ИСТИНА

Nanoparticles (NPs) of pure silicon (Si) are known to be biocompatible, biodegradable and promising for various biomedical applications as bioimaging, drug delivery, photodynamic therapy and photothermal treatment (hy-perthermia), and ultrasound-assisted (sonodynamic) therapy of cancer. Si NPs can be efficiently heated by radio-frequency radiation to realize a hyperthermia regime for destruction of tumors. Recently, Si NPs and those with iron impurities have been explored as contrast agents (CAs) for MRI. Measurements of the proton magnetization lifetime and MRI experiments with phantoms show maximal CA properties for transversal time mode that is explained by enhanced proton relaxation in water molecules due to the interaction with silicon dangling bonds of Si NPs. Porous Si NPs are explored as containers for positron-emitting radionuclides as 68Ga in high quantities (up to 95%). 68Ga-labeled PSi NPs exhibit high stability in vitro. In vivo studies of the pharmacokinetic proper-ties of PSi NPs with incorporated 68Ga after intra-tumoral administration to animals with experimental cholan-gioma RS-1 show that more than 50% of the labeled PSi NPs were retained by tumor tissue for 5 h. The intrave-nous administration resulted in gradual accumulation of labeled nanoparticles in the tumor. The highest levels of the radioactivity during intravenous administration were observed in the organs of the reticuloendothelial sys-tem. The obtained results show high prospects for creating new porous silicon-based radiopharmaceuticals for the positron emission tomography (PET), as well as novel theranostic agents for the PET-guided treatment of malignant tumors. In vivo and in vivo studies confirm outstanding properties of PSi NPs for mild therapy appli-cations. PSi NPs produced by mechanical grinding of porous silicon were explored as antiviral agents for sup-pression of the infections induced by human immunodeficiency virus (HIV) and respiratory syncytial virus (RSV) in vitro. A suppression of the viral activity was observed for the SiNP concentration, which were signifi-cantly lower than the corresponding cytotoxic concentrations. The observed effect is related to an efficient bind-ing of the viruses with PSi NPs.The obtained results indicate new prospective area of biomedical applications of PSi in both therapy and diagnostics (theranostics) of cancer and inflectional diseases.