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

In this study a sensitive electrochemical sensor for the detection of E.coli 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 E.coliwas 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 E.coli, 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.