‘Cookies on a tray’: Superselective Hierarchical Microstructured Poly(L-lactide) Surface As a Decoy For Cells

In this research we developed a micro-sized hierarchical structures on a poly(L-lactide) (PLLA) surface. The obtained structures consist of round-shaped protrusions with a diameter of ~20 µm, a height of ~3 µm, and the distance between them ~ 30 µm. We explored the effect of structuring PLLA to design a non-cytotoxic material with increased roughness to encourage cells to settle on the surface. The PLLA foils were prepared using the casting melt extrusion technique and were modified using ultra-short pulse irradiation – a femtosecond laser operating at λ=1030 nm. A hierarchical microstructure was obtained resembling 'cookies on a tray'. The cellular response of fibro- and osteoblasts cell lines was investigated. The conducted research has shown that the laser-modified surface is more conducive to cell adhesion and growth (compared to unmodified surface) to such an extent that allows the formation of highly-selectively patterns consisting of living cells. In contrast to eukaryotic cells, the pathogenic bacteria Staphylococcus aureus covered modified and unmodified structures in an even, non-preferential manner. In turn, adhesion pattern of eukaryotic fungus Saccharomyces boulardii resembled that of fibro- and osteoblast cells rather than that of Staphylococcus. The discovered effect can be used for fabrication of personalized and smart implants in regenerative medicine.