Electrogenerated chemiluminescence energy transfer for the label-free detection of DNA

Photobleaching or DNA damage from more positive oxidation potential existed in DNA sensors using intercalators as fluorescent or electrogenerated chemiluminescent (ECL) probes. Herein, to solve the above problems, a new ECL energy transfer system was developed. Crystal violet (CV) intercalated into double strand DNA (dsDNA) was used as the energy receptor with excited luminol as the energy donor. ECL reaction of luminol was triggered by step pulse signal and excited luminol molecules transferred their energy to CV molecules. Excited CV molecules while returning to ground state will release energy, thereby emitting photons. The hybridization event was recognized by the different ECL energy transfer efficiencies due to different interaction abilities of single-stranded DNA (ssDNA) and dsDNA with CV. Thus, the ECL signal of CV-ssDNA was different from that of CV-dsDNA. Accordingly, the target DNA sequence could be identified and the target DNA concentration could be detected. The prominent advantage of this developed ECL energy transfer method was that the photobleaching effect in fluorescence and the high potential damage to DNA in electrochemical and ECL methods were avoided. Furthermore, probe DNA did not need to be labeled, which made the measurement of DNA simple, cheap and quick.