ИСТИНА

Silicon nanoparticles (SiNPs) are successfully used in various biomedical applications due to their low toxicity and biodegradability. In this paper we study the possibility of employment of laser-ablated SiNPs in biophotonics. The particles are formed by femtosecond (1250 nm, 150 fs) and picosecond (1064 nm, 34 ps) laser ablation of monocrystalline and porous silicon targets in various liquids: water, ethanol, liquid nitrogen, and aqueous ethanol solution with silver nitrate. In the latter case, it is possible to decorate the SiNPs surface with silver nanoparticles (Si/Ag). As a result of the ablation, SiNPs suspensions were fabricated with the nanoparticles mean size varying from 25 to 120 nm depending on the parameters of laser pulses (energy, duration, and number), the targets used, and the buffer liquids. An analysis of the measured values of the scattering and absorption coefficients of the prepared SiNPs suspensions showed that such nanosystems have high potential as contrast agents in optical coherence tomography. This assumption was confirmed by experiments on contrasting structural inhomogeneities of agar gel with the embedded SiNPs. A numerical experiment of a photohyperthermia process with the SiNPs embedded into a human subcutaneous basal cell carcinoma showed that it is possible to provide hyperthermia of the entire tumor without significant overheating the surrounding healthy tissues. A real experiment on heating was carried out with a phantom simulating the optical properties of human skin (agar gel with lipofundin and red ink) and confirmed that the adminisration of the SiNPs on the phantom increases its heating under equivalent irradiation conditions compared with the phantom without nanoparticles. Additionally, the decorated Si/Ag nanoparticles are of interest for further research as agents for photohyperthermia, since the silver inclusions may increase heating without increasing the mass concentration of the agents. In vivo monitoring of the reaction of laboratory mice after administration of the SiNPs was carried out using the “Open field” test, which makes it possible to estimate the general (locomotor) and exploratory animal activities. Low toxicity of the SiNPs was shown for oral and topical administration, however, an increase in the stress level in the experimental groups relative to the control ones was revealed. Thus, the biocompatible SiNPs formed by laser ablation in liquids are of undoubted interest for solving problems of biological tissues theranostics.