based point-of-care colorimetric immunosensor for ochratoxin A detection.

The accurate and rapid ochratoxin A (OTA) detection at early stage can prevent people from getting cancer to a great extent due to its strong liver toxicity and renal toxicity. The development of an efficient strategy to detect OTA without sophisticated instruments is highly desired, but still remains a severe challenge. In this communication, a sandwich type point-of-care testing (POCT) immunoassay is developed for OTA detection. The 3-aminopropyltrimethoxysilane-glutaraldehyde (APTMS-GA) is used as color matrix and Au-N-TiO2 as labels for loading more captured antibodies and glucose oxidases (GOD). When glucose is added, GOD can be catalyzed to produce H2O2 which can weaken the color strength to quantify OTA concentrations. The mean gray values of reacted ITO-based immunosensors can be calculated by the software of Image J. The linear range of OTA is 0.0001-1 ng mL-1 with a low detection limit of 28 fg mL-1 at a signal-to-noise ratio of 3 s. This strategy can achieve the excellent performance without sophisticated instruments. This POCT method may has a potential application in the undeveloped countries with only a camera-equipped cellphone.