Balancing antibacterial effects and cytotoxicity through LIFT-fabricated AgNP microdomain arrays on PET

Here, we report the first systematic study of two distinct configurations of hexagonal silver nanoparticle (AgNP) microdomain arrays prepared on polyethylene terephthalate (PET) substrates using the laser-induced forward transfer (LIFT) technique. By varying the size and spacing of the domains, we investigated how geometric parameters govern nanoparticle distribution, surface morphology, and biological response. AFM, SEM, CLSM, EDX, and XPS analyses revealed a pronounced gradient of AgNP density across the patterned surfaces, with the highest roughness and nanoparticle aggregation in domain centers, reduced coverage at the edges, and detectable but sparse particles in inter-domain gaps. Cross-section TEM further confirmed that nanoparticles are confined to a thin surface layer, ensuring high biological availability while minimizing uncontrolled leaching. Antibacterial activity assessment revealed that both Staphylococcus epidermidis (Gram-positive) and Escherichia coli (Gram-negative) were reduced below the detection limit within two hours across all patterned surfaces, irrespective of domain size. Cytotoxicity tests using normal human dermal fibroblasts (NHDF) revealed that the cells adhered, proliferated, and remained metabolically active over a seven-day period, although their enzymatic activity and numbers were reduced compared to cells growing on pristine PET. These findings highlight the unique dual functionality of LIFT-fabricated AgNP microdomains, which exhibit rapid and broad-spectrum antibacterial activity, combined with good cytocompatibility. The demonstrated ability to tune surface architecture by controlling domain size and spacing offers a promising pathway toward advanced antimicrobial coatings for medical devices and implants.