Systematic investigations of calcium phosphates produced by wet chemistry method and supercritical processing techniques

Abstract

Calcium phosphate (CaP) based material, especially hydroxyapatite (HAp) nanoparticles have a wide range of applications in a number of fields, such as drug delivery, gene therapy, bone cements, dental applications, chromatography and waste water remediation. Depending on the application, there is often a need for the nanoparticles to be in a particular size range. One of the potential applications of HAp is for drug delivery; as a transfection vector in specific. The main aim of this study was to evaluate the potential of various produced CaP nanoparticles for this matter. The HAp and CaP nanoparticles in this study were systematically investigated and produced by several methods, firstly by the wet chemistry method of sol-gel, where the process conditions of varying its stirring rates and temperatures were taken into consideration; secondly by the supercritical fluid techniques of Gas Anti-Solvent (GAS) and Solution Enhanced Dispersion of Supercritical Fluids (SEDS), where the process conditions of varying the processing temperature, pressure and supply of antisolvent flowrate were investigated. Lastly, several phases of CaPs were produced by a systematic investigation of CaP precipitation processes (via direct precipitation method and SEDS processing technique) by varying the Ca/P ratios. The processing conditions such as the stirring rate, temperature, pressure and antisolvent flowrate played a significant role on the nanoparticle size and morphology.