The effect of selective mineralization of PLLA in simulated body fluid induced by ArF excimer laser irradiation: Tailored composites with potential in bone tissue engineering

In this paper we exposed samples of poly(l-lactide) (PLLA) extruded foil to ArF excimer laser (193 nm) radiation near the ablation threshold. The modified foil was immersed in the Simulated Body Fluid (SBF) at 37 °C for both short and long time (short term: up to 24 h, long term: up to four weeks). We described the physicochemical changes in PLLA before and after incubation in SBF. The laser irradiated PLLA incubated in SBF revealed turbidity on the irradiated surface. UV–Vis spectroscopy showed a remarkable decrease in transmittance for the irradiated PLLA incubated in SBF as compared to the non-irradiated PLLA incubated in SBF. Scanning electron microscopy proved the presence of minerals on the surface of PLLA in the laser irradiated area. The mineralization occurred only on the irradiated surface indicating that the process is selective. In the mineralized area a reduction of water contact angle was observed, suggesting a higher hydrophilicity of the surface. Moreover, a reduction in molecular weight was recorded in the long term incubation experiment for irradiated PLLA as compared to the unmodified sample. The samples were also investigated in terms of supramolecular changes in the material (DSC) and in terms of their thermal properties (TGA).