Simple in situ functionalizing of magnetite nanoparticles by 4-nitrobenzenediazonium for construction of a sensitive electrochemical DNA biosensor for detection of a DNA sequence related to Hepatitis B virus

Abstract

An in situ method for direct attachment of 4-nitrobenzenediazonium onto the surface of magnetite nanoparticles to develop an efficient template for construction of DNA electrochemical biosensor was proposed. For functionalization of magnetic nanoparticles, firstly azo salt of nitroaniline (4-nitrobenzenediazonium) was prepared and was reacted directly with magnetite nanoparticles in basic solution followed by electrochemical reduction of the terminal nitro group to amine. This NH2 group can interact with an activated phosphate group of non-labeled ss DNA related to Hepatitis B virus. Activated non-labeled ss DNA was prepared using N-(3 dimethylaminopropyl)-N-ethyl-carbodiimide hydrochloride and N-hydroxy-succinimide. The DNA hybridization events were monitored by differential pulse voltammetry measurement of the intercalated methylene blue as a well-known electrochemical indicator. Under optimal conditions, the reduction peak currents were linearly decreased with the increasing concentration of HBV target DNA from 7.8 (±0.2) × 10−13 mol L−1 to 8.8 (±0.3) × 10−9 mol L−1 with a detection limit of 3.3 (±0.2) × 10−13 mol L−1. This DNA biosensor exhibited excellent selectivity, reproducibility, and stability in the HBV DNA hybridization assay.