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An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH_2 labeled,single strand DNA(NH_2-ssDNA) onto a self-assembled diazo-thiourea and gold nanoparticles modified Au electrode(diazo-thiourea/GNM/Au).Gold nano-particles expand the electrode surface area and increase the amount of immobilized thiourea and single stranded DNA(ssDNA) onto the electrode surface.Diazo-thiourea film provides a surface with high conductibility for electron transfer and a bed for the covalent coupling of NH_2-ssDNA onto the electrode surface.The immobilization and hybridization of the probe DNA on the modified electrode is studied by differential pulse voltammetry(DPV) using methylene blue(MB) as a well-known electrochemical hybridization indicator.The linear range for the determination of complementary target ssDNA is from 9.5(±0.1) × 10~(-13) mol/L to1.2(±0.2) x 10~(-9) mol/L with a detection limit of 1.2(±0.1) > 10~(-13) mol/L.
An effective procedure for constructing a DNA biosensor is developed based on covalent immobilization of NH_2 labeled, single strand DNA (NH_2-ssDNA) onto a self-assembled diazo-thiourea and gold nanoparticles modified Au electrode (diazo-thiourea / GNM / Au). Gold nano-particles expand the electrode surface area and increase the amount of immobilized thiourea and single stranded DNA (ssDNA) onto the electrode surface. Diazo-thiourea film provides a surface with high conductibility for electron transfer and a bed for the covalent coupling of NH_2 -ssDNA onto the electrode surface. immobilization and hybridization of the probe DNA on the modified electrode is studied by differential pulse voltammetry (DPV) using methylene blue (MB) as well well known electrochemical hybridization indicator. The linear range for the determination of complementary target ssDNA is from 9.5 (± 0.1) × 10 ~ (-13) mol / L to 1.2 (± 0.2) × 10 ~ (-9) mol / L with a detection limit of 1.2 (-13) mol / L.