Detection of tumor marker miRNA21 based on phosphorescent resonance energy transfer of Mn–ZnS QDs

Abstract

Since miRNA21 is a marker of many human tumors, trace detection of miRNA21 contributes to early tumor diagnosis. However, conventional methods are limited by complex sample preprocessing, high costs, or the interference from background fluorescence in biological fluids. Thus, developing simple and cheap miRNA-21 detection methods from biological fluids is very urgent. Our highlights are that: the miRNA-21 detection system based on phosphorescent resonance energy transfer solves the limitations of conventional methods, avoids the interference from the background fluorescence and scattering in biological fluids, eliminates complex sample preprocessing, and is more feasible for miRNA-21 detection in biological fluids. The principle of detection is that: QDs/PDADMAC (QDs⁺) nanohybrids were prepared from Mn–ZnS RTP QDs and cationic poly(diallyldimethylammonium chloride). Then a miRNA-21 sequence nanoprobe was built via the interaction between the QDs⁺ and 6-carboxy-X-rhodamine-DNA (ROX-DNA). The PRET between the QDs⁺ and ROX-DNA could quench the phosphorescence of the QDs⁺. After the gradual addition of the miRNA21 sequence, owing to the double-stranded structures formed between miRNA21 and ROX-DNA, the ROX-DNA desorbed from the surfaces of the QDs⁺, which gradually restored the phosphorescence of the QDs⁺. This nanoprobe had a detection limit of 1.60 nM and a detection range of 8–80 nM. This nanoprobe is more feasible for quantitative detection of miRNA21 in biological samples and has prospects in the medical diagnosis of tumors.