Персона: Самохвалов, Павел Сергеевич
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Инженерно-физический институт биомедицины
Цель ИФИБ и стратегия развития – это подготовка высококвалифицированных кадров на базе передовых исследований и разработок новых перспективных методов и материалов в области инженерно-физической биомедицины. Занятие лидерских позиций в биомедицинских технологиях XXI века и внедрение их в образовательный процесс, что отвечает решению практикоориентированной задачи мирового уровня – диагностике и терапии на клеточном уровне социально-значимых заболеваний человека.
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- ПубликацияОткрытый доступУстройство для сбора солнечного излучения(Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский ядерный университет "МИФИ" (НИЯУ МИФИ), 2021-10-21) Соколов, П. М.; Самохвалов, П. С.; Ракович, Ю. П.; Самохвалов, Павел Сергеевич; Соколов, Павел Михайлович
- ПубликацияОткрытый доступSelection of the Optimal Chromatography Medium for Purification of Quantum Dots and Their Bioconjugates(2020) Grokhovsky, S.; Laronze-Cochard, M.; Sapi, J.; Nabiev, I.; Linkov, P.; Samokhvalov, P.; Самохвалов, Павел Сергеевич© 2020 ACS-AIP. All rights reserved.Photoluminescent quantum dots (QDs), due to their unique optical properties and capacity for conjugation with biomolecules, are widely used in biomedicine. However, numerous byproducts of bioconjugation may seriously influence the interaction of these nanoprobes and their targets. The use of size exclusion chromatography (SEC) for the separation of QDs and byproducts of bioconjugation is rather challenging because of the difference in the chemical and physical nature of nanoparticles and biomolecules, which makes the choice of stationary phases for SEC a complicated task. Here we propose a detailed protocol for SEC purification of water-soluble CdSe/ZnS QDs and QD conjugates using Sephadex resins with different porosities and investigate the efficiency of SEC purification of these materials as exemplified by poly(ethylene glycol) derivatives serving as QD-stabilizing ligands, as well as two types of small biomolecules, bis-netropsin and 4,5,9-trisubstituted acridine. We demonstrate that even multiple SEC cycles using the popular prepacked Sephadex G25 columns do not provide efficient purification of QDs, whereas Sephadex G100 and G200 are much more efficient after a single SEC run because of the optimal peak resolution and preservation of the colloidal stability of QDs. Our results show that the use of less common chromatographic media in the group of Sephadex resins allows efficient purification of QD bioconjugates from contaminants for their subsequent use in bioimaging or diagnostics. The proposed SEC protocol can be adapted for purification of not only CdSe-based QDs but also other types of water-soluble nanocrystals with similar sizes and surface properties.
- ПубликацияТолько метаданныеEffect of Spectral Overlap and Separation Distance on Exciton and Biexciton Quantum Yields and Radiative and Nonradiative Recombination Rates in Quantum Dots Near Plasmon Nanoparticles(2020) Krivenkov, V.; Dyagileva, D.; Samokhvalov, P.; Nabiev, I.; Rakovich, Y.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimEfficient biexciton (BX) photoluminescence (PL) from quantum dots (QDs) paves the way to the generation of entangled photons and related applications. However, the quantum yield (QY) of BX PL is much lower than that for single excitons (EX) due to efficient Auger-like recombination. In the vicinity of plasmon nanoparticles, the recombination rates of EX and BX may be affected by the Purcell effect, fluorescence quenching, and the excitation rate enhancement. Here, the effect of the plasmon resonance spectral position on the EX and BX PL is experimentally studied in two cases: when the plasmon band overlaps with the excitation wavelength and when it coincides with the QDs PL band. In the first case, the EX and BX excitation efficiencies are significantly increased but the EX QY reduced. As a result, the BX-to-EX QY ratio is higher than 1 at plasmon–exciton systems separations shorter than 40 nm. In the second case, the radiative recombination rates are enhanced by several orders of magnitude, which led to an increase in BX QY over distances of up to 90 nm. Finally, these two effects are obtained in the same hybrid structure, with the resultant increase in both excitation efficiency and QY of BX PL.
- ПубликацияТолько метаданныеWeak Coupling between Light and Matter in Photonic Crystals Based on Porous Silicon Responsible for the Enhancement of Fluorescence of Quantum Dots under Two-Photon Excitation(2020) Kriukova, I. S.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.; Крюкова, Ирина Сергеевна; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2020, Pleiades Publishing, Inc.The development of optical and, in particular, photoluminescent sensors is currently becoming more and more significant because of their universality, selectivity, and high sensitivity ensuring their wide applications in practice. The efficiency of existing photoluminescent sensors can be increased by using photoluminescent nanomaterials and hybrid nanostructures. For biological applications of photoluminescent sensors, it is extremely relevant to excite photoluminescence in the near infrared spectral range, which allows excluding the effect of autofluorescence of biomolecules and ensuring a deeper penetration of radiation into biological tissues. In this work, it has been studied how the spectral and kinetic parameters of photoluminescence change under two-photon excitation of semiconductor quantum dots incorporated into a one-dimensional photonic crystal, a porous silicon microcavity. It has been shown that the formation of a weak coupling between an exciton transition in quantum dots and an eigenmode of the microcavity enhances the photoluminescence of quantum dots. It is important that quantum dots placed in the porous silicon matrix hold a sufficiently large cross section for two-photon absorption, which makes it possible to efficiently excite their exciton states up to saturation without reaching powers leading to the photothermic destruction of the structure of porous silicon and to the disappearance of the weak coupling effect. It has been demonstrated that the radiative recombination rate under the two-photon excitation of the system consisting of quantum dots and the microcavity increases by a factor of 4.3; it has been shown that this increase is due to the Purcell effect. Thus, fabricated microcavities based on 1D porous silicon crystals allow controlling the quantum yield of photoluminescence of quantum dots under two-photon excitation, which opens prospects for the development of new photoluminescent sensors based on quantum dots operating in the near infrared spectral range.
- ПубликацияТолько метаданныеLong-range coupling of individual quantum dots with plasmonic nanoparticles in a thin-film hybrid material(2020) Rakovich, Y. P.; Dyagileva, D. V.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2020 SPIE.Semiconductor quantum dots (QDs) are widely used in photovoltaic and optoelectronic devices due to their unique optical properties. Photoluminescence (PL) properties of QDs can be significantly improved by their electromagnetic coupling with plasmonic nanoparticles (PNPs). The excitation of resonant localized plasmon modes leads to the enhancement of the density of photon states and increase of electromagnetic field near the surface of PNPs, what boosts the acceleration of the exciton radiative decay, known as the Purcell effect. To study the dependence of the degree of acceleration of radiative decay rate (Purcell factor) on the distance between QDs and PNPs, we fabricated thin-film hybrid structures based on CdSe(core)/ZnS/CdS/ZnS(multishell) QDs and silver or gold PNPs with a controllable distance between these components. The change in the radiative decay rate of excitons was calculated from the PL intensities and lifetimes before and after the deposition of PNPs on top of the QD thin film covered by a poly(methyl methacrylate) (PMMA) spacer. For both PNP types, the PL lifetime of underlying QDs decreased, whereas the PL intensity of the latter decreased only slightly for gold PNPs and even increased for silver PNPs. This indicates the acceleration of QDs radiative decay (Purcell effect) mediated by exciton-plasmon interaction. The Purcell factor was higher for silver PNPs than that for gold PNPs, what can be explained by the better spectral overlap between the QDs PL band and silver PNPs absorbance and the absence of interband absorption in silver at the wavelength of QDs PL. The results of this study provide better understanding of the Purcell effects in hybrid materials based on QDs and PNPs.
- ПубликацияТолько метаданныеStrong coupling effects in a plexciton system of gold nanostars and J-aggregates(2022) Melnikau, D.; Sanchez-Iglesias, A.; Grzelczak, M.; Rakovich, Y. P.; Samokhvalov, P.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2021Strong exciton–plasmon interaction enables effective control of the photonic properties of hybrid organic–inorganic nanostructures encompassing light absorption, scattering and luminescence. Whereas the manifestations of light-matter interactions in the absorption and scattering are reasonably well understood their relation to the luminescence as well as luminescence properties themselves in strongly coupled plexcitonic hybrids is still largely underexplored especially for a system with a complex mechanism of hybridisation of states. Here we report on investigation of the interaction between localized and hybridized plasmons in gold nanostars and excitons in J-aggregates under ambient conditions. Our findings demonstrate the quality performance of the formed plexciton system with multiple hybridization channels in terms of the parameters of strong coupling, such as Rabi splitting (230 meV), coupling-strength-to-transition energy ratio (0.07), and cooperativity (2.03). The results of time-resolved experiments elucidate the observed enhanced spontaneous emission rate with regard to the Purcell effect, whose value was estimated from the extinction spectra of the strongly coupled plexciton system.
- ПубликацияОткрытый доступStrong exciton−photon coupling with colloidal quantum dots in a tunable microcavity(2021) Mochalov, K.; Vaskan, I.; Rakovich, Y.; Dovzhenko, D.; Lednev, M.; Samokhvalov, P.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2021 Author(s).Polariton emission from optical cavities integrated with various luminophores has been extensively studied recently due to the wide variety of possible applications in photonics, particularly promising in terms of the fabrication of low-threshold sources of coherent emission. Tunable microcavities allow extensive investigation of the photophysical properties of matter placed inside the cavity by deterministically changing the coupling strength and controllable switching from weak to strong and ultra-strong coupling regimes. Here, we demonstrate room-temperature strong coupling of exciton transitions in CdSe/ZnS/CdS/ZnS colloidal quantum dots with the optical modes of a tunable low-mode-volume microcavity. Strong coupling is evidenced by a large Rabi splitting of the photoluminescence spectra depending on the detuning of the microcavity. A coupling strength of 154 meV has been achieved. High quantum yields, excellent photostability, and scalability of fabrication of quantum dots (QDs) pave the way to practical applications of coupled systems based on colloidal QDs in photonics, optoelectronics, and sensing.
- ПубликацияТолько метаданныеDetermination of the Single-Exciton Two-Photon Absorption Cross Sections of Semiconductor Nanocrystals through the Measurement of Saturation of Their Two-Photon-Excited Photoluminescence(2020) Karaulov, A.; Krivenkov, V.; Samokhvalov, P.; Dyagileva, D.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2020 American Chemical Society.Conventional approaches to the determination of the two-photon absorption cross-section (TPACS) of fluorescent semiconductor nanocrystals, including quantum dots (QDs) and nanoplatelets (NPLs), cannot be applied to samples with unknown concentrations and low optical densities and may be inaccurate in the case of multiexciton nanocrystal excitation. Here, we have studied the two-photon-excited photoluminescence saturation in QD and NPL samples and propose a novel technique for determining of their TPACS from the parameters of this process. The technique allows the measurement of the TPACSs of single exciton states in the samples of unknown concentration, as well as in thin films with ultralow optical densities. The calculated values agreed with the results obtained by conventional methods. The new technique paves new ways to studying small amounts of fluorescent nanocrystals of unknown quantity under two-photon excitation.
- ПубликацияТолько метаданныеEnhanced spontaneous emission from two-photon-pumped quantum dots in a porous silicon microcavity(2020) Dovzhenko, D.; Krivenkov, V.; Kriukova, I.; Samokhvalov, P.; Nabiev, I.; Крюкова, Ирина Сергеевна; Самохвалов, Павел Сергеевич; Набиев, Игорь РуфаиловичPhotoluminescence (PL)-based sensing techniques have been significantly developed in practice due to their key advantages in terms of sensitivity and versatility of the approach. Recently, various nanostructured and hybrid materials have been used to improve the PL quantum yield and the spectral resolution. The near-infrared (NIR) fluorescence excitation has attracted much attention because it offers deep tissue penetration and it avoids the autofluorescence of the biological samples. In our study, we have shown both spectral and temporal PL modifications under two-photon excitation of quantum dots (QDs) placed in one-dimensional porous silicon photonic crystal (PhC) microcavities. We have demonstrated an up-to-4.3-fold Purcell enhancement of the radiative relaxation rate under two-photon excitation. The data show that the use of porous silicon PhC microcavities operating in the weak coupling regime permits the enhancement of the PL quantum yield of QDs under two-photon excitation, thus extending the limits of their biosensing applications in the NIR region of the optical spectrum. (C) 2020 Optical Society of America
- ПубликацияТолько метаданныеPrinciples of Chemical Designing of Styrene-Based Plastic Scintillators Doped with Quantum Dots(2024) Knysh, A.; Kirsanov, M.; Sosnovtsev, V.; Nabiev, I.; Samokhvalov, P.; Кныш, Александр Александрович; Кирсанов, Михаил Алексеевич; Сосновцев, Валерий Витальевич; Набиев, Игорь Руфаилович; Самохвалов, Павел Сергеевич