Amino modified core-shell mesoporous silica based layered double hydroxide (MS-LDH) for drug delivery

A layered double hydroxide-mesoporous silica core-shell nanostructure (LDH@mSiO(2)) with perpendicularly-oriented mesochannels was synthesised using a surfactant-directing method and modified with amine functionality for drug delivery applications. Mg/Al-layered double hydroxide (Mg/Al-LDH) materials with a disc-like morphology were synthesised and then coated with mesoporous silica (Mg/AILDH@mSiO(2)) via the functionalisation of (3-aminopropyl)triethoxysilane using a post-synthesis route (NH2-Mg/Al-LDH@mSiO(2)). The materials were characterised using a range of techniques. The Mg/AlLDH@mSiO(2) and NH2-Mg/Al-LDH@mSiO(2) materials possessed a spherical morphology and good porosity. Ibuprofen (IBU) and ciprofloxacin (CIPRO) were loaded into the pore channels of the NH2-Mg/Al-LDH@mSiO(2) and the release properties were examined at pH 4.0 and 7.4. The delayed release property exhibited by NH2-Mg/Al-LDH@mSiO(2) was attributed to the strong interactions of the drug molecules with the surface amino functionality and the charged LDH surface. The release profile from NH2-Mg/Al-LDH@mSiO(2) was also compared with that of the Mg/Al-LDH@mSiO(2) system under identical conditions. The porosity and functionalisation of the mesoporous silica shell and the surface charge density of the layered structure of Mg/Al-LDH are the major reasons for the controlled release of the cargo molecules. Moreover, the favourable delay in drug release from both materials at pH 4 was attributed to the higher level of ionisation and dissolution than at pH 7.4. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.