Microwave hydrothermal synthesis of calcium phosphates using inorganic condensed phosphate salts as precursors

Abstract

a b s t r a c tAs a potential phosphate source, inorganic soluble condensed phosphate salts represent a viable alternative to both orthophosphate and organic condensed phosphate salts. The present work demonstrates a simple but versatile microwave hydrothermal method to prepare calcium phosphates using pyrophosphate and tripolyphosphate salts. After 5-min microwave heating, white fine powders are precipitated from calcium and condensed phosphate containing solution. The as-synthesized precipitates are crystallized calcium pyrophosphate hydrate whiskers and calcium tripolyphosphate hydrate porous microspheres. After calcination, both ceramics are converted into calcium pyrophosphate. In vitro study reveals both precipitates and calcined powders are cytocompatible compared to microwave hydrothermally synthesized hydroxyapatite. With all of these attributes, it is expected different inorganic soluble condensed phosphate salts together with microwave can be used to generate a series of calcium phosphates with unique features.