Cytotoxicity of Selenium Nanoparticles Synthesized with the Artificial W8-C3 Metal-Binding Tumor-Targeting Protein

The pW8-3C construct encoding the artificial tumor-targeting protein W8-3C with the addition of three residues of free Cys at the C terminus has been created and described for the first time. Using purified W8-3C protein, dispersions of nanoparticles 75.24 nm in diameter at a polydispersity index (Pdi) of 0.064 and Se content of 1.566 μg/mL were obtained and characterized for the first time. The dispersions remained stable during storage for 6 months at +4°C. For comparison, the maximum Se content in the nanoparticle dispersion obtained in the presence of W8-3C protein and Pluronic F-127 was 399 μg/mL. The cytotoxic activity of the obtained nanoparticles was studied on HeLa (cervical carcinoma), U87MG (glioma), MCF7 (breast carcinoma), and HCT116 (colon carcinoma) human tumor cell lines and compared with that on the diploid human fibroblast line WI-38 in vitro. It was shown that the IC₅₀ of Se nanoparticles obtained using the W8-3C protein for tumor lines ranged from 5.25 to 8.37 μg/mL, while the IC₅₀ for normal fibroblasts was 14.3 μg/mL (difference in values by a factor of 1.7–2.7 times).