Surface Plasmon Resonance (SPR) and cyclic voltammetry based immunosensor for determination of teliosporic antigen and diagnosis of Karnal Bunt of wheat using anti-teliosporic antibody

In the present study attempts were made to develop an easy-to-use electrochemical immunosensor based on a modified gold disc for the detection of Karnal Bunt caused by quarantined fungus Tilletia indica. Teliosporeʹs from KB infected wheat grains were taken for preparation of four types of immunogen (intact, pellet, supernatant and sonicated) for raising anti-teliosporic polyclonal antibodies. The sensitivity of each immunosensor constructed with the different amounts of antigen solution, is determined by sensogram analysis and detection limit of the device is found to as low as 0.625 ng/μL using intact and pellet type antibodies against teliosporic antigen whereas on using supernatant and sonicated type antibodies it is 1.25 and 10 ng/μL. The cross-reactivity of pellet type of anti-teliospore antibodies with related fungal spores/teliospores was explained due to its polyclonal nature and also due to antigenic homology amongst pathogens. The functionalization of the immunosensor was characterized using electrochemical technique: cyclic voltammetry (CV). It was observed that oxidation current gradually decreases with modification viz. SAM + Au (661 μA), Ab + SAM + Au (402 μA), Ag + Ab + SAM + Au (297 μA) as compared to blank Au (gold) chip (918 μA). In future, this approach would be used in development of a portable immunosensor based on light emitted diode.