Introduction of Cation Species to Starch-reinforced Calcium Phosphate Bone Paste

Abstract

Bone cement is applied to bone detect caused by injury and disease. Our group has developed a novel bone paste by kneading a gelatinized wheat starch and calcium phosphate (CP) powders in which CaHPO₄, Ca₄(PO₄)₂O and β-Ca₃(PO₄)₂ are equimolarly mixed. This bone paste is easily handled and can be set to form hydroxyapatite (HAp) under physiological conditions. On the other hand, previous literature reported that strontium ion can promote and regulate the activity of osteoblastic and osteoclastic cells in the living bone, respectively. In addition, copper ion is reported antibacterial performance. In this work, strontium and copper ions were fed into the bone paste as starting materials to promote cell activity as well as antibacterial properties. Paste samples were prepared by kneading a starch gelatinized with mixed powders of CP, α-SrHPO₄ and Cu²⁺-substituted β-Ca₃(PO₄)₂. Phase change, release behavior of metal cations and antibacterial properties were investigated. A paste sample immersed in Tris-buffered NaCl solution was set through forming HAp, and the amount of strontium ion released from the paste sample was a level expected to enhance the cell activity. However, all the pastes didn’t show antibacterial properties in spite of introducing of copper ion to the samples.