Functionalized poly L-lactic acid synthesis and optimization of process parameters for 3D printing of porous scaffolds via digital light processing (DLP) method

In the present study, Poly L-lactic acid (PLLA) resin compatible with digital light processing (DLP) 3D printing method was synthesized to produce hard tissue scaffolds. PLLA has been chosen as a decent material to mimic biological structures due to its relatively high strength as well as proper biocompatibility and biodegradation rate. After synthesis and functionalization of PLLA, using a facile method, porous models with 600-micron pore size and 70 % nominal porosity were designed and fabricated via DLP technique in order to investigate the effects of the two process parameters, light exposure time and dye concentration, on compressive strength and morphological features of the printed samples. The experimental results were then reconciled with plotted working curves for each dye concentration to validate the defined exposure time levels. It was concluded that the synthesized polymer and the used method of 3D printing are suitable for fabricating scaffolds with intricate structures. Moreover, by conducting the compression test, a maximum 2.2 MPa strength was achieved for the sample with minimum dye concentration and maximum exposure time. From the biological point of view, no cytotoxic effect was seen after a 3-day in vitro cell viability testing. Altogether, it was shown that optimal adjustment of the process parameters is essential to achieve appropriate dimensional and mechanical properties, which were acknowledged by plotted working curves.