Highly Sensitivein vitroBiosensor for EnterotoxigenicEscherichia coliDetection Based on ssDNA Anchored on PtNPs‐Chitosan Nanocomposite

Abstract

AbstractDetection of EnterotoxigenicEscherichia coliin various biological samples has tremendous importance in human health. In this direction, we have designed a label free electrochemical biosensor for highly selective detection ofEscherichia colithrough detecting ST gene. The ability of sensor probe to detect STGwas confirmed using polymerase chain reaction. The biosensor was fabricated based on STGspecific probes immobilized on platinum nanoparticles chitosan nanocomposite on screen printed carbon electrode, which was characterized by cyclic voltammetry, transmission electron microscopy, and fourier transform infrared spectroscopy. A highly sensitive label free sensing was achieved by analyzing STGhybridization using electrochemical impedance spectroscopy (EIS) technique. The EIS analysis showed a significant increase in charge transfer resistance after STGinteraction with the highly selective ssDNA probe immobilized on the nanocomposite film. The increase in charge transfer resistance was evaluated for varying concentrations of STG, which shows a dynamic range between 1.0×10−12and 1.0×10−4with the detection limit of 3.6×10−14 M (RSD<4.5 %). The regeneration of sensor probe was also studied and interference due to non‐target sequences was evaluated to ensure the selectivity of the designed sensor. The practical applicability of sensor probe was also analyzed by detecting the STGfrom the bacteria present in surface water.