High performance biocompatible cellulose-based microcapsules encapsulating gallic acid prepared by inverse microsuspension polymerization

In this study, the preparation of biocompatible cellulose-based microcapsules encapsulating gallic acid (GA), an important antioxidant of Bambara groundnut extracts, by water-in-oil inverse microsuspension polymerization was studied. GA and carboxymethyl cellulose (CMC) were selected as core and shell materials, respectively. For high encapsulation efficiency, CMC was firstly modified (modified-CMC (m-CMC)) with 3-(trimethoxysilyl)propyl methacrylate (MPS) as a silane coupling agent. It was subsequently polymerized with methacrylic acid (MAA) monomer through a radical route, forming a PMAA grafted m-CMC (m-CMC-g-PMAA) biocompatible polymer shell. Using CMC:MPS in a ratio of 75:25 (w/w %), highly water-soluble m-CMC containing a C=C bond for further radical polymerization was obtained. After inverse microsuspension polymerization at various ratios of m-CMC:MAA, highly stable spherical m-CMC-g-PMAA microcapsules encapsulating GA were formed in all ratios. It was observed that the encapsulation efficiency increased with increase in MAA content. m-CMC:MAA in a ratio of 33:67 (w/w%) presented the highest encapsulation efficiency which may due to the increase of hydrophilicity of the aqueous phase. It also presented rapid release and non-cytotoxic characteristics, suited for use in cosmetic products. (c) 2018 Society of Chemical Industry