A low-temperature hydrothermal approach to fabricate bactericidal nanostructures on 3D-printed polylactic acid surfaces against Pseudomonas aeruginosa bacteria

Surface modification offers the opportunity to create nano-topographies on various materials. Such modifications are widely applied to enhance solar energy absorption and electromagnetic shielding. An additional high-impact application involves nano-topographic surfaces designed to combat biofilm formation by nature inspired surfaces, such as cicada and dragonfly wings, which physically lyse bacterial cells. Such mechano-bactericidal surfaces have attracted growing interest over the past decade, and ongoing efforts translate these structures into medical and industrial applications. While considerable progress has been achieved with metallic and ceramic surfaces, advancements in polymers remain limited, despite their widespread use. In this study, a low-temperature hydrothermal approach successfully modified the 3D-printed polylactic acid (PLA) surface to nano-topographies. Although the literature describes a limited number of strategies for producing nanostructures on 3D metallic surfaces, fabricating such structures on 3D polymeric surfaces remains challenging using conventional methods. This study demonstrates the successful fabrication of distinct nanostructures on both the top and bottom surfaces of a 3D-printed PLA substrate. The produced surfaces were characterised via scanning electron microscopy (SEM), atomic force microscopy (AFM), SEM-Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The bactericidal efficacy (BE) was quantified via LIVE/DEAD™ BacLight™ bacterial viability assay with inverted fluorescence microscopy images. Among the developed structures, Nano-Pockets with an average pore diameter of ∼275 nm exhibited the highest BE, achieving a 48.8 % reduction in Gram-negative Pseudomonas aeruginosa viability within 1 hour of incubation. This approach, therefore, lays the foundation for fabricating nanostructures on 3D-printed polymeric surfaces with complex geometries.