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 1.5% Eu 3+ ions into CdS NCs, exhibits strong and stable cathodic ECL emissions in the presence of coreactant S 2 O 82- 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 Eu 3+ 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 and a 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. © 2012 American Chemical Society.