Chitosan/iota-carrageenan/curcumin-based materials performed by precipitating miscible solutions prepared in ionic liquid

Abstract

Curcumin (CUR) is a hydrophobic drug which has been loaded into polymeric carrier matrices by using experimental strategies with many steps, as well as by using conventional and volatile organic solvents. For the first time, this study reports the use of an ionic liquid ([Hmim][HSO4−]) to solubilize polycation-polyanion polymer pairs and hydrophobic CUR in the same system. By using the [Hmim][HSO4−] as an appropriated solvent, CUR (ca. 10% wt) is loaded into a polyelectrolyte complex (PEC) based on chitosan and commercial iota-carrageenan, following a straightforward method (in-situ approach). A solution containing chitosan, iota-carrageenan, and CUR is produced in [Hmim][HSO4−] and subsequently precipitated in an ice-water bath to form the CUR-loaded PEC. The ionic liquid is synthesized following a straightforward experimental route, and after PEC production, it is recovered and reused. X-ray photoelectron spectroscopy analysis shows that chitosan and iota-carrageenan are principally interacting by coulombic forces. Also, X-ray photoelectron spectroscopy and infrared spectroscopy analyses confirm that CUR is loaded into the PEC structure. Wide-angle X-ray scattering, scanning electron microscopy, and differential scanning calorimetry also confirm that CUR loaded PEC (ca. 105 mg g−1) comprise a more disorganized structure when compared to the pristine drug. The CUR is released in simulated gastric fluid (SGF, pH 1.2) because the PEC material increases 3.3-fold its solubility in SGF when compared to the raw curcumin. The ionic liquid can remain in the PEC structure, potentially imparting cytotoxicity. A simple aqueous washing step is sufficient to remove the residual [Hmim][HSO4−] and promote cytocompatibility. Cell viability assay performed on bone marrow-derived stem cells demonstrates that CUR significantly increases the cell viability promoted by the PEC.