Cellular imaging by green luminescence of Tb(III)-doped aminomodified silica nanoparticles

•Low leakage of luminescent complex from silica nanoparticles results in their low cytotoxicity.•The nanoparticles size variation from 35 to 20 nm affects their aggregation and luminescence.•Amino-decoration of silica surface of the nanoparticles enhances their cell internalization.•Size-effect on mechanisms of cell internalization of the nanoparticles is observed.•Cytotoxicity of the nanoparticles correlates with their cellular uptake behavior.

The work introduces Tb(III)-centered luminescence of amino-modified silica nanoparticles doped with Tb(III) complexes for cellular imaging. For these purposes water-in-oil procedure was optimized for synthesis of 20 and 35 nm luminescent nanoparticles with amino-groups embedded on the surface. The obtained results indicate an impact of the nanoparticle size in decoration, aggregation behavior and luminescent properties of the nanoparticles in protein-based buffer solutions. Formation of a protein-based corona on the nanoparticles surface was revealed through the effect of the nanoparticles on helical superstructure of BSA. This effect is evident from CD spectral data, while no any size impact on the adsorption of BSA onto aminomodified silica surface was observed. Cellular uptake of the nanoparticles studied by confocal and TEM microscopy methods indicates greater cellular uptake for the smaller nanoparticles. Cytotoxicity of the nanoparticles was found to agree well with their cellular uptake behavior, which in turn was found to be greater for the smaller nanoparticles.

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