Luminescent silicate core–shell nanoparticles: Synthesis, functionalization, optical, and structural properties

Abstract

SiO 2/Zn 2SiO 4:Mn 2+ core–shell nanoparticles with mean diameters in the range of 55–220 nm were prepared by a modified Pechini sol–gel method followed by lyophilization and annealing at temperatures of 800–1100 °C. The as-synthesized nanoparticles were characterized by transmission electron microscopy, X-ray diffraction analysis, and photoluminescence spectroscopy. The results demonstrate that the crystal structure of the shell and the optical properties can be tuned by the annealing temperature and a variation of the concentration of doping ions. Under UV excitation, the samples emit green luminescence with its maximum at 525 nm, typical for the Mn 2+ ions in α-Zn 2SiO 4. The resulting nanoparticles were successfully modified with amine and carboxyl functions with respect to a later attachment of biological moieties.