Development of a Highly Specific, Selective, and Sensitive Fluorescent Probe for Detection of Mycobacteria in Human Tissues.

Tuberculosis (TB), including extrapulmonary TB, is responsible for more than one million deaths in a year worldwide. Existing methods of mycobacteria detection have poor sensitivity, selectivity, and specificity, especially in human tissues. Herein, the synthesis of a cholic acid-derived fluorescent probe (P4) that can specifically stain the mycobacterium species is presented. It is shown that P4 probe specifically binds with mycobacterial lipids, trehalose monomycolate, and phosphatidylinositol mannoside 6. P4 probe can detect mycobacteria in polymicrobial planktonic cultures and biofilms with high specificity, selectivity, and sensitivity. Moreover, it can detect a single mycobacterium in the presence of 10 000 other bacilli. Unlike the probes that depend on active mycobacterial enzymes, the membrane-specific P4 probe can detect mycobacteria even in formalin-fixed paraffin-embedded mice and human tissue sections. Therefore, the ability of the P4 probe to detect mycobacteria in different biological milieu makes it a potential candidate for diagnostic and prognostic applications in clinical settings.