Single-domain antibody based thermally stable electrochemical immunosensor.

Conventional monoclonal and polyclonal antibodies are sensitive to changes in environmental factors such as temperature, pH, humidity, etc. This limits the current cost-effective and portable electrochemical immunosensors in harsh environments. Using Ricin Chain-A, a naturally occurring toxin, as a model analyte we report fabrication of a thermally stable electrochemical immunosensor. Single-domain antibodies (sdAb) or nanobodies have been employed as recognition elements for direct detection of Ricin at temperatures great than 4°C. Immunosensor fabricated using the conventional Ricin monoclonal and polyclonal antibodies have also been demonstrated for comparison. In the case of sdAb immunosensor, Ricin was detected in a linear range of 1log(fg/mL)-1log(μg/mL) with a sensitivity of 0.07μA/log(g/mL)/cm(2) using cyclic voltammetry. The fabricated miniaturized sensors have demonstrated higher shelf life and stability at temperatures up to 40°C. Therefore these electrochemical sensors can be integrated as a part of a portable device for point-of-care immunosensing.