Modified Castor Oil-Based Polyurethane Films with Streptomyces Extracts Presenting Anti-Methicillin-Resistant Staphylococcus aureus Activity

Methicillin-resistant S. aureus is a problematic pathogen due to its high-risk infections and resistance mechanisms. To fight against this bacterium, novel antimicrobial sources and new delivery systems must be developed. Antimicrobial polyurethanes for developing biomaterials can function as preventive strategies. In this study, we explore the synthesis of partially renewable polyurethanes as biomaterial carriers of novel antimicrobials. An antibacterial extract from a Streptomyces sp. strain and its inclusion complexes with β-cyclodextrin, used as an additional protective approach, were incorporated into castor oil-based polyurethane films through bulk or surface loading. The inclusion complexes were characterized to confirm host–guest interactions. The films were characterized by FTIR, XRD spectra, surface SEM images, hydrophilicity, thermal stability, and mechanical performance. FTIR suggested successful polyurethane synthesis. The polymers were semicrystalline and thermally stable until 260 °C, and Tg ranged between −16.9 and −9 °C. Bulk modification decreased the mechanical performance of the films. Surface modification promoted good antibacterial performance but cytotoxic potential against HDFa cells. However, PU active films showed favorable properties and hemocompatibility, making them a promising alternative for applications such as short-term dressings, serving as an antimicrobial delivery system and a preventive strategy against methicillin-resistant S. aureus.