Detection of Mycobacterium Tuberculosis IS6110 gene fragment by fluorescent biosensor based on FRET between two-dimensional metal-organic framework and quantum dots-labeled DNA probe

Herein, a universal fluorescent biosensor was developed for detecting Mycobacterium Tuberculosis (MTB) specific insertion sequence IS6110 gene fragment based on Förster resonance energy transfer (FRET) strategy. CdTe quantum dots (QDs), with excellent luminous performance, were used to label single-stranded DNA (ssDNA) as fluorescence donor (QDs-DNA), in which the ssDNA was complementary to the IS6110 gene fragment. A new type of two-dimensional metal-organic framework (Cu-TCPP) was served as an acceptor. The Cu-TCPP exhibited a higher affinity towards ssDNA than double-stranded DNA (dsDNA). In the absence of targets, the fluorescence of QDs-DNA was quenched - due to the π-π stacking interactions between Cu-TCPP and ssDNA. Otherwise, QDs-DNA hybridized with the target to form a double helix and the fluorescence maintained in a target-concentration dependent manner. Excess QDs-DNA would be quenched and produced negligible background signal. The fluorescent sensor possessed a linear range from 0.05 nM to 1.0 nM with a low detection limit of 35 pM. Furthermore, we successfully applied this biosensing system to detect clinical sputum samples. This method displayed high sensitivity, specificity and great potentials in the early diagnosis of Tuberculosis.