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DNA aptamers have many benefits for cell imaging, such as high affinity and specificity, easiness of chemical functionalization, and low cost of production. Among known aptamers, Sgc8-aptamer was selected against acute lymphoblastic leukemia cells with a dissociation constant in a nanomolar range. The aptamer was previously used for the covalent coupling with fluorescent and magnetic nanoparticles, as well as for the fabrication of aptamer-based biosensors. Among commonly used fluorescent tags, lanthanide nanoparticles offer stable luminescence with narrow, well-resolved emission peaks and the absence of photoblinking. In other words, lanthanide nanoparticles could serve as luminescence reporters and be used in biosensing. In our study, we conjugated amino- and carboxyl-modified silica-coated terbium (III) thiacalix[4]arenesulfonate luminescent nanoparticles with Sgc8-aptamer and showed the ability of the aptamer-conjugated nanoparticles to detect leukemia cells using fluorescence microscopy. In addition, we conducted a cell viability assay and confirmed that the nanoparticles do not induce spontaneous cell apoptosis or necrosis and could be potentially used for bioimaging applications.

The present work introduces composite luminescent nanoparticles (Ag 0 -Tb 3+ -SNs), where ultra-small nanosilver (4 ± 2 nm) is deposited onto amino-modified silica nanoparticles (35±6 nm) doped by green luminescent Tb(III) complexes. Ag 0 -Tb 3+ -SNs are able to image cancer (Hep-2) cells in confocal microscopy measurements due to efficient cell internalization, which is confirmed by TEM images of the Hep-2 cells exposed by Ag 0 -Tb 3+ -SNs. Comparative analysis of the cytotoxicity of normal fibroblasts (DK-4) and cancer cells (Hep-2) incubated with various concentrations of Ag 0 -Tb 3+ -SNs revealed the concentration range where the toxic effect on the cancer cells is significant, while it is insignificant towards the nonmalignant fibroblasts cells. The obtained results reveal Ag 0 -Tb 3+ -SNs as good cellular contrast agent able to induce the cancer cells death, which makes them promising theranostic in cancer diagnostics and therapy., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The present work introduces deliberate synthesis of Gd(III)-doped silica nanoparticles with high relaxivity at magnetic field strengths below 1.5T. Modified microemulsion water-in-oil procedure was used in order to achieve superficial localization of Gd(III) complexes within 40-55nm sized silica spheres. The relaxivities of the prepared nanoparticles were measured at 0.47, 1.41 and 1.5T with the use of both NMR analyzer and whole body NMR scanner. Longitudinal relaxivities of the obtained silica nanoparticles reveal significant dependence on the confinement mode, changing from 4.1 to 49.6mM -1 s -1 at 0.47T when the localization of Gd(III) complexes changes from core to superficial zones of the silica spheres. The results highlight predominant contribution of the complexes located close to silica/water interface to the relaxivity of the nanoparticles. Low effect of blood proteins on the relaxivity in the aqueous colloids of the nanoparticles was exemplified by serum bovine albumin. T 1 - weighted MRI data indicate that the nanoparticles provide strong positive contrast at 1.5T, which along with low cytotoxicity effect make a good basis for their application as contrast agents., (Copyright © 2016 Elsevier B.V. All rights reserved.)