Apollo 11lb913 microplate reader

The size and morphology of nanoparticles were examined using a Zeiss Libra 120 Plus TEM operating at 120 kV (Zeiss, Stuttgart, Germany). The DLS method was used to analyze the hydrodynamic size of the synthesized nanoparticles and PEG conjugates. The hydrodynamic diameter and zeta potential measurements were conducted in 1 mM PBS pH 7.4 buffer using a Zetasizer Nano ZS (Malvern Panalytical, Malvern, Worcestershire, UK). The magnetic properties of the obtained nanoparticles were tested using a QD VSM vibrating magnetometer by NanoMagnetics Instruments (Oxford, UK) operating in the range of –2.0 to +2.0 T. Measurements were carried out in the temperature range from 100–300 K with an accuracy of 0.01 K. The SAR values were determined using MaNIaC Controller software supplied with D5 series equipment. The MTS assay absorbance values were evaluated at 490 nm via an Apollo 11LB913 microplate reader (Berthold, Bad Wildbad, Germany). The radioactivity of samples was measured using Wizard^® 2 automatic gamma counter (Perkin Elmer, Waltham, MA, USA).

To assess cell metabolic activity, the MTS assay was used. The cytotoxicity of the synthesized BaFeNPs, BaFe–CEPA–trastuzumab bioconjugate, [²²³Ra]BaFe–CEPA–trastuzumab radiobioconjugate, [²²³Ra]BaFe–CEPA nanoparticles and ²²³Ra radionuclide was evaluated on the SKOV-3 cell line. Cells were seeded in 96-well microplates (TPP, Switzerland) at a density of 2 × 10³ cells per well. Afterwards, cells were washed with cold PBS and treated (in triplicates) with increasing concentrations of the radiocompounds (0.1–50.0 kBq/mL) and non-radioactive barium ferrite (0.78–400.00 µg/mL) suspended in cell culture medium at a volume of 100 µL per well. The SKOV-3 cells were incubated with compounds for 2 h at 37 °C. Afterwards, cells were washed twice with PBS and subsequently incubated in the presence of fresh cell culture medium at 37 °C for 24 and 48 h. After each time of incubation, 20 μL of CellTiter 96^® AQueous One Solution Reagent (Promega, Mannheim, Germany) were added to each well and incubated for another 2 h at 37 °C. Next, the absorbance of the samples was measured at 490 nm using the Apollo 11LB913 microplate reader (Berthold, Bad Wildbad, Germany). The results are presented as a percentage of cell viability in comparison to the control represented by cells cultured in medium only. The IC₅₀ in kBq/mL was calculated by analyzing viability curves with GraphPad Prism (7.0).

Cytotoxicity studies were performed by MTS colorimetric assay for increasing the concentration of [Ho]Fe₃O₄@Au, [Ho]Fe₃O₄@Au-PEG, [Ho]Fe₃O₄@Au-Tmab (0.78–400 µg/mL) and c.a. ¹⁶⁶HoCl₃∙(0.05–30 MBq/mL). SKOV3 cells were seeded 24 h before the experiment in 96-well plates at a density of 2.0 × 10³ per well. Then the cells were washed with PBS and treated with increasing concentrations of the studied compounds, to a volume of 100 µL. Seeded cells were incubated with compounds for 18 h, washed twice with 100 µL of PBS, and incubated for another 24, 48, and 72h at 37 °C. Next, an MTS assay was added to each well, and plates were incubated for an additional 2 h at 37 °C in the dark. Lastly, the absorbance was measured at 490 nm using the Apollo 11LB913 microplate reader, Berthold (Bad Wildbad, Germany). The results are presented as cell viability (%) in comparison to the control not treated with the studied compounds.