Rapid and sensitive electrochemical detection of DNA with Silver nanoparticle dispersed poly (9, 9-dioctylfluorene-ran-phenylene) nanocomposites

Abstract

In this study a sensitive electrochemical sensor for the detection of <em>E.coli</em> has been developed using silver nanoparticle (Ag) embedded poly(9,9-dioctylfluorene-ran-phenylene) (CFP) nanocomposite as a conductive platform and DNA hybridization technique. The new polymer was synthesized from 9,9-dioctylfluorene and 1,3-dichlorobenzene and biphenyl through Friedel Crafts alkylation reaction and the synthesized polymer as well as the Ag nanoparticles loaded composite were characterized using Fourier-transform infrared spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis. For accurate and rapid label-free electrochemical detection of pathogenic bacteria such as <em>E.coli</em>was studied by spin coating the nanocomposite suspension into indium tin oxide electrode (ITO) followed by the immobilization of aminoterminated oligonucleotide (pDNA), as probe. The resultant pDNA/Ag-CFP/ITO biosensor was then used to detect ssDNA, cleaved from genomic DNA of <em>E.coli</em>, using differential pulse voltammetry (DPV) technique. Under optimal experimental conditions, the biosensor could detect ssDNA in a wide linear range from 1 × 10-15 M to 1 × 10-22 M with a lowest detection limit of 1 × 10-22 M.