ИСТИНА

In our work we report on efficient techniques for formation of silicon nanoparticles (Si-NPs) via pulsed laser ablation and fragmentation of porous silicon films, silicon nanowires arrays and mechanically grinded silicon microparticles. Laser ablation in liquids (water and ethanol) allows to avoid undesirable chemical impurities unlike chemical fabrication techniques. Preliminary nano- and microstructuring of crystalline silicon provides reduced ablation threshold and, therefore, high yield of ablation products. Variation of the silicon-based targets, buffer liquids, and laser impact parameters allows to fabricate Si-NPs with mean sizes from 25 to 400 nm demonstrating the high degree of crystallinity. Spectrophotometry measurements of the Si-NPs suspensions revealed their effective scattering in the spectral range of 400 – 1000 nm which was explained in the frames of the Mie theory. Optical coherence tomography imaging of the suspensions drops administered on agar gel surfaces indicated high efficiency of the Si-NPs as contrast agents providing the image contrast up to 30 dB. Based on the measured scattering and absorption spectra of the Si-NPs suspensions, heating of tumor tissue with embedded nanoparticles was numerically modelled to evaluate their potential in tumor photohyperthermia. The obtained results allow to conclude that the Si-NPs fabricated via laser ablation and fragmentation of preliminary nano- and microstructured silicon are promising in both contrasting in optical bioimaging and in enhancing photohyperthermia of malignant tumors.