Study on core–shell–shell structured nanoparticles with magnetic and luminescent features: Construction, characterization and oxygen-sensing behavior

In this paper, we construct core–shell–shell structured nanoparticles, where magnetic Fe3O4 nanoparticles are used as the inner core, mesoporous silica functionalized with phosphorescent Ru(II) complex is used as the outer shell, and the middle shell which is composed of amorphous silica is introduced to minimize the negative effect from the inner core on the sensing probes. The obtained magnetic–luminescent composite nanoparticles are characterized by XRD analysis, IR spectrum, electron microscopy, fluorescence microscopy, thermogravimetric analysis and nitrogen adsorption and desorption, confirming the core–shell–shell structure. The magnetic and photophysical properties of the composite nanoparticles are investigated in detail. Data suggest that the nanoparticles show a smaller saturation magnetization value compared with that of Fe3O4 nanoparticles. The composite namoparticles are red-emitting ones, and the emission is sensitive towards oxygen concentration variations with sensitivity of 4.1 and response time of 7 s.