Versatile pH-Responsive Chitosan-g-Polycaprolactone/Maleic Anhydride-Isoniazid Polymeric Micelle To Improve the Bioavailability of Tuberculosis Multidrugs.

The potential of polymeric micelles constructed by coalescing natural and synthetic polymers for tuberculosis (TB) treatment was evaluated in this work. We designed a polymeric micelle to improve the delivery of anti-TB drugs (rifampicin [RF] and isoniazid [INH]). The polymeric core was synthesized in the following order: initially chitosan (CS) was grafted with polycaprolactone (PCL) to form CS-g-PCL followed by amide bond formation with maleic anhydride-isoniazid (MA-INH); finally, CS-g-PCL was conjugated with the MA-INH moiety to form the CS-g-PCL/MA-INH polymeric core. Another anti-TB drug, RF, was loaded onto CS-g-PCL/MA-INH through dialysis. The changes in the nature of functional groups and crystallinity were investigated by Fourier transform infrared spectroscopy and X-ray diffraction analysis, respectively. The shape and size of CS-g-PCL/MA-INH and RF-CS-g-PCL/MA-INH were analyzed by dynamic light scattering, scanning electron microscopy, and transmission electron microscopy. The cumulative drug release profiles were measured by UV-visible spectrophotometry and HPLC analysis. The antimicrobial activity of the loaded micelles was evaluated by finding the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bacterial cell rupture analyses. The nontoxic nature of the micelles was assessed by ex vivo studies on U937 and L929 cell lines and erythrocytes by performing an MTT assay, apoptosis assay, and hemolysis assay. Ex vivo cellular uptake and in vivo internalization of the INH- and RF-containing micelles were tested on U937 cells and zebrafish using fluorescence microscopy analysis. All of the observations indicate that the multi-TB drug-loaded polymeric micelle is a safe and effective system for the delivery of anti-TB drugs without affecting the mycobactericidal activity.