Abstract
This study deals with the synthesis and in vitro osteocompatibility evaluation of two novel alanineโcontaining biodegradable ester polyphosphazenes as candidates to form selfโsetting composites with hydroxyapatite (HAp) precursors. The two novel biodegradable polyphosphazenes synthesized were poly[(ethyl alanato)~1.0~(ethyl oxybenzoate)~1.0~ phosphazene] (PNโEA/EOB) and poly[(ethyl alanato)~1.0~(propyl oxybenzoate)~1.0~ phosphazene] (PNโEA/POB). The polymers were characterized by multinuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). Biodegradability and percentage water absorption of the polymers were evaluated by following the mass change in phosphate buffer (pH 7.4) at 37ยฐC. PNโEA/POB underwent faster degradation and showed higher water absorption compared to PNโEA/EOB. Both polymers became insoluble in common organic solvents following hydrolysis presumably due to crosslinking reactions accompanying the degradation process. Osteoblast cell adhesion and proliferation on PNโEA/EOB and PNโEA/POB was followed by scanning electron microscopy (SEM) and by using a biochemical assay. Both PNโEA/EOB and PNโEA/POB supported the adhesion and proliferation of primary rat osteoblast cells in vitro. Furthermore, the enzymatic activity of the osteoblast cells cultured on the polymers was confirmed by the alkaline phosphatase activity. Thus, these biodegradable aminoโacidโbased polyphosphazenes are promising new materials for forming selfโsetting bone cements. ยฉ 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006