The influence of hydroxyapatite content on properties of poly(L-lactide)/hydroxyapatite porous scaffolds obtained using thermal induced phase separation technique

In the research we obtained porous scaffolds based on poly(L-lactide) and synthetic hydroxyapatite (HA) using thermal induced phase separation technique (TIPS) supported by salt leaching process (SL). The obtained series of composite foams differ in hydroxyapatite content (10, 25, 50, 75, 90 wt% of the HA in PLLA/HA systems). The investigated scaffolds porosity ranged from 88 to 98%, density from 0.024 to 0.140 g/cm(3). Water contact angle measurements indicated more hydrophilic scaffold surface with increasing hydroxyapatite content in the composites. Thermogravimetric analysis revealed higher thermal stability of all composites comparing to neat PLLA, indicated presence of similar to 3 wt% residual sodium chloride in the scaffolds. Differential scanning calorimetry analysis showed nucleation effect of hydroxyapatite and higher crystallinity of PLLA in the composites as compared to the neat PLLA. The above tests were supplemented with compressive strength measurements, which showed an increase in the Young's modulus and compressive stresses values parallelly with the increase of the filler content. Proliferation tests of MC3T3-E1 mouse calvaria pre-osteoblast cells indicated directly proportional relationship between hydroxyapatite content and cells proliferation rate.