Poly(<i>N</i>-isopropylacrylamide)-Coated Luminescent/Magnetic Silica Microspheres:  Preparation, Characterization, and Biomedical Applications

Abstract

Smart microstructures based on organic/inorganic hybrids were rationally designed to develop applications in the novel interdisciplinary research field “nanobioscience”. These multifunctional microspheres, combining several advances of photoluminescence and magnetic and temperature responses into one single entity, have been prepared via three steps. The first step involved magnetite nanoparticles (Fe 3 O 4 ) homogeneously incorporated into silica spheres using the modified Stöber method. Second, metal ions (Cd 2+ ) were utilized to precipitate the differently sized thiol-capped CdTe nanocrystals onto the Fe 3 O 4 -dotted silica surface with negative charges, and then a thin silica shell was coated on them in favor of formation of a robust platform provided for anticorrosion of quantum dots. Third, the modified silica-coated Fe 3 O 4 @SiO 2 @CdTe microspheres were covered with the outer shell of thermosensitive poly( N -isopropylacrylamide) via template polymerization. These hybrid microspheres are desired as carriers for diagnostics, circulating drug-delivery systems, and treating cancer at its earliest stages.