2019, Perepukhov, A. M., Zvereva, E. A., Koshelev, A. V., Maximychev, A. V., Kargina, Y. V., Kharin, A. Y., Zinovyev, S. V., Alykova, A. F., Pirogov, Y. A., Timoshenko, V. Y., Тимошенко, Виктор Юрьевич

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Silicon (Si) nanoparticles (NPs) with small (10 −3 –10 −1 at%) content of iron oxide (Fe 2 O 3 ) are prepared by plasma-assisted ablative synthesis. Powders of the prepared Si-iron oxide (SIO) NPs are investigated by means of the transmission electron microscopy, Raman spectroscopy, electron paramagnetic resonance, and magnetic susceptibility measurements. Aqueous suspensions of the NPs are studied by using dynamic light scattering and nuclear magnetic resonance technique. The longitudinal and transverse relaxation times of protons in aqueous suspensions of the NPs are found to be dependent on the iron content. The stronger decrease of the proton relaxation is detected for the samples with higher iron content. Magnetic resonance imaging (MRI) experiments show that SIO NPs have properties of the MRI contrast agent and it is confirmed by in vivo experiments with cancer tumor. Aqueous suspensions of SIO NPs are explored as sensitizers of electromagnetic radio frequency hyperthermia and the highest heating rate is observed for the NPs with smaller hydrodynamic size (≈50 nm). The obtained results indicate possible ways for applications of SIO NPs in the MRI diagnostics and mild therapy of cancer.

2022, Fronya, A. A., Antonenko, S. V., Karpov, N. V., Pokryshkin, N. S., Eremina, A. S., Kharin, A. Y., Dombrovska, Y. I., Garmash, A. A., Kargin, N. I., Klimentov, S. M., Timoshenko, V. Y., Фроня, Анастасия Андреевна, Антоненко, Сергей Васильевич, Еремина, Анна Сергеевна, Гармаш, Александр Александрович, Каргин, Николай Иванович, Климентов, Сергей Михайлович, Тимошенко, Виктор Юрьевич

Due to particular physico-chemical characteristics and prominent optical properties, nanostructured germanium (Ge) appears as a promising material for biomedical applications, but its use in biological systems has been limited so far due to the difficulty of preparation of Ge nanostructures in a pure, uncontaminated state. Here, we explored the fabrication of Ge nanoparticles (NPs) using methods of pulsed laser ablation in ambient gas (He or He-N2 mixtures) maintained at low residual pressures (1-5 Torr). We show that the ablated material can be deposited on a substrate (silicon wafer in our case) to form a nanostructured thin film, which can then be ground in ethanol by ultrasound to form a stable suspension of Ge NPs. It was found that these formed NPs have a wide size dispersion, with sizes between a few nm and hundreds of nm, while a subsequent centrifugation step renders possible the selection of one or another NP size fraction. Structural characterization of NPs showed that they are composed of aggregations of Ge crystals, covered by an oxide shell. Solutions of the prepared NPs exhibited largely dominating photoluminescence (PL) around 450 nm, attributed to defects in the germanium oxide shell, while a separated fraction of relatively small (5-10 nm) NPs exhibited a red-shifted PL band around 725 nm under 633 nm excitation, which could be attributed to quantum confinement effects. It was also found that the formed NPs exhibit high absorption in the visible and near-IR spectral ranges and can be strongly heated under photoexcitation in the region of relative tissue transparency, which opens access to phototherapy functionality. Combining imaging and therapy functionalities in the biological transparency window, laser-synthesized Ge NPs present a novel promising object for cancer theranostics.

2019, Assilbayeva, R. B., Kharin, A. Y., Kargina, Y. V., Timoshenko, V. Y., Тимошенко, Виктор Юрьевич

© Published under licence by IOP Publishing Ltd. Silicon nanoparticles and nanowires prepared by using different methods were investigated by means of x-ray diffraction (XRD) technique. Broadening of the XRD lines of crystalline Si lattice allows us to estimate the mean size of nanoparticles. Silicon nanoparticles stored in aqueous suspensions for several days were found to decrease their sizes due to dissolution process. The kinetics of dissolution for different kinds of nanoparticles were found to be different. It was also shown that the most unstable nanoparticles (microporous silicon ones) could be protected from dissolution via interaction with the polysaccharide molecules (dextrane) into the solution.

2020, Muratov, A. V., Fronya, A. A., Antonenko, S. V., Kharin, A. Y., Aleshchenko, Y. A., Derzhavin, S. I., Karpov, N. V., Dombrovska, Y. I., Garmash, A. A., Kargin, N. I., Klimentov, S. M., Timoshenko, V. Y., Kabashin, A. V., Фроня, Анастасия Андреевна, Антоненко, Сергей Васильевич, Алещенко, Юрий Анатольевич, Гармаш, Александр Александрович, Каргин, Николай Иванович, Климентов, Сергей Михайлович, Тимошенко, Виктор Юрьевич, Кабашин, Андрей Викторович

Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5-5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the "red - near infrared" (maximum at 760 nm) and "green" (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense "green-yellow" PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

2019, Rogov, A., Ryabchikov, Y. V., Geloen, A., Tishchenko, I., Kharin, A. Y., Lysenko, V., Zavestovskaya, I. N., Kabashin, A. V., Timoshenko, V. Y., Завестовская, Ирина Николаевна, Кабашин, Андрей Викторович, Тимошенко, Виктор Юрьевич

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Presenting a safe alternative to conventional compound quantum dots and other functional nanostructures, nanosilicon can offer a series of breakthrough hyperthermia-based therapies under near-infrared, radiofrequency, ultrasound, etc., excitation, but the size range to sensitize these therapies is typically too large (>10 nm) to enable efficient imaging functionality based on photoluminescence properties of quantum-confined excitonic states. Here, it is shown that large Si nanoparticles (NPs) are capable of providing two-photon excited luminescence (TPEL) and second harmonic generation (SHG) responses, much exceeding that of smaller Si NPs, which promises their use as probes for bi-modal nonlinear optical bioimaging. It is finally demonstrated that the combination of TPEL and SHG channels makes possible efficient tracing of both separated Si NPs and their aggregations in different cell compartments, while the resolution of such an approach is enough to obtain 3D images. The obtained bi-modal contrast provides lacking imaging functionality for large Si NPs and promises the development of novel cancer theranostic modalities on their basis.

2022, Eremina, A. S., Gavrilin, I. M., Pokryshkin, N. S., Kharin, A. Y., Kharin, A.Y., Syuy, A. V., Volkov, V. S., Yakunin, V. G., Bubenov, S. S., Dorofeev, S. G., Gavrilov, S. A., Еремина, Анна Сергеевна, Тимошенко, Виктор Юрьевич

Layers of germanium (Ge) nanowires (NWs) on titanium foils were grown by metal-assisted electrochemical reduction of germanium oxide in aqueous electrolytes based on germanium oxide without and with addition of sodium silicate. Structural properties and composition of Ge NWs were studied by means of the scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. When sodium silicate was added to the electrolyte, Ge NWs consisted of 1–2 at.% of silicon (Si) and exhibited smaller mean diameter and improved crystallinity. Additionally, samples of Ge NW films were prepared by ultrasonic removal of Ge NWs from titanium foils followed with redeposition on corundum substrates with platinum electrodes. The electrical conductivity of Ge NW films was studied at different temperatures from 25 to 300 °C and an effect of the silicon impurity on the thermally activated electrical conductivity was revealed. Furthermore, the electrical conductivity of Ge NW films on corundum substrates exhibited a strong sensor response on the presence of saturated vapors of different liquids (water, acetone, ethanol, and isopropanol) in air and the response was dependent on the presence of Si impurities in the nanowires. The results obtained indicate the possibility of controlling the structure and electrical properties of Ge NWs by introducing silicate additives during their formation, which is of interest for applications in printed electronics and molecular sensorics. © 2022 by the authors.

2021, Kharin, A. Y., Grigoryeva, M. S., Zavestovskaya, I. N., Timoshenko, V. Y., Григорьева, Мария Сергеевна, Завестовская, Ирина Николаевна, Тимошенко, Виктор Юрьевич

Ablation of a porous silicon target under irradiation with ultrashort laser pulse is simulated by means of the molecular dynamics approach. The number of ablated atoms is calculated for targets with different porosity under irradiation with wavelengths in ultraviolet (UV) and visible spectral ranges, which correspond to stronger and weaker absorption coefficient, respectively. An increase of the porosity to 80% leads to 1.5-3 times decrease of the ablation threshold compared to the bulk silicon, while a decrease of pores size from 2.5 to 1.2 nm leads to the stronger ablation threshold drop and the effect is stronger for the UV irradiation. The results are useful for laser processing of silicon-based targets and nanofabrication.

2021, Grigoriev, A. A., Grigoryeva, M. S., Kargina, Y. V., Kharin, A. Y., Zavestovskaya, I. N., Kanavin, A. P., Timoshenko, V. Y., Григорьев, Андрей Андреевич, Григорьева, Мария Сергеевна, Завестовская, Ирина Николаевна, Канавин, Андрей Павлович, Тимошенко, Виктор Юрьевич

© 2021, Allerton Press, Inc.Abstract: The heat release during electromagnetic high-frequency (HF) heating of solid-state nanoparticle (NP) suspensions in an electrolyte with physiological solution conductivity is studied. It is shown that heating of a colloidal NP solution in an electrolyte should be calculated taken into account the contribution of an electric double layer formed near the NP surface, and the heating efficiency is controlled by the NP conductivity and the ratio of the frequency of radio-frequency radiation and the electrolyte conductivity. The optimal conductivity of silicon-based NPs for hyperthermia is determined as a function of the HF radiation frequency.

2022, Petukhov, D. I., Eremina, A. S., Kargina, Y. V., Kharin, A. Y., Timoshenko, V. Y., Еремина, Анна Сергеевна, Тимошенко, Виктор Юрьевич

© 2021We propose a one-step procedure to stabilize mesoporous silicon nanoparticles in aqueous solutions by polyethylene glycol (PEG) coating during grinding in a planetary ball mill. The milling is done in aqueous medium that allows us to directly obtain the aqueous suspension of PEGylated nanoparticles. The prepared nanoparticles are investigated by means of the scanning electron microscopy, energy dispersive X-ray spectroscopy, low-temperature nitrogen sorption, dynamic light scattering, Fourier transform infrared spectroscopy, Raman and photoluminescence spectroscopy, which reveal the nanoparticle size of 50–100 nm, preservation of the nanocrystallinity and mesopores. The PEGylated nanoparticles are found to be stable in aqueous solution for at least 24 h. The proposed PEGylation method can be used to control the physical properties and stability of mesoporous silicon nanoparticles for biomedical applications.

2020, Oleshchenko, V. A., Karpukhina, O. V., Bezotosnyi, V. V., Kharin, A. Y., Alykova, A. F., Karpov, N. V., Popov, A. A., Klimentov, S. M., Zavestovskaya, I. N., Kabashin, A. V., Timoshenko, V. Y., Попов, Антон Александрович, Климентов, Сергей Михайлович, Завестовская, Ирина Николаевна, Кабашин, Андрей Викторович, Тимошенко, Виктор Юрьевич

© 2020 Elsevier B.V.Silicon (Si) nanoparticles (NPs) synthesized by methods of laser ablation in water are explored as sensitizers of photothermal therapy under a laser excitation in the window of relative tissue transparency. Based on theoretical calculations and experimental data, it is shown that the NPs can be heated up to temperatures above 42–50 °C by laser diode irradiation at 808 nm in continuous wave (CW) and quasi-continuous wave (QCW) regimes. Profiting from the laser-induced heating, a high efficiency Si-NPs as sensitizers of the hyperthermia of cells in Paramecium Caudatum model is demonstrated. The QCW regime is found to be more efficient, leading to complete cell destruction even under relatively mild laser irradiation conditions. The obtained data evidence a great potential in using laser-ablated Si-NPs as sensitizers of photohyperthermia in antibacterial or cancer therapy applications.