Nano-yeast-scFv probes on screen-printed gold electrodes for detection of Entamoeba histolytica antigens in a biological matrix

The time and costs associated with monoclonal antibody production limit the potential for portable diagnostic devices to penetrate the market. Replacing the antibody with a low-cost alternate affinity reagent would reduce the costs of diagnostic development and use, and lead to new portable diagnostic devices towards many diseases. Herein, we present low-cost affinity reagents, nano-yeast scFv, on commercially available, inexpensive, and portable screen-printed electrodes for the label-free electro-chemical detection of Entamoeba histolytica cyst antigens. The biosensor was able to detect antigen at concentrations down to 10 pg mL(-1) in buffer with an inter-assay reproducibility of (% RSD, n=3) 4.1%. The applicability of two differently engineered nano-yeast scFv to each specifically detect their cognant E. histolytica cyst antigens was demonstrated in a biological matrix derived from human stool. Because of the simple, inexpensive, and sensitive nature of this methodology, it may offer a low-cost alternative to immunosensors based on antibody-target recognition. (C) 2013 Elsevier B.V. All rights reserved.