Hydrogen peroxide filled poly(methyl methacrylate) microcapsules: potential oxygen delivery materials

This paper describes the synthesis of H₂O₂-H₂O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O₂ delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ∼5 to 30 μm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H₂O₂-H₂O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H₂O₂-loaded microcapsules show that ∼70% of the H₂O₂ releases in 24h. This corresponds to a total O₂ production of ∼12 cc/gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ∼84 wt% of the initially loaded H₂O₂ after nine months storage at 2-8 °C, which is an attractive feature for clinical applications.