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

• First demonstration of nano-yeast–scFv based immunosensor on a portable-low cost platform.
• New antibody/antigen combination demonstrates that nano-yeast–scFv can be routinely engineered towards diverse target antigens.
• Nano-yeast–scFv based immunosensor was successfully used for E. histolytica antigen detection in a biological matrix derived from human stool.

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 electrochemical 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.

We report a low-cost affinity reagent, nano-yeast–scFv, on a commercially available, inexpensive, and portable screen-printed electrode for the label-free electrochemical detection of Entamoeba histolytica cyst antigens in a biological matrix.Figure optionsDownload as PowerPoint slide