Porous and Dense Alginate/Chitosan Composite Films Loaded with Simvastatin for Dressing Applications

Alginate is a biocompatible polysaccharide matrix used for bioactive dressings with inherent healing properties. Most alginate dressings are produced as single-layer dressings. This study explores the potential of bilayer membranes to modulate drug release and enhance antimicrobial properties. We used alginate and chitosan loaded with simvastatin, an anti-inflammatory drug. One membrane comprised dense layers of both alginate and chitosan, while the other featured a dense alginate upper layer and a porous chitosan lower layer. The current study introduces a new approach in which a bilayer membrane is modeled instead of creating a polymeric blend between alginate and chitosan. The upper layer of the membrane contains only alginate loaded with simvastatin, while the bottom layer contains only chitosan. Another innovation is the study of the use of a porous lower layer of chitosan. Therefore, the association of these polymers in a bilayer and porous membrane gives advanced therapeutic dressings (with anti-inflammatory and antimicrobial properties intrinsic to the membrane) that are more efficient in the healing of complex wounds. Comprehensive characterization encompassed physicochemical, thermal, morphological, and mechanical properties. Microbiological tests were conducted using chitosan extract, and cytotoxicity evaluations were performed on fibroblast and keratinocyte cells. The results showed interlayer adhesion due to ionic interactions between alginate and chitosan surfaces. The drying process influenced the morphological and physicochemical features of the membranes. Simvastatin release profiles demonstrated sustained release over an extended period (approximately 60%–70% of the drug after 96 h). Storage assessments revealed that after six months, the membranes maintained around 98% of the initial simvastatin content. The antimicrobial activity test underscored the bacteriostatic efficacy of the chitosan porous layer, making it well-suited for infected wounds. Cell viability tests confirmed the non-cytotoxic nature of the films, highlighting their promising characteristics for treating diverse skin lesion types.