Electrogenerated chemiluminescence detection for deoxyribonucleic acid hybridization based on gold nanoparticles carrying multiple probes

A novel sensitive electrogenerated chemiluminescence (ECL) method for the detection deoxyribonucleic acid (DNA) hybridization based on gold nanoparticles carrying multiple probes was developed. Ruthenium bis(2,2′-bipyridine)(2,2′-bipyridine-4,4′-dicarboxylic acid)-N-hydroxysuccinimide ester (Ru(bpy)2(dcbpy)NHS) was used as a ECL label and gold nanoparticle as a carrier. Probe single strand DNA (ss-DNA) was self-assembled at the 3′-terminal with a thiol group to the surface of gold nanoparticle and covalently labeled at the 5′-terminal of a phosphate group with Ru(bpy)2(dcbpy)NHS and the resulting conjugate, (Ru(bpy)2(dcbpy)NHS)-ss-DNA-Au, was taken as a ECL probe. When target analyte ss-DNA was immobilized on a gold electrode by self-assembled monolayer technique and then hybridized with the ECL probe to form a double-stranded DNA (ds-DNA), a strong ECL response was electrochemically generated. The ECL intensity was linearly related to the concentration of the complementary sequence (target ss-DNA) in the range from 1.0 × 10−11 to 1.0 × 10−8 mol L−1, and the linear regression equation was S = 57301 + 4579.6 lg C (unit of C is mol L−1). A detection limit of 5.0 × 10−12 mol L−1 for target ss-DNA was achieved. The ECL signal generated from many reporters of ECL probe prepared is greatly amplified, compared to the convention scheme which is based on one reporter per hybridization event.