Encapsulation of Ciprofloxacin into a Cyclodextrin Polymer Matrix: The Complex Formation with Human Serum Albumin and In Vitro Studies

Here, we propose a drug delivery system for ciprofloxacin (CF) based on cyclodextrin (CD) polymer. We obtained a 3D matrix system with encapsulated drug molecules by crosslinking CF+CD non-covalent complexes with 1.6-hexamethylene isocyanate. The obtained polycarbamide (MAX-system) represents particles (similar to 225 nm in diameter) that demonstrate CF's sustained release. We investigated how the carrier affects the drug's interaction with the biological macromolecule human serum albumin (HSA) and CF's antibacterial properties. Compared to a binary CF-HSA system, CD decreases CF's binding efficiency to HSA by two times, whereas CF encapsulation in a polymer matrix doubles the Ka value and prevents protein aggregation. The changes in HSA's secondary structure indicate no alterations in the main mechanism of complex formation between CF and HSA in the presence of both CD-based carriers. CD as well as MAX systems practically do not change CF's activity against E. coli and B. subtilis, but for MAX systems, prolonged action is realized due to CF's sustained release. We believe that our findings are important for the further development of new, efficient drug forms.