Synthesis and Characterization of Poly(vinylphosphonic acid-co-acrylic acid) Copolymers for Application in Bone Tissue Scaffolds

Poly(vinylphosphonic acid-co-acrylic acid) (PVPAco-AA) has recently been identified as a possible candidate for use in bone tissue engineering. It is hypothesized that the strong binding of PVPA-co-AA to calcium in natural bone inhibits osteoclast activity. The free radical polymerization of acrylic acid (AA) with vinylphosphonic acid (VPA) has been investigated with varying experimental conditions. A range of copolymers were successfully produced and their compositions were determined quantitatively using P-31 NMR spectroscopy. Monomer conversions were calculated using H-1 NMR spectroscopy and a general decrease was found with increasing VPA content. Titration studies demonstrated an increase in the degree of dissociation as a function of VPA in the copolymer. However, a VPA content ca. 30 mol % was found to be the optimum for calcium chelation, suggesting that this composition is the most promising for biomaterials applications. Assessment of cell metabolic activity showed that PVPA-co-AA has no detrimental effect on cells, regardless of copolymer composition.