Development of Nile red-functionalized magnetic silica nanoparticles for cobalt ion sensing and entrapping

A new type of hybrid nanoparticles (NPs) with combined magnetic and fluorescent properties in single particle was developed by incorporating magnetic silica NPs with highly fluorescent Nile red dyes. These NPs clearly exhibit Co2+ ion entrapping ability in aqueous milieu and Co2+-induced fluorescence enhancement features with high selectivity owing to the Co2+-triggered inhibition on the photoinduced electron transfer progress in the efficient fluorophore (Nile red derivative). Moreover, these dual-functional NPs display superparamagnetic features and the motion of these fluorescent NPs can be induced by the application of an external magnetic field, enabling a facile separation/removal of toxic Co2+ ion from the aqueous milieu and real-time monitoring via fluorescence measurements.