Multitask Imidazolium Salt Additives for Innovative Poly(L-lactide) Biomaterials: Morphology Control, Candida spp. Biofilm Inhibition, Human Mesenchymal Stem Cell Biocompatibility, and Skin Tolerance

Candida species have great ability to colonize and form biofilms on medical devices, causing infections in human hosts. In this study, poly(l-lactide) films with different imidazolium salt (1-n-hexadecyl-3-methylimidazolium chloride (C₁₆MImCl) and 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C₁₆MImMeS)) contents were prepared, using the solvent casting process. Poly(l-lactide)-imidazolium salt films were obtained with different surface morphologies (spherical and directional), and the presence of the imidazolium salt in the surface was confirmed. These films with different concentrations of the imidazolium salts C₁₆MImCl and C₁₆MImMeS presented antibiofilm activity against isolates of Candida tropicalis, Candida parapsilosis, and Candida albicans. The minor antibiofilm concentration assay enabled one to determine that an increasing imidazolium salt content promoted, in general, an increase in the inhibition percentage of biofilm formation. Scanning electron microscopy micrographs confirmed the effective prevention of biofilm formation on the imidazolium salt containing biomaterials. Lower concentrations of the imidazolium salts showed no cytotoxicity, and the poly(l-lactide)-imidazolium salt films presented good cell adhesion and proliferation percentages with human mesenchymal stem cells. Furthermore, no acute microscopic lesions were identified in the histopathological evaluation after contact between the films and pig ear skin. In combination with the good morphological, physicochemical, and mechanical properties, these poly(l-lactide)-based materials with imidazolium salt additives can be considered as promising biomaterials for use in the manufacturing of medical devices.