Controlled chemical synthesis of CaO2 particles coated with polyethylene glycol: Characterization of crystallite size and oxygen release kinetics

Abstract

Incorporating oxygen generating substances into tissue constructs is one of the methods for increasing cell survival under hypoxic condition. Calcium peroxide from alkaline earth metal peroxide groups has been proposed as an appropriate compound for supplying sufficient oxygen to cells within the scaffolds. The high surface-to-volume ratio of CaO2 particles can lead to an increase in oxygen generation ability over a particular time interval. One objective of this study was to decrease calcium peroxide crystallite size via changing the local supersaturation level by controlling the reactant addition rate during coprecipitation synthesis. Therefore, the effect of hydrogen peroxide addition rate on the crystallite size, particle size distribution, and CaO2 purity, which have not been studied before, were discussed. It was found that the crystallite size of CaO2 depends upon the reactant addition rate, and the crystallite size decreased from 111 to 37 nm when the addition rate increased from 0.29 to 0.88 ml min-1. Furthermore, after determining the hydrogen peroxide addition rate, a facile method was developed to prepare CaO2 particles with polyethylene glycol coating for the first time. The aim of PEG coating was to improve redispersion of the precipitated CaO2 particles. Thermogravimetric analysis was used to measure the content of adsorbed PEG on the surface of the particles. Eventually, the oxygen release profile of PEG-coated calcium peroxide particles demonstrated that the release kinetics is dependent on the pH value of the exterior medium, diffusion through the calcium carbonate product layer, and molar ratios of PEG to calcium.