Determination of cDNA encoding BCR/ABL fusion gene in patients with chronic myelogenous leukemia using a novel FRET-based quantum dots-DNA nanosensor.

In the present study, we developed a sensitive method based on fluorescence resonance energy transfer (FRET) for the determination of the BCR/ABL fusion gene, which is used as a biomarker to confirm the clinical diagnosis of both chronic myelogenous leukemia (CML) and acute lymphocytic leukemia (ALL). For this purpose, CdTe quantum dots (QDs) were conjugated to amino-modified 18-mer oligonucleotide ((N)DNA) to form the QDs-(N)DNA nanosensor. In the presence of methylene blue (MB) as an intercalator, the hybridization of QDs-(N)DNA with the target BCR/ABL fusion gene (complementary DNA), brings the MB (acceptor) at close proximity of the QDs (donor), leading to FRET upon photoexcitation of the QDs. The enhancement in the emission intensity of MB was used to follow up the hybridization, which was linearly proportional to concentration of the target complementary DNA in a range from 1.0 × 10-9 to 1.25 × 10-7  M. The detection limit of the proposed method was obtained to be 1.5 × 10-10  M. Finally, the feasibility and selectivity of the proposed nanosensor was evaluated by the analysis of derived nucleotides from both mismatched sequences and clinical samples of patients with leukemia as real samples.