Copper–PLLA-Based Biopolymer Wrinkle Structures for Enhanced Antibacterial Activity

The increasing prevalence of antibiotic-resistant bacteria has intensified the need for innovative antibacterial surfaces, particularly in biomedical applications. Traditional approaches often rely on chemical agents alone, which may lead to diminishing efficacy over time. To address this, we investigated the development of a novel antibacterial surface by combining the inherent antimicrobial properties of copper with an engineered surface topography on a biopolymer matrix. A copper-poly-L-lactic acid (Cu-PLLA) composite system was fabricated using sputtering deposition followed by controlled thermal treatment to induce wrinkle-like micro- and nanostructures on the surface. The surface morphology was characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), confirming the formation of hierarchical wrinkle patterns. The chemical composition and distribution of copper were analyzed via energy-dispersive X-ray spectroscopy (EDS). Antibacterial performance was assessed against both Gram-negative <i>Escherichia coli</i> and Gram-positive <i>Staphylococcus aureus</i> using standard colony count reduction assays. The Cu-PLLA wrinkled surfaces demonstrated significantly enhanced bactericidal activity compared with flat PLLA and copper-free controls, a finding attributed to a synergistic effect of mechanical membrane disruption and copper-mediated chemical toxicity. These findings suggest that biopolymer-metal hybrid surfaces with engineered topography offer a promising strategy for developing next-generation antibacterial materials suitable for biomedical and clinical use.