ИСТИНА

Over the last decade, there is a constantly growing interest in using nanoparticles (NPs) for biomedical applications [1]. Silicon (Si) NPs have attracted attention for biomedical applications due to their low toxicity and biodegradability. For example, Si-NPs have been shown to be excreted from the mice body through renal clearance within few weeks [2]. Iron (Fe) based NPs were actively studied because of their excellent physical properties such as high saturation magnetization and high magnetic susceptibility. They can be used for numerous biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, magnetic hyperthermia, drug delivery, etc. [3]. In this work, we have synthesized composite Silicon-Iron (Si-Fe) NPs by laser ablation and investigated the obtained NPs for biomedical applications as potential contrast agents in MRI. Si-Fe NPs were synthesized by femtosecond laser ablation of Si and Fe-silicide mixed target in a quartz vessel filled with distilled water. The laser ablation was done by femtosecond Yb: KGW laser (Avesta, Teta 10, Russia) with 1030 nm wavelength, pulse repetition rate from 1 to 100 kHz and pulse energy up 100 μJ for 30 minutes. NPs were investigated by means of the transmission and scanning electron microscopies (TEM, SEM), X-ray fluorescence (XRF), X-ray diffraction, dynamic light scattering (DLS) and NMR Relaxometry. 146 The 6th International Symposium and Schools for Young Scientists on Physics, Engineering and Technologies for Biomedicine TEM, SEM images and DLS data demonstrate that the prepared NPs are mostly spherical with mean diameters ranging from 20 to 220 nm. According to the XRF analysis the prepared NPs contain from 10 to 25 at. % of Fe in silicide and oxide forms. Figure 1 shows typical transients of the longitudinal and transverse proton magnetization in suspensions of SiFe NPs with 25 at. % of Fe. The magnetization transients reveal strong shortening of the relaxation times. The relaxivity values for the longitudinal and transverse proton magnetization are r1= 0.9 Lg-1s-1 and r2 = 16.4 Lg1 Fig. 1. Transients of the longitudinal and transverse proton magnetization in pure water (black lines) and in aqueous suspensions of SiFe NPs (red lines) s-1, respectively. The obtained high relaxivities of the prepared NPs demonstrate their potential for applications as contrast agents in MRI diagnostics of cancer. [1] H.A. Khan, M.K. Sakharkar, A. Nayak, U. Kishore, A. Khan, Nanoparticles for biomedical applications: An overview, Nanobiomat., pp. 357-384, 2018. [2] J.H. Park, L. Gu, G. von Maltzahn, E. Ruoslahti, S.N. Bhatia, M.J. Sailor, Biodegradable luminescent porous silicon nanoparticles for in vivo applications, Nat Mater, vol. 8, pp. 331-336, 2009. [3] M. Mahdavi, M.B. Ahmad, M.J. Haron, F. Namvar, B. Nadi, M.Z.A. Rahman, J. Amin, Synthesis, surface modification and characterization of biocompatible magnetic iron oxide nanoparticles for biomedical applications, Molecules, vol. 18, no. 7, pp. 7533-48, 2013. 147