Detection of specific DNA sequences in Maize (Zea mays L.) based on phosphorescent quantum-dot exciton energy transfer

Abstract

The complementary sequence of genetically-modified marker sequence cauliflower mosaic virus 35S promoter (Ca MV 35S) DNA was trimmed and designed into sequences S1 and S2, which were separately modified onto the surfaces of room-temperature phosphorescent (RTP) quantum dots (QDs), forming QDs-S1 (P1) and QDs-S2 (P2), respectively. P1 and P2 were used as phosphorescent responsive units and identifying units. The target DNA sequence was added to induce P1 and P2 assembly aggregation, and the phosphorescence was self-quenched. Also, with the reduction of phosphorescence lifetime, a novel phosphorescent exciton energy transfer nano-probe system was built, which was used to quantitatively detect the genetically modified marker sequence Ca MV 35S in Maize (Zea mays L.). This simple and marker-free biological sensing method had a linear range of 10–200 nM for detecting the target DNA sequence (R = 0.991) and a detection limit (3σ) of 0.48 nM. Owing to the phosphorescence properties of QDs, this method is not affected by the background fluorescence and scattering light in biological fluids, and it is very feasible for the recognition and detection of genetically-modified marker sequences in biological samples.