Detection of ochratoxin A in wine and beer by chemiluminescence-based ELISA in microfluidics with integrated photodiodes

Ochratoxin A (OTA) is a mycotoxin produced by naturally occurring fungi in crops such as grapes and cereals. OTA has demonstrated toxicity and carcinogenicity in animals and therefore biosensing systems are required for its detection and quantification in commercialized goods. This work demonstrates an integrated analytical system that conjugates an indirect competitive enzyme-linked immunosorbent assay strategy developed in PDMS microfluidics with integrated microfabricated hydrogenated amorphous silicon photodiodes for chemiluminescence detection. A limit of detection of 0.85 ng/mL was obtained for OTA detection in a PBS solution using a straight-channel configuration. Comparable limits of detection were obtained for beer extracts but for red wine extracts a higher limit of detection of OTA of 28 ng/mL was obtained. A two-channel U-shaped microfluidic device was developed to perform the simultaneous analysis of a reference solution and of an ochratoxin A contaminated solution. This configuration efficiently reduced measurement errors resulting in an improvement of one order of magnitude in the limits of detection of OTA in beer and red wine extracts. The results show that the miniaturized system can be developed into one stage of a future highly sensitive, portable, and fully integrated "toxin-chip" for monitoring food safety applications. (C) 2012 Elsevier B.V. All rights reserved.