Magnetothermally Responsive Mesoporous Silica Nanocarriers: Materials Design, Thermoresponsive Gates and Controlled Drug Release

Abstract

Magnetothermally responsive nanocarriers represent a promising platform for spatio-temporally controlled drug delivery by combining alternating magnetic field (AMF)-induced heating with thermally triggered cargo release. Among the available architectures, magnetite-core/mesoporous-silica-shell (Fe3O4@mSiO2) nanoparticles functionalized with thermoresponsive polymer gatekeepers are particularly attractive. These systems integrate a magnetic heat source, a mesoporous drug reservoir, and temperature-dependent control of pore accessibility. This review examines the fundamental principles of magnetic hyperthermia, including heat-generation mechanisms, specific absorption rate (SAR), intrinsic loss power (ILP), AMF parameters and safety, and the interplay between Néel and Brownian relaxation. It also critically discusses core–shell synthesis and architecture, drug-loading strategies, PNIPAM-, PNVCL-, and other LCST-type gatekeepers, and the physicochemical characterization required to validate the complete nanocarrier. Evidence for combined magnetic hyperthermia and chemotherapy is assessed together with hemocompatibility, immunogenicity, oxidative stress, biodistribution, degradation, long-term retention, and clearance. Although promising magnetothermal release and therapeutic effects have been reported, evidence remains dominated by in vitro studies, with limited in vivo validation. Current clinical experience concerns locally administered iron-oxide hyperthermia rather than complete thermoresponsive Fe3O4@mSiO2 drug-delivery systems. Translation will require standardized magnetothermal and release testing, reproducible scale-up, validated sterilization and endotoxin control, component-resolved pharmacokinetics, and integrated development of the nanocarrier and AMF applicator.