Synthese neuartiger Verbundwerkstoffe für den Knochenersatz aus Calciumphosphaten, Calciumcarbonaten und Polylactiden und deren mechanische und biologische Eigenschaften

摘要

Biodegradable composite materials consisting of polylactide (PDLLA and PLLA), β-tricalcium phosphate (β-TCP), and calcium carbonate were developed as a novel bone substitute candidate aiming to manufacture 3D scaffolds via selective laser melting (SLM). Polylactide was chosen as a biodegradable, meltable and adhesive component. β-TCP was used because of its bone-like mineral phase, calcium carbonate for buffering the acidic degradation of the polylactide component. Critical aspects were a vast volumetric swelling and an accelerated degradation of the polymeric component during the SLM process. Concerning to processing, mechanical strength and bone-like properties the polymeric content was set to 60 wt%. The prepared test specimens indicated a bending strength up to 90 MPa. Because of a vast volumetric swelling the bending strength of PDLLA-containing specimens decreased about 60 vol% after storage of 8 weeks in phosphate buffer. A swelling and thus a volume increase could be critical, especially for using the tri-phase bone substitute compound as 3D scaffold with defined dimensions. The swelling of the specimens was almost completely prevented by using PLLA instead of PDLLA. The viability of human mesenchymal stem cells cultivated on PDLLA-based materials decreased due to the volumetric swelling, while the cells cultivated on PLLA-based materials indicated a good viability.