Ultrasensitive electrochemiluminescence detection of lengthy DNA molecules based on dual signal amplification

Aimed at the facile detection of lengthy DNA molecules, an easily operated sandwich-type electrochemiluminescence (ECL) DNA biosensor was constructed on a glassy carbon electrode (GCE) based on CdTe quantum dots coated hollow ZnO nanoparticles (CdTe-ZnO NPs)-S2O82- ECL system in this work. To fabricate a high-performance protocol, the GCE surface was successively modified by graphene nanosheet (GS), carbon nanotube (CNT) and gold nanoparticles (AuNPs) to form AuNPs dotted CNT-GS composites (Au@CNT-GS) platform, which improved the electronic transmission rate as well as increased the amount of immobilized capture probe CMV-F (S-1). For further ultrasensitive, stable and low-potential ECL detection, CdTe-ZnO NPs were synthesized, and employed to label signal probe T7 promoter (S-3). Based on the hybridization effect, the immobilized capture probe S-1, target DNA and labeled signal probe S3 formed a sandwich-type DNA complex, which produced the ECL emission in the presence with S2O82- coreactant. Under optimal conditions, the DNA ECL biosensor showed a good linear range over 10(-14) M to 10(-19) M with a low detection limit of 0.61 x 10(-19) M. The proposed strategy demonstrates a reproducible, stable, and potent method that can be expanded to detect the genome which exists in living cells.