Design of Remote-Controllable\nDiels–Alder Platform\non Magnetic Nanoparticles via Layer-by-Layer Assembly for AC Magnetic\nField-Triggered Drug Release

Diels–Alder\nchemistry was exploited to develop a remote-controllable\ndrug release platform on magnetic nanoparticles (MNPs). For this purpose,\nMNPs were decorated with anionic poly(styrenesulfonic acid-<i>co</i>-furfuryl methacrylate) (poly(SS-<i>co</i>-FMA))\nand cationic poly(allylamine hydrochloride) by layer-by-layer assembly.\nThe decorated MNPs successfully underwent DA reaction to produce covalent\nbonding between FMA (diene) and maleimide (dienophile)-terminated\nmodel drug. Thermal treatment above 80 °C caused the retro Diels–Alder\nreaction (rDA) between FMA and the drug, resulting in drug release.\nThe retro DA could be also achieved by applying an alternating-current\n(AC) magnetic field to the decorated MNPs. This could spatially limit\nthe heat generation around MNP without heating entire system. Drug\nrelease could be also accelerated with the irradiation time when a\nthreshold temperature was met or exceeded the required energy for\nrDA reaction. Our results highlight the potential of DA chemistry\nas a new strategy to provide a remote controllable drug release platform\nfor improving the therapeutic efficiency.