Electrochemical determination of M. tuberculosis antigen based on Poly(3,4-ethylenedioxythiophene) and functionalized...

An electrochemical DNA aptasensor for the detection of Mycobacterium tuberculosis (M. tb) antigen MPT64, was developed using Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). The biotinylated aptamer was immobilized onto streptavidin attached to -COOH functionalized CNTs via streptavidin-biotin interaction. Various characterization studies as FT-IR, FE-SEM, EIS and DPV were done to validate each fabrication step of the aptasensor. Optimization studies related to aptamer concentration and response time were performed. The electrochemical signal generated from the aptamer-target molecule interaction was monitored electrochemically by differential pulse voltammetry in the presence of [Fe(CN)₆]^3-/4- as a redox probe. The aptasensor exhibited limit of detection of 0.5±0.2fgmL^-1 within 15min with stability of 27 days at 4°C and reusability of 7 times after repeated regeneration with 50mM NaOH. The potential application of the aptasensor was established by spike-in studies to obtain recovery in between (88-95)%.