A magnetic Bead-Quantum Dot (MB-QD) complex with a specific probe for Mycobacterium tuberculosis DNA detection

Schematic diagram of the DNA detection process of Mycobacterium tuberculosis with functionalized MB-QD complex. • The result of MB-QD is visualization. • This approach can detect TB patient-derived bacterial culture extracted DNA. • This method could serve as a reference strategy for point-of-care testing (POCT) in MTB detection. Tuberculosis (TB) still puts a lot of pressure on public health prevention and control, and traditional detection techniques are not only time-consuming but also rely on expensive instrumentation, so the development of a rapid detection method for TB is essential. In this study, we used Mycobacterium tuberculosis (MTB) gene CoaA as a template to design specific primers to be ligated with biotinylated magnetic beads (MBs) and quantum dots (QDs), respectively, to construct probe-MBs and probe-QDs. When the DNA template is MTB or in vitro -synthesized CoaA gene fragment, the probe-MBs and probe-QDs can be used to form MB-QDs with DNA template under certain reaction conditions. Form MB-QD complexes with DNA templates and red fluorescence can be observed at 365 nm. Our results showed that the MB-QD complex can be used to detect the DNA of the synthesized CoaA DNA fragment, MTB or DNA extracted from sputum of TB patients by bacterial culture, and red fluorescence can be observed by the naked eye at 365 nm. The complex has good stability, its detection is specific, it cannot recognize single-base or two-bases mismatches, and its detection sensitivity can be as high as 0.001 μM, with a detection rate of 79.2 % in clinical samples. CoaA is an essential gene in MTB, and this paper explores for the first time the possibility of CoaA as a target for MTB DNA detection, and also provides a new detection index and reference strategy for the point-of-care testing (POCT) detection of TB.