Fabrication of hydrogel-encapsulated silica core bound with chitosan chains for efficient drug delivery

Abstract

In this study, hydrogel-encapsulated silica nanoparticles were facilely prepared through the following three consecutive steps: i) silica nanoparticles (SNPs) were synthesized via a sol-gel reaction of tetraethyl orthosilicate (TEOS) with ammonium hydroxide, ii) the resulting SNPs were functionalized with 3-(trimethoxysilyl)-propylmethacrylate (TPM) ligand with an olefin group, and iii) the TPM-functionalized SNPs were encapsulated with poly(N-isopropylacrylamide-co-acrylic acid), NIPAM-co-AAc hydrogels by using a radical polymerization reaction of the comonomers at the following ratio: NIPAM : AAc = 91 : 9 wt %. The lower critical solution temperature (LCST) of the encapsulated hydrogels with a moiety of carboxylic groups was slightly above physiological temperature and they demonstrated a thermo-sensitive variation of particle size. The hydrogel-encapsulated SNPs (SNPs@Hyd) were finally bound with chitosan chains, which are bio-friendly and non-toxic polymers. When compared to SNPs@Hyd, chitosan-coated SNPs@Hyd (SNPs@Hyd@Chi) exhibited prolonged drug (ibuprofen) release and stable structural integrity during the release test. (C) 2016 The Japan Society of Applied Physics