Femtosecond laser-induced modification of PLLA/hydroxyapatite composite

In the article, we present the surface modification method of poly(L-lactide)/hydroxyapatite hybrid material using ultrashort pulse/femtosecond laser for tissue engineering application. Using femtosecond laser ablation we obtained 3D grooved structures at the composite surface with precisely controlled dimensions having 50-100 mu m in width and a depth of 20 mu m with porous bottom. Differential scanning calorimetry and XRD showed no significant influence of laser process on the supramolecular structure of the polymer in composite after modification. ATR analysis revealed partial surface "amorphisation" due to extremely high temperature gradient provided by laser pulses and relatively long crystallization time of PLLA. GPC revealed decrease in molecular weight of PLLA in the composite after laser modification. In addition biological tests were conducted. Human osteoblasts ATCC CRL-11372 were cultured on the laser-modified surface. Cytotoxicity and real time cell growth experiments showed no toxic effects of laser treated material on cells. This implies that femtosecond laser surface treatment is a promising method which potentially can be used in tissue engineering for scaffold modification and facilitating integration of bioresorbable implant and bone.