ИСТИНА

Nowadays silicon nanoparticles (Si-NPs) produced by mechanical grinding of porous silicon are efficiently used in bioimaging and therapeutic applications [1,2]. We suggest employing an alternative technique consisting in pulsed laser ablation in liquids (PLAL) to fabricate small and chemically pure Si-NPs for biomedical applications. Pico- and femtosecond laser radiation was used to form the Si-NPs via PLAL from porous silicon targets. In our experiments the Si-NPs are fabricated in water, ethanol and liquid nitrogen and characterized by sizes smaller than 100 nm. Raman spectroscopy revealed a presence of the lines for crystalline (520 cm-1) and amorphous (480 cm-1) silicon phases (Fig.1a). An analysis of the ratio of these lines integral intensities indicated that the volume fraction of the crystalline particles is higher than 87% for all types of the studied samples. Spectrophotometry measurements of the ablated Si-NPs suspensions revealed that scattering coefficient value reaches up to 0.3 mm-1 in the spectral range of 400 – 1000 nm (Fig.1b as example). 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 contrast up to 30 dB. Thus, the perspectives of the Si-NPs formed via PLAL in optical imaging are demonstrated. This work was supported by the Russian Science Foundation (project № 19-12-00192). References [1] O.I. Ksenofontova, A.V. Vasin, V.V. Egorov, et al., Tech. Phys. 59, 66 – 77 (2014). [2] V. Stojanoviс, F. Cunin, J.O. Durand, et al., J. Mater. Chem. B 4, 7050 – 7059 (2016).