ИСТИНА

We report on silicon nanoparticles fabrication approach consisting in sequential application of electrochemical etching and pico- and femtosecond laser ablation of silicon in liquids (water, ethanol, and liquid nitrogen). As a result, suspensions of silicon nanoparticles (Si-NPs) with the size of less than 50 nm were formed with a shape close to a spherical one. Si-NPs exhibit effective photoluminescence (PL) with an emission peak within the biotissues transparency window (at 720 nm for laser ablation in ethanol and at 740 nm for liquid nitrogen). Due to the relatively small size, these nanoparticles are promising as PL markers for optical bioimaging. Optical properties of silicon nanoparticle suspensions produced by ablation in water and ethanol were reconstructed from spectrophotometry measurements employing inverse Monte Carlo technique. All the studied samples revealed a monotonous decrease of the absorption coefficient with the wavelength increase in the range of 400 – 1100 nm. Scattering coefficient of the Si-NPs suspensions was demonstrated to exceed absorption coefficient in the entire considered range. The study of the efficacy of the produced suspensions as contrasting agents for bioimaging was performed by optical coherence tomography (OCT) imaging of agar phantoms upon suspensions topical administration. The Si-NPs were demonstrated to sufficient increase the OCT signal level in comparison with the pure agar phantom and were proved to serve as contrasting agents for biological tissues and tissue-like media during optical imaging.