A Nanoscale System for Remarkably Enhanced Drug Delivery Based on Hollow Magnetic Particles Encapsulated Within Temperature-Responsive Poly(methylmethacrylate)

A novel magnetic nanoscale drug delivery system, consisting of magnetic nanoparticles encapsulated by temperature-responsive poly(methylmethacrylate) (PMMA) with remarkably enhanced capabilities of controlled drug loading and release, is described. The carrier system is characterized by inner functionalized hollow magnetite nanoparticles and a surface conjugated smart polymer, which is temperature-responsive PMMA fabricated by polymerization of methylmethacrylate (MMA) on chemically surface-grafted hollow magnetite nanoparticles. The carrier nanocomposite was used as a drug carrier, p-aminosalicylic acid was used as a standard drug to investigate the drug delivery capability under conditions of variable temperature and pH. The results showed that the drug loading capacity was enhanced by the magnetic cavity structure, hydrogen-bonding interaction and temperature-responsive effect held by the hollow magnetic core and surface polymers. Furthermore, the drug loading ratio was about 1468.4 mu g (0.959 x 10(-5) mol) of standard drug per 0.0100 g of nanocomposite particles. On comparing the drug loading ratios with those reported in the literature, the achieved drug loading ratio was evidently increased by 12.8 times on average and by 38.7 times at most. Meanwhile, the drug delivery capability observed was that about 80% of the drugs incorporated in the drug delivery system was released within 3 to 4 hours, and the maximized drug release concentration exhibited a linear correlation with the release time. These findings proved that the nanotechnology-based drug delivery system established by a combination of hollow magnetic micro/nanostructures and temperature-responsive polymer encapsulation could efficiently raise the drug loading ratio. The proposed carrier system was appropriately suitable for magnetic targeted drug delivery with remarkably enhanced drug loading ratio, effective circulation time, and controlled drug release in response to changes of external temperature and pH.