PREPARATION OF HOLLOW POLYELECTROLYTE MICROCAPSULES AND THEIR FLUORESCENT PROTEINS LOADING

Abstract

Hollow polyelectrolyte microcapsules with size around 4 ～ 5 μm,have been prepared by layer-by- layer ( LbL) adsorption technique,based on template of weakly crosslinked melamine formaldehyde ( MF) latex microspheres. In the presence of aqueous HCl solution ( pH = 1. 0),the MF cores are decomposed and hollow polyelectrolyte microcapsules are acquired. This kind of microcapsules can be utilized in many fields such as biosensor,drug release. Therefore,understandings on loading,penetrability of biomelocules on cell size microcapsules and their interaction with capsules are important,which are definitely favorable to their employment in real industry. In this study,R-phycoerythrins( R-PE) are used as a model to examine protein load behaviors and protein-capsules interaction. The R-PE is a kind of phycobiliprotein,which is found in red algae. It plays a crucial role in efficiently harvesting sunlight and then transfers this energy via a series of energy transfer mechanisms to chrolophyll in the membranes of photosynthetic organisms. The fluorescent intensity of R-phycoerythrin is compared before and after mixing with microcapsules where the pH value ranges at 3 ～ 10. It shows a maximum protein loading at pH 4 ～ 5. Moreover,the pH dependent protein loading of microcapsules is analyzed on laser scanning confocal microscope. The further results indicate some R- phycoerythrin is entrapped into capsules at pH 4 ～ 5. However,the R-phycoerythrin mainly adsorbs at the surface of the microspheres at a pH range of 6 ～ 10 and has a constant amount. It attributes microcapsules to have porous structure and high surface free energy. The capsules have a very poor protein loading amount at pH 3.