A highly sensitivity electrochemistry biosensor for E. coli DNA detection based on hollow and porous dCuO@rGO composite

Abstract

A highly sensitive DNA (deoxyribonucleic acid) sensor was prepared by using dCuO particles (derived from HKUST-1), electrochemical-reduced graphene oxide (rGO) and chitosan (CS) composite modified glassy carbon electrode (CS/dCuO@rGO/GCE). The morphology and nanostructure features of dCuO have been characterized with the HRTEM and SEM techniques. Electrochemical impedance spectroscopy characterisation (EIS) test showed that dCuO@rGO composite with a straight line which displaying the faster electron transfer rate compared to the Rct value obtained on dCuO (267 Ω) and rGO (47 Ω), this high conductivity was according with cyclic voltammetry (CV) results. It was ascribed to the octahedral hollow, porosity dCuO accelerated the electrolyte permeation capacity, and rGO with large surface area enhancing the electro-active site. Besides, the electro-reduction formed hybrid material of dCuO@rGO with well-synergetic effect significantly promoted the conductivity property. Of noteworthy, FT-IR spectroscopy indicating the retained carboxyl groups of dCuO, which could serve as functional arm-linker for capturing 5′-NH2 modified probe DNA (S1) to build the bio-sensing electrode (S1-CS/dCuO@rGO/GCE). Differential pulse voltammetry (DPV) characterization showed this manufactured biosensor with super-highly sensitivity for colitoxin DNA detection. The specific ssDNA sequences were detected in the concentration range from 0.001 to 37.5 pM with lower detection limit value of 3.89 × 10−1 fM (S/N = 3). This biosensor also showed well discrimination ability to the non-complementary and mismatched DNA sequences.