Detection of unamplified mycobacterium tuberculosis genomic DNA in sputum samples using a metal-enhanced fluorescence-based biosensor.

Mycobacterium tuberculosis the development of a metal-enhanced fluorescence (MEF)-based biosensor in this study enabled the detection of Mycobacterium tuberculosis DNA extracted from sputum samples with high sensitivity and without the need for DNA amplification. The detection process involved the utilization of silver dendritic nanostructures, which were grown on the surface of silicon wafers and subsequently modified with a probe that was designed to target the specific DNA Insertion Element 6110 (IS6110) gene of M. tuberculosis. A comparison was made between the performance of the developed nanobiosensor and that of other methods, including smear, culture, PCR, and real-time PCR. A total of 385 (including 50 confirmed positive) sputum samples were examined. Of these, 8.8%, 10%, 11.9%, 13%, and 12% cases were confirmed positive by smear, culture, PCR, real-time PCR, and the developed nanobiosensor, respectively. The limit of detection was established at 2.9 × 102 copies for PCR and 2.9 × 10 copies for both real-time PCR and the nanobiosensor. The sensitivities of smear, culture, PCR, and the nanobiosensor, in comparison to GeneXpert MTB/RIF assay, were determined to be 68%, 78%, 86%, and 92%, respectively. The specificity of each method was 100%. The findings suggest that the developed nanobiosensor is a low-cost, accurate, and rapid tool for the detection of tuberculosis.