Nanostructuring the Surface of Dual Responsive Hollow Polymer Microspheres for Versatile Utilization in Nanomedicine-Related Applications

The design and fabrication of hollow polymer microspheres responsive to various stimuli comprises a promising approach for the development of multifunctional and efficient systems for various nanomedicine-related applications. In this paper, we present the preparation of poly(methacrylic acid-co-N,N'-methylenebis-(acrylamide)-co-poly(ethylene glycol) methyl ether methacrylate-co-N,N'-bis(acryloyl)-cystamine) (PMAA(S-S)) hollow microspheres following a two-stage distillation precipitation polymerization procedure. Magnetic and silver nanocrystals were chemically grown on the surface of the hollow polymer microspheres, resulting in a composite system with, interesting properties. We evaluated the performance of the composite hollow microspheres as magnetic hyperthermia mediators and their surface-enhanced Raman spectroscopy activity. Assessment of Daunorubicin-loaded PMAA(S-S) hollow microspheres performance as effective drug carriers was carried out through drug release experiments upon application of different pH and reducing conditions. pH and redox responsiveness as well as basic mechanisms of release profiles are discussed. Furthermore, in vitro cytotoxicity of empty and drug-loaded PMAA(S-S) hollow microspheres against MCF-7 cancer cells was investigated in order to evaluate their performance as drug carriers.