Self-Assembly Multilayers Alginate/Chitosan Film Loaded with Alginate-Capped Silver Nanoparticles: A Promising Scaffold in Infected Skin Wound Scenarios

Cutaneous wound healing is a complex biological process often impaired by bacterial infections, especially by Staphylococcus aureus. To address this, alginate (ALG)/chitosan (CS) polyelectrolyte multilayer (PEM) films incorporating alginate-coated silver nanoparticles (ALG–AgNPs) were fabricated by layer-by-layer self-assembly. The films exhibited a porous, layered morphology with homogeneous distribution of ALG–AgNPs, hydrophilic surfaces (contact angle ≈ 55°), a high swelling degree (~175%), and a water vapor transmission rate of 1830 g m−2·day−1. Thermal analyses showed similar degradation profiles up to 600 °C, with the ALG–AgNP film displaying lower moisture loss and higher dehydration temperature, consistent with enhanced ionic and coordination crosslinking (–NH3+/–COO− and Ag–O–C bonds). The release of Ag+ in PBS (pH 7.4) was ~3% after 24 h, following a Korsmeyer–Peppas mechanism (R2 = 0.97, n < 0.5), and degradation, with ~40% mass loss in 6 days, indicated gradual matrix disintegration. Cytocompatibility studies revealed >80% viability for fibroblasts, keratinocytes, macrophages, and <2% hemolysis of red blood cells. Immune assays showed a tendency towards reduced TNF-α and IL-1β and regulated IL-6/IL-8 release. Antibacterial evaluations demonstrated a 5-log reduction in planktonic bacterial viability and >2-log reduction in adhesion, and an 11 ± 1 mm inhibition zone for S. aureus. These results demonstrate that ALG/CS–AgNP PEM films combine biocompatibility, antibacterial efficacy, controlled degradation, and structural stability, making them promising multifunctional scaffolds for the regeneration of infected skin wounds.