Label-Free Impedimetric Immunosensors for Detection of Snake Venoms Using Polyaniline as a Transducer Substrate

Abstract

Two label-free impedimetric immunosensors were developed to be employed in the specific diagnosis of snakebite. To produce the devices, a conductive substrate was obtained by electrodeposition of Polyaniline on the surface of a Crofer 22 APU steel. The polymer-based substrates were functionalized either with an affinity purified antibody specific for venom of the Bothrops genus or for the Crotalus genus. The performance of the as-prepared sensors was evaluated by exposing them to different concentrations of the venoms from Bothrops, Crotalus and Micrurus snakes. The capacity to recognize the specific analytes was measure by Electrochemical Impedance Spectroscopy within a frequency range from 10,000 Hz to 0.01 Hz. The increase of the immunosensors' charge transfer resistance was correlated to the increase in the concentration of the homologous venoms pool with a detection limit of 0.1 µg. m L-1. Heterologous venoms were not detected at any tested concentration, proving the expected high selectivity. Furthermore, the results showed the reusability of the sensor, as it retained the capability of detecting the specific analytes after many regeneration cycles. The use of immunosensors to detect snake venom shows important promise as an aid to snakebite treatment.