Narrowly dispersed double-walled concentric hollow polymeric microspheres with independent pH and temperature sensitivity

Abstract

Synthesis of double-walled concentric hollow polymeric microspheres of well-defined shape and narrow size distribution was demonstrated. It was observed that the poly(methacrylic acid) (PMAA) inner shell and the poly(N-isopropylacrylamide) (PNIPMA) outer shell responded independently to pH and temperature of the environment. The study used uniform silica-3- (trimethoxysilyl)propylmethacrylate (SiO2-MPS) composite microshperes having diameter of 290 nm and synthesized using sol-gel process, tetraethyl orthosilicate (TEOS), and MPs. The Donnan osmotic swelling caused the change in hydrodynamic diameter of the PMAA inner shell and the change in hydrodynamic diameter of PNIPAM outer shell was due to lower critical solution temperature behavior of the polymer. It was also observed that doxorubicin-loaded PMAA-PNIAPM hollow microspheres showed temperature and pH-controlled release of anticancer drug.