Fabrication of high-intensity electron transfer electrochemiluminescence interface for Hg 2+ detection by using reduced graphene oxide-Au nanoparticles nanocomposites and CdS quantum dots

Abstract A novel electrochemiluminescence (ECL) biosensing interface for Hg 2+ analysis was constructed based on the enhanced ECL signal from CdS quantum dots by reduced graphene oxide-Au nanoparticles (RGO-AuNPs) nanocomposites. RGO-AuNPs were prepared by the heat-treatment of graphene oxide and HAuCl 4 solution under alkaline environment. The prepared RGO-AuNPs composites were dispersed in N , N -dimethylformamide and dropped onto the surface of glassy carbon electrode (GCE). Double-stranded DNA modified with amino at one end was then immobilized on the RGO-AuNPs/GCE surface in the presence of 1-pyrenebutyric acid N -hydroxysuccinimide linker, following which the avidin-modified CdS quantum dots were linked to double-stranded DNA labeled with biotin at another end through the formation of biotin–avidin complex. The excellent electrical conductivity of RGO-AuNPs nanocomposites and the high charge transfer efficiencies of the double-stranded DNA with T–Hg 2+ –T complex, which produced high-intensity electron transfer interface and improved the sensitivity of the biosensor. After Hg 2+ was added into the detection solution, the increased ECL signals showed good correlation with Hg 2+ concentration. The linear range of the sensor was 5.0 × 10 −13 –1.0 × 10 −9  M with a detection limit of 2.0 × 10 −13  M. This ECL biosensor showed satisfactory results when used for detecting Hg 2+ in real lake water.