Surfactant-driven microtopographies on the surface of PLA-Mg films for antibacterial applications

• Surfactant incorporation induces well-defined and reproducible microtopographies on PLA film surfaces. • Anionic, cationic, and non-ionic surfactants generate distinct surface morphologies with different roughness and wettability • CTAB- and SDS-modified PLA films exhibited strong antibacterial activity against Staphylococcus epidermidis • Magnesium incorporation enhanced antibacterial performance and suppressed viable biofilm formation on selected surfaces. • T20-containing PLA films supported keratinocyte adhesion and proliferation while reducing bacterial adhesion. The development of bioabsorbable biomaterials with surface properties that promote tissue integration while preventing bacterial colonization remains a major challenge in biomedical engineering. In this study, polylactic acid (PLA) films with tailored surface microtopographies were fabricated through a simple and scalable solvent casting approach by incorporating surfactants with different chemical natures: sodium dodecylsulphate (SDS), hexadecyltrimethylammonium bromide (CTAB) and polysorbate 20 (Tween-20, T20). Magnesium particles were also incorporated as a biodegradable antibacterial additive and to improve the mechanical behaviour of PLA. Surface morphology and topography were analyzed by atomic force microscopy and optical profilometry, while wettability and surface free energy were assessed by contact angle measurements. The biological performance of the films was evaluated using Staphylococcus epidermidis adhesion and biofilm formation assays, together with cell viability studies employing HaCaT human keratinocytes. Distinct and reproducible surface microstructures were generated depending on the surfactant employed, including conical protrusions, isotropically distributed microcavities, and spiral-like patterns. Surfactant incorporation reduced bacterial adhesion relative to pristine PLA, an effect further enhanced by magnesium addition, which led to the total inhibition of viable biofilms on CTAB- and SDS-containing samples. In contrast to samples incorporating CTAB or SDS, T20-modified PLA supported keratinocyte adhesion and long-term viability, even in the presence of magnesium. These results establish surfactant-induced microstructuring as a powerful and unexplored strategy for modulating the biological response of PLA, opening new avenues for the design of bioabsorbable biomedical devices for wound healing.