ИСТИНА

Silicon nanoparticles (SiNPs) are actively used in biophotonics owing to their low level of toxicity, high biocompatibility and biodegradability. Usually, the SiNPs produced by mechanical grinding of porous silicon are effectively applied as photoluminescent markers and photosensitizers. However, the milling technique has limitations to fabricate the particles with a size smaller than 100 nm, which is necessary for more efficient employment in biomedical applications. We suggest employing the pulsed laser ablation in liquids (PLAL) technique to form the small and chemically pure SiNPs to achieve the required characteristics. The pico- and femtosecond laser radiation was used to form the SiNPs via PLAL from crystalline and porous silicon targets. In our experiments the SiNPs fabricated in ethanol and liquid nitrogen demonstrate efficient photoluminescence (PL) with emission maxima in the range of 700 – 800 nm and typical sizes from 2 to 60 nm, which is appropriate for biomedical in vivo applications. The spectrophotometry measurements of suspensions of the ablated SiNPs in water and ethanol revealed effective light scattering. Optical coherence tomography (OCT) imaging of the suspensions drops administered on agar gel surfaces indicated high efficiency of the SiNPs as contrast agents providing the contrast up to 30 dB. The penetration of the SiNPs into a rabbit ear skin followed by light irradiation revealed a pronounced tissue reaction confirming potential of the particles as photosensitizers. Thus, the perspectives of the SiNPs formed via PLAL in optical imaging and photodynamic therapy are demonstrated.