Abstract
Calcium phosphate is attracting attention as a bone repair material and a controlled-release carrier of various drugs such as bone disease therapeutic agents and anticancer agents. Compared with some bioabsorbable polymers, calcium phosphates have the advantage of preventing a pH decrease in the surrounding body fluid. However, there are few studies comparing the effect of supporting substances with different physicochemical properties on the production of calcium phosphate microspheres with different crystalline phases. In this study, we investigated conditions for obtaining low crystallinity apatite and octacalcium phosphate (OCP) microspheres from calcium carbonate microspheres with different crystalline structures using a simple phosphoric acid treatment. Furthermore, we investigated the adsorption and release behavior of different dyes and proteins from the apatite and OCP microspheres. Overall, the factors governing the adsorption and release behavior are different depending on the molecular size and surface charge of the dye and protein adsorbates.
Highlights
Calcium phosphate is attracting attention as a bone repair material and a controlledrelease carrier for various drugs such as bone disease therapeutic agents and anticancer agents [1,2]
We investigated the conditions for obtaining microspheres consisting of low crystallinity apatite and octacalcium phosphate (OCP) from calcium carbonate microspheres with different crystalline structures using a simple phosphoric acid treatment
The crystalline phase after heat treatment of the vaterite microspheres was identified as a single phase of calcite by X-ray diffraction (XRD)
Summary
Calcium phosphate is attracting attention as a bone repair material and a controlledrelease carrier for various drugs such as bone disease therapeutic agents and anticancer agents [1,2]. Extensive studies have been conducted on bioabsorbable poly-lactic-co-glycolic acid microspheres for controlled drug release; inflammation by their acidic degradation products is a concern [4,5]. To address these concerns, calcium phosphate has been added to suppress the pH decrease during degradation [6], and the degradation rate of calcium phosphate microspheres has been controlled by additives such as Sr2+ [7]. Various studies using composite microspheres as scaffolds for vascular regeneration in ischemic diseases have been reported [8]
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