Real time PCR based on fluorescent quenching of mercaptoacetic acid-modified cdte quantum dots for ultrasensitive specific detection of nucleic acids

A ultra-sensitive, highly specific, real-time polymerase chain reaction system based on mercaptoacetic acid-modified CdTe nanocrystals(mQDs) is reported. With the addition of 3 nm mQDs into the PCR reagent, the photoluminescent(PL) intensities of mQDs decreased gradually as the DNA templates and PCR cycles increased, in an approximate negative linear relation to the DNA concentration logarithm or cycles, the PL peaks exhibited red-shifts synchronously. Mg²⁺ ions decreased the PL intensity of mQDs in a dose-dependent means, and Taq DNA polymerase enhanced the PL intensity of mQDs in a dose-dependent means. Real-time PCR based on mQDs showed an increased sensitivity at least 103 fold higher than that based on SYBR Green I. The specificity of PCR was enhanced in the PCR reagent with less than 1.33mg/mL mQDs. The potential mechanism is also discussed. This novel PCR system based on mQDs has great potential in applications such as ultra-sensitive specific DNA or RNA detection, dynamic molecular imaging, and photoelectric biosensors.