Effect of Cu- and Zn-Doped Bioactive Glasses on the In Vitro Bioactivity, Mechanical and Degradation Behavior of Biodegradable PDLLA Scaffolds

Biodegradable polymer scaffolds filled with bioactive glass particles doped with therapeutic metal ions are a novel and promising strategy to repair critical-sized bone defects. In this study, scaffolds based on a poly (D, L-lactide acid) (PDLLA) matrix filled with un-doped and Cu-, Zn- and CuZn-doped bioactive glass particles were produced by freeze-drying and a salt-leaching method. The effects of the doping and content of the glass particles (10 and 30 wt.%) on the morphology, compression properties, apatite formation, and degradation behavior of the scaffolds were evaluated. The scaffolds presented high porosity (~93%) with pores ranged from 100 to 400 μm interconnected by smaller pores and this porosity was kept after the glass particles incorporation. The glass particles reinforced the polymer scaffolds with improvements as high as 130% in elastic moduli, and further promoted the apatite formation on the scaffold surface, both properties depending on the amount and type of filler. The bioactive glass particles boosted the scaffold degradation with the PDLLA/un-doped glass scaffold showing the highest rate, but still retaining structural and dimensional integrity. Our findings show that the incorporation of un-doped and metal-doped bioactive glasses increases the mechanical strength, promotes the bioactivity and modifies the degradation profile of the resulting polymer/glass scaffolds, making them better candidates for bone repair.