Multi-responsive copolymer gated magnetic mesoporous composite and simultaneous controlling of stimuli to maximize release of encased guest molecules

Abstract This research is aimed at designing a multi-/dual-responsive copolymer gated mesoporous composite microcapsule that allows regulated and efficient release of active molecules. Temperature and pH are the two important physiological parameters. In this investigation, both these physiological parameters are simultaneously regulated to achieve high release of loaded cargo molecules. Here, mesoporous magnetic mFe3O4/mSiO2 core-particles are modified with a copolymer gate via seeded radical copolymerization of 2-carboxyethyl acrylate (CEA) and N-isopropylacrylamide (NIPAM). The composite is referred as mFe3O4/mSiO2/P(NIPAM–CEA–MBA), where N,N'-methylenebisacrylamide (MBA) is a cross-linker. The composite surface is mesoporous with average pore diameter of around 3 nm and is highly paramagnetic (43.08 emu g−1). The copolymer gate showed both temperature- and pH-responsive phase transitions. Accordingly, the release of encased biomolecule and drugs using lysozyme (LZ), vancomycin (VC) and clonazepam (CZ) is further executed through optimized simultaneous control of temperature and pH. The release efficiency of LZ, VC and CZ reached 98%, 91% and 97% and the release rate followed the first order kinetics. The synthesized composite up to 0.5 mg ml−1 is found suitable for therapeutic in vivo application. The overall analyses suggest that the composite prepared can be safely used as microcapsule, a carrier-based release platform, for drug molecules.