Preparation of Calcium Phosphate-Biodegradable Polymer Composites with Ion-Releasing Ability for Enhancing Bone Formation

Abstract

An inorganic-organic composite consisting of biorebsorbable β-tricalcium phosphate (β-TCP) and a biodegradable polymer is one of the most important materials for artificial bone with good shapability. In the present work, in order to activate bone-forming cells immediately after being implanted in a living body, a function for releasing therapeutic ions was incorporated to the composite. A small amount (8 vol%) of 46.1SiO₂·24.4Na₂O/MgO·26.9CaO·2.6P₂O₅ (mol%) glass particles was embedded successfully in the composite. When the glass particles containing Na₂O were included in the composite, the molecular weight of the polymer as the matrix phase was severely reduced and its hydrolysis in Tris-HCl buffer solution was drastically accelerated. On the other hand, when the glass particles containing MgO were included, therapeutic ions such as Ca²⁺, Mg²⁺, and silicate ions were continuously released with almost no change in the pH of the buffer solution. The release amount of silicate ions was well controlled, to avoid excessive dissolution, compared to those of Ca²⁺ and Mg²⁺ ions. The glass is one of the great promising candidates as a source in the composite for releasing therapeutic ions that enhance bone formation.