Encapsulation of magnetic nanoparticles in a pH-sensitive poly(4-vinyl pyridine) polymer: A step forward to a multi-responsive system

A multiresponsive system that consists on pH-responsive polymer microspheres with encapsulated iron oxide magnetic nanoparticles that rendered the core magnetic to enable externally controlled actuation under magnetic induction has been developed. The inorganic nanoparticles were first prepared and, then, further encapsulated in a pH-sensitive poly(4-vinylpyridine). These spheres have been obtained by a modification of the simple, rapid and high-reproducible nanoprecipitation method. Magnetic measurements showed that the iron oxide nanoparticles are superparamagnetic and, therefore, able to undergo a local increase of the temperature when an oscillating magnetic field is applied. Magnetically triggered heating and pH sensitivity can be useful for biomedical applications.This work has been supported by the Spanish Ministerio de Ciencia e Innovación (MICINN) and FEDER, Project MAT 2007-61621 and Consolider-Ingenio en Nanociencia Molecular ref. CSD 2007-00010. GI gratefully acknowledges Juan de la Cierva program. AA acknowledges the grant from the FPI program of the MICINN of Spain, project Mat2004-03395-C02-01. AU thanks the European Network MAGMANet for her scholarship.Peer Reviewe