A novel disposable electrochemical DNA biosensor for the rapid detection of Bacillus thuringiensis

A custom designed DNA probe against cry1 gene of Bacillus thuringiensis has been used to fabricate a DNA biosensor by self-assembled monolayers of mercaptohexanol (MCH) and thiol-linked custom designed probe (ssDNA-thiol), immobilized on a screen printed gold nanostructured electrode. DNA immobilization and hybridization have been characterized by differential pulse voltammetry (DPV) using methylene blue as an electrochemical hybridization indicator. With this approach, the target DNA could be quantified in the range of 1.0 x 10(-6) M to 1.0 x 10(-12) M, with a detection limit of 0.997 x 10(-12) M by 3 sigma. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) have been performed to characterize the sequentially modified electrode. In addition, a non-complementary DNA sequence of Bacillus cereus has been tested as a non-target, that hardly causes any variation in the reduction current of MB reaffirming that the DNA-based biosensor is high selective to Bacillus thuringiensis. The electrochemical detection methods employed in this work can be extended further to develop DNA-based biosensors for the detection of other microorganisms having applications in agriculture, food industries and medical applications.