An impedimetric DNA sensor based on functionalized magnetic nanoparticles for HIV and HBV detection

We report a new approach based on DNA hybridization for detecting HBV virus using non-faradic electro-chemical impedance spectroscopy. DNA probes modified with biotin in 5' position were immobilized on streptavidin modified magnetic nanoparticles by biotin-streptavidin interaction. A layer of functionalized nanoparticles was directly immobilized on bare gold electrode using a magnet. Before detection atomic force microscopy was used to visualize the layer of magnetic nanoparticles and cyclic voltammetry permitted to characterize DNA probe immobilization. The hybridization reactions with specific complementary DNA target and no complementary target were investigated by non-faradic impedance spectroscopy. Results show the good immobilization of the DNA probes and the hybridization with different concentrations of complementary DNA. Non-faradic impedance spectroscopy allows to detect 50 pmol of HBV DNA and 160 pmol of HIV DNA on sample of 20 mu L Saturations were reached for the same concentration 12.65 nmol/mL for a same quantity of immobilized DNA probes. (C) 2008 Elsevier B.V. All rights reserved.