Towards macrophage-oriented Antituberculosis therapy: nanohydrogel and liposomal delivery of rifampicin-berberine Co-nanocrystals for enhanced intracellular Antituberculosis activity.

Tuberculosis (TB) remains a major global health threat, compounded by prolonged treatment regimens, drug toxicity, and the emergence of multidrug-resistant Mycobacterium tuberculosis strains. In this study, we present a novel therapeutic strategy integrating co-crystallization and nanocarrier engineering to enhance the intracellular delivery and antimicrobial efficacy of rifampicin and berberine. Rifampicin-Berberine (RIF-BBR) co-crystals were synthesized via solvent-assisted grinding, and their formation was confirmed through PXRD, NMR, FTIR, DSC, TGA, and TEM analyses, revealing a new crystalline phase stabilized by non-covalent interactions and improved physicochemical properties. The co-crystal was subsequently encapsulated into chitosan-based nanohydrogels and liposomes, yielding nanocarriers with high entrapment efficiencies, favorable particle sizes, and enhanced colloidal stability. In vitro drug release studies demonstrated pH-responsive and sustained release from the nanohydrogel system, while the liposomes exhibited an initial burst release suited for rapid drug availability. Antimicrobial evaluation against M. tuberculosis H37Rv showed that the nanoformulated co-crystal significantly improved inhibitory and bactericidal activity compared to free rifampicin, berberine, and the co-crystal alone, with the liposomal formulation displaying the lowest MIC and MBC values. Collectively, these findings underscore the potential of combining co-crystal engineering with nanocarrier-based delivery to overcome the limitations of conventional TB therapy. This dual strategy enhances intracellular drug accumulation, potentiates antimicrobial activity, and provides a promising foundation for developing more effective, targeted, and patient-compliant anti-tuberculosis treatments.