Dual amplified, sensitive electrochemical detection of pathogenic sequences based on biobarcode labels and functional graphene modified electrode

A dual signal amplified strategy for sensitive EC detection of pathogenic DNA sequences based on poly[G]20-conjugated biobarcode nanoparticles and carboxyl functionalized graphene is described. The capture probes are covalently linked to the graphene modified electrode. The addition of the target sequences and the biobarcode amplification labels leads to the formation of sandwich structures on the electrode surface. The presence of Ru(bpy)32+ in the detection buffer catalyzes the electro-oxidation of the numerous guanine bases captured on the electrode surface and generates significantly amplified current response for quantitation. Moreover, graphene can offer excellent heterogeneous electron transfer during electro-catalytic oxidation of guanine bases. This dual signal amplification strategy thus results in the determination of pathogenic DNA sequences down to the low picomolar level (1 pM). Our approach also exhibits excellent discrimination between the target and single-base mismatch sequences, which provides great potential for highly sensitive and selective detection of different nucleic acid sequences in general.