Magnetic nanoparticles encapsulated into biodegradable microparticles steered with an upgraded magnetic resonance imaging system for tumor chemoembolization.

In this work, therapeutic magnetic micro carriers (TMMC) guided in real time by a magnetic resonance imaging (MRI) system are proposed as a mean to improve drug delivery to tumor sites. MRI steering constraints and physiological parameters for the chemoembolization of liver tumors were taken into account to design magnetic iron-cobalt nanoparticles encapsulated into biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) microparticles with the appropriate saturation magnetization (M(s)). FeCo nanoparticles displayed a diameter of 182nm and an M(s) of 209 emicrog(-1). They were coated with a multilayered graphite shell to minimize the reduction of M(s) during the encapsulation steps. FeCo-PLGA microparticles, with a mean diameter of 58 microm and an M(s) of 61emicrog(-1), were steered in a phantom mimicking the hepatic artery and its bifurcation, with a flow in the same order of magnitude as that of the hepatic artery flow. The steering efficiency, defined as the amount of FeCo-PLGA microparticles in the targeted bifurcation channel divided by the total amount of FeCo-PLGA microparticles injected, reached 86%. The data presented in this paper confirms the feasibility of the steering of these TMMC.