A perfect stimuli-responsive magnetic nanocomposite for intracellular delivery of doxorubicin

Iron oxide nanoparticles (IONs) have been extensively applied in cancer therapy and theranostics due to their admissible magnetic properties, excellent chemical stability and biocompatibility. Herein, a novel stimuli-responsive magnetic nanocomposite was synthesized for cancer therapy; thereby, the triblock copolymer of poly[(2-succinyloxyethylmethacrylate)-b-(N-isopropylacrylamide)-b-dimethylaminoethylmethacrylate) [poly(SEMA-b-NIPAM-b-DMAEMA)] was prepared by reversible addition of fragmentation chain transfer (RAFT) polymerization. This triblock copolymer with carboxylic groups of succinyloxyethylmethacrylate was adsorbed onto the surface of Fe₃O₄ nanoparticles. The morphology, nanocomposite properties and stimuli-responsive behaviours were investigated by field emission scanning electron microscopy, X-ray diffraction, dynamic light scattering, vibrating sample magnetometer (VSM) and thermogravimetric analysis. Doxorubicin (DOX) encapsulation efficacy was 94.3%. Release behaviours of DOX from the magnetic nanocomposite exhibited that the rate of DOX release could be efficiently controlled through temperature and pH. The cytotoxicity of the drug was investigated in vitro against breast cancer cell line (MCF7) using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assays, 4',6-diamidino-2-phenylindole (DAPI) staining and cellular uptake. In conclusion, the synthesized DOX@nanocomposite can be applied in theranostic applications and anticancer drug delivery owing to admissible properties.