Enzymatic etching of PLA/hydroxyapatite scaffolds for improved cell adhesion: surface modification and homogeneity

Abstract

Nanosized hydroxyapatite (HAP) particles were produced by precipitation, and poly(lactic acid) (PLA) composites containing 5 wt% of the nano HAP were prepared in an internal mixer to prepare scaffold materials. The nanoparticles aggregated without surface modification. Applying stearic acid coating on HAP particles decreased aggregation and improved homogeneity. The extent of coating must be optimized, the amount of stearic acid needed for monolayer coverage is around 4 wt% for the HAP prepared. A polymer layer always forms on the surface of PLA products during the melt processing of PLA/HAP composites, HAP particles are not available to help bone regeneration. The surface layer was removed successfully by enzymatic etching. The amount of removed PLA polymer depended quite strongly on the extent of surface coating. Etching disclosed the HAP particles, which led to increased surface roughness and decreased wettability, but this did not influence the adhesion of cells on the surface. Scaffolds could be prepared successfully by 3D printing from the composites containing the coated particles, which, in all probability, can be successfully used for bone regeneration.