Electrochemiluminescence Resonance Energy Transfer Between CdS:Eu Nancrystals and Au Nanorods for Sensitive DNA Detection

This work provides a novel electrochemiluminescence resonance energy transfer (ECL-RET) system using CdS:Eu nanoscrytals (NCs) as an ECL donor and Au nanorods (Au NRs) as an ECL acceptor. CdS:Eu NC, prepared by doping 1.596 Eu3+ ions into CdS NCs, exhibits strong and stable cathodic ECL emissions in the presence of coreactant S2O82- ions with two ECL spectral bands at 450-550 nm from the host CdS and at 600-700 nm due to the energy transfer from host CdS to Eu3+ ions. Au nanorods (Au NRs) have two absorption peaks that are easily tuned to match well with the ECL emission spectrum of the CdS:Eu NCs film by adjusting the aspect ratio of the nanorods to get a highly effective ECL-RET. Here, we studied the spectrum, distance and shape dependence of the efficiency of ECL-RET between the NCs' ECL and different Au nanoparticles (Au NPs) on the basis of the stem-loop structure DNA with a 6-base-pair (bp) stem ancra 12, 30, or 45 nucleotide (nct) loop. At the optimized conditions, the system could be used to ultrasensitivly and specifically detect target DNA, providing significant potential application in clinical analysis.