Application Of Fluorescence Reasonance Energy Transfer (FRET) In DNA Detection

Sequence-specific DNA detection has been a topic of significant interest because of its application in the diagnosis of pathogenic and genetic diseases [1-2]. Recently, a variety of optical methods using nanoparticles have been developed for DNA sensing strategies, such as colorimetric detection, fluorescence resonance energy transfer (FRET), surface plasman resonance analysis. Compared with conventional chemical analysis, FRET-based analytical method has higher sensitivity and simplicity. In this paper, a novel FRET-based nanoprobe was presented.The paper showed that a FRET composed of 16 run gold nanoparticle linked to DNA molecules and 2.3 run MPA-capped CdTe Quantum Dots bound to DNA strands. We confirmed the overlap between emission spectrum of the QD as energy donor and the absorption spectrum of gold nanoparticles as energy acceptor. More than 95% spectra overlap between CdTe QDs and AuNPs promotes fluorescence resonance energy transfer (FRET).The nanoprobe was characterized by fluorescence spectrum. The results showed that the fluorescence intensity of nanoprobe is minimum. With the addition of target DNA,the distance between CdTe QDs and AuNPs becomes larger and the recovery of fluorescence was observed. The affect factors of nanoprobe system such as nucleotide overhang, the ratio of CdTe to AuNPs, pH value, retaining time were researched. The optimum conditions of the nanoprobe was obtained as follows: 6-nucleotide overhang, the ratio of CdTe to AuNPs is 1:5, pH=7.0, retaining time less than 12h. Through analysis of the data obtained, the quenching efficiency reached 74.55% , FRET radius is 4.07nm and the distance between CdTe and AuNPs is 3.41nm. At last, according to the difference of fluorescence recovery, the nanoprobe was used to detect the single-base mutant DNA.