Development of materials based on calcium polyphosphate/alginate for bone cement applications

Calcium phosphate based materials are biocompatible and chemically similar to hydroxyapatite, the main component of bone tissues.1,2 We prepared different composites based on sodium polyphosphate, sodium alginate and calcium chloride by dissolving both polymers in aqueous medium at 80oC and adding Ca2+ ions under vigorous stirring. The TGA of the dried composites showed 60-75% of alginate incorporation while Raman spectroscopy/microscopy revealed the characteristic vibrational frequencies of the polymer and the polyphosphate anion (Fig.1(a)). The morphology of the materials examined by SEM shows that the CPP particles are composed of crystalline flakes (Ca/P1) (Fig.1(b)) while the final CPP/alginate composites show a unique pattern, suggesting the coating of the micrometer sized crystals by a film of calcium alginate (Fig1(c)). The X-Ray diffraction pattern of CPP present a great crystallinity with no distinguishable phase, while the composites present a more amorphous pattern. The overall results show that these composites are promising bone substitute materials.