Redevelopment of polymeric encapsulants for delivery of chemical reactants

Abstract

Sodium percarbonate was incorporated in the PCL microcapsules to achieve sustained release of oxygen, with the goal of providing a viable source of oxygen for the prolonging tissue survival in wound healing and organ regeneration.

Encapsulation of water sensitive sodium percarbonate was achieved using oil-in-oil emulsion technique. Polycaprolactone serves as the polymeric shell and polyethylene glycol acts as the surfactant.

Scanning electron microscopy revealed that most of the particles are clumped together without any specific shape. This is partly due to the semi-crystalline nature of PCL and its low rigidity. In addition, agglomeration occurred throughout all the formulations, thus increasing the effective particle size. The effects of agglomeration could have been magnified by the high shear stress introduced by the homogenizer and the use of PEG 10,000 as the binder. Agglomeration is controlled by a wide variety of factors and altering them could reduce the effects of agglomeration.

In vitro timed water immersion test revealed that among the formulations used, using 10 wt% of PEG yielded better results. The microcapsules lasted for a longer duration (1 hour) as compared to other formulations (30 mins).

It was proposed that the release of oxygen was caused by PEG dissolving in water, which creates channels in the polymeric shell for water to diffuse in to react with sodium percarbonate and release oxygen. Oxygen may have escaped through these channels or accumulated within the microcapsule until it ruptures due to excessive pressure.