Maksimchuk P. Redox-activity mechanisms of orthovanadate nanocrystals of rare-earth elements REVO4:Eu3+ (RE = Gd, Y, La)

Українська версія

Thesis for the degree of Doctor of Science (DSc)

State registration number

0524U000380

Thesis Registration Form

0524U000380.pdf

Applicant for

Specialization

  • 01.04.10 - Фізика напівпровідників і діелектриків

18-12-2024

Specialized Academic Board

Д 64.169.01

Institute for Scintillation Materials of National Academy of Science of Ukraine

Essay

In the thesis the methods of optical spectroscopy were used to study the mechanisms of formation of pro- and antioxidant properties of dielectric rare earth orthovanadate nanocrystals REVO4 (RE = Gd, Y, La) and methods of controlling the redox properties of nanocrystals using external influence and changing their structure was established. The dependence of the structural, optical, and redox properties of rare-earth orthovanadate nanocrystals REVO4:Eu3+ (RE = Gd, Y, La) on their size and the presence of dopant ions has been established. Using optical methods, particularly luminescence spectroscopy, the time-dependent changes in the redox properties of REVO4:Eu3+ (RE = Gd, Y, La) nanocrystals of different sizes in aqueous solutions have been identified, along with the mechanisms of generation/neutralization of reactive oxygen species, both under direct UV or X-ray irradiation and in its absence. The efficiency of non-radiative electronic excitation energy transfer and the generation of reactive oxygen species in the "orthovanadate nanocrystal – photosensitizer molecule" system under irradiation have been determined. Based on the conducted research and the experimental data obtained, approaches to controlling the redox properties of REVO4:Eu3+ (RE = Gd, Y, La) rare-earth orthovanadate nanocrystals have been proposed. It was shown that in (Gd,Y)VO4:Eu3+ nanocrystals (d=2 nm) due to their structure, more than 60% of vanadium ions are presented on the surface of NPs in lower oxidation states, i.e. V4+ and V3+. The coexistence of three oxidation states of vanadium ions is responsible for the observed reactive oxygen species scavenging activity of (Gd,Y)VO4:Eu3+ nanocrystals and, consequently, for their antioxidant properties both in cell-free media and in a cell suspension. The main mechanism of H2O2 decomposition is associated with CAT-like reactions that ensure the V4+/V5+ and V3+/V4+ redox cycling. Obtained experimental data and their analysis allow to conclude on the mechanisms of Eu3+ luminescence quenching in Eu3+-doped GdVO4 nanocrystals in water solution after exposure to H2O2: the decrease in the efficiency of non-radiative resonance energy transfer through the vanadate VO43- groups to Eu3+ ions due to the scattering effect of V4+ ions and the direct quenching of Eu3+ luminescence by -OH groups formed at the surface as a result of decomposition of H2O2. The analysis of the redox properties of nanocrystals in different conditions (UV- and X-ray irradiation, lipid autoxidation) allows their Janus-faced redox activity to be revealed for the first time. It has been shown that pro- or anti-oxidant activity depends on external conditions (presence or absence of irradiation and its type). At UV irradiation, nanocrystals increase sufficiently the reactive oxygen species amount in the water solutions and lipid suspensions. At X-ray irradiation and in lipid autoxidation experiments nanocrystals demonstrate reactive oxygen species scavenging ability. Obtained experimental results allow the complex non-linear pattern of hydroxyl radical generation dynamics at UV irradiation of small (Gd,Y)VO4:Eu3+ nanocrystals to be ascribed to two competitive mechanisms associated with hydroxyl radicals scavenging and production, respectively. The first slower part in the hydroxyl radical generation curve is associated with a predominate radical scavenging mechanism, the second faster part in the hydroxyl radicals generation curve is associated with a photo-catalytic action of (Gd,Y)VO4:Eu3+ nanocrystals. It was shown that REVO4:Eu3+ (RE = Gd, Y, La) nanocrystals exhibit pro-oxidant activity even in the absence of UV light (in the dark). The efficiency of superoxide and hydroxyl radical generation correlates with the size of nanocrystals and, consequently, the concentration of surface defects, especially oxygen vacancies. It was shown that doping with Eu3+ ions do impacts on the dark reactive oxygen species generation ability of small (Gd,Y)VO4:Eu3+ nanocrystals. UV-light pretreatment of the (Gd,Y)VO4:Eu3+ nanocrystals causes sufficient changes in their characteristic fluorescence spectrum that was ascribed to the Eu3+/Eu2+ reduction. Electrons stored in Eu2+ participate in electron transfer reactions with the production of superoxide radical. It was shown that small (Gd,Y)VO4:Eu3+ nanocrystals possess redox activity, and this redox activity can be triggered by altering conditions of nanocrystals pre-treatment. Nanocrystals, which were exposed to UV light before the experiment, reveal strong pro-oxidant activity. Key words: dielectric nanocrystal, rare-earth orthovanadate, luminescence, oxygen vacancies, reactive oxygen species.

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Research papers

P. O. Maksimchuk, K. O. Hubenko, M. Knupfer, V. V. Seminko, V. K. Klochkov, O. V. Sorokin, L. D. Demchenko, and S. L. Yefimova, “Microscopic Mechanisms of Luminescence Quenching in Eu3+-doped GdVO4 Nanoparticles under Hydrogen Peroxide Decomposition”, Journal of Molecular Liquids, vol. 400, p. 124510, 2024, DOI: https://doi.org/10.1016/j.molliq.2024.124510

P. O. Maksimchuk, K. O. Hubenko, M. Knupfer, V. V. Seminko, V. K. Klochkov, O. V. Tomchuk, N. S. Kavok, O. V. Sorokin, L. D. Demchenko, and S. L. Yefimova, “·OH-Free Catalytic Decomposition of H2O2 by GdVO4:Eu3+ Nanoparticles”, Journal of Physical Chemistry C, vol. 127, pp. 15206-15214, 2023, DOI: https://doi.org/10.1021/acs.jpcc.3c03209

P. Maksimchuk, K. Hubenko, V. Seminko, I. Bespalova, A. Sorokin, G. Grygorova, and S. Yefimova, “UV-Light-Activated (Gd,Y)VO4:Eu3+ Nanoparticles for Radiotherapy Enhancement”, Journal of Physical Chemistry C, vol. 126, рp. 9371-9377, 2022, DOI: https://doi.org/10.1021/acs.jpcc.2c01737

P. O. Maksimchuk, K. O. Hubenko, G. V. Grygorova, V. V. Seminko, I. I. Bespalova, A. V. Sorokin, and S. L. Yefimova, “Photobleaching of LnVO4:Eu3+ nanoparticles under UV-light irradiation: Effect of nanoparticle size”, Journal of Luminescence, vol. 242, p. 118593, 2022, DOI: https://doi.org/10.1016/j.jlumin.2021.118593

P. O. Maksimchuk, K. O. Hubenko, V. V. Seminko, V. L. Karbivskii, A. S. Tkachenko, and S. L. Yefimova, “High antioxidant activity of gadolinium–yttrium orthovanadate nanoparticles in cell-free and biological milieu”, Nanotechnology, vol. 33, Art no. 055701, 2022, DOI: https://doi.org/10.1088/1361-6528/ac31e5

P. O. Maksimchuk, K. O. Hubenko, G. V. Grygorova, A. V. Sorokin, V. K. Klochkov, and S. L. Yefimova, “The impact of Eu3+ ions on pro-oxidant activity of ReVO4:Eu3+ nanocrystals”, Journal of Physical Chemistry C, vol. 125, pp. 1564-1569, 2021, DOI: https://doi.org/10.1021/acs.jpcc.0c10028

P. O. Maksimchuk, S. L. Yefimova, V. V. Omielaieva, K. O. Hubenko, V. K. Klochkov, O. D. Opolonin, and Yu. V. Malyukin, “X-ray induced hydroxyl radical generation by GdYVO4:Eu3+ nanoparticles in aqueous solution: main mechanisms”, Crystals, vol. 10, p. 370, 2020, DOI: https://doi.org/10.3390/cryst10050370

S. L. Yefimova, P. O. Maksimchuk, K. O. Hubenko, V. V. Omielaieva, N. S. Kavok, V. K. Klochkov, Yu. V. Malyukin, and V. P. Semynozhenko, “Light-triggered redox activity of GdYVO4:Eu3+ nanoparticles”, Spectrochimica Acta A, vol. 242, Art no. 118741, 2020, DOI: https://doi.org/10.1016/j.saa.2020.118741

P. O. Maksimchuk, S. L. Yefimova, K. O. Hubenko, V. V. Omielaieva, N. S. Kavok, V. K. Klochkov, O. V. Sorokin, and Yu. V. Malyukin, “Dark Reactive Oxygen Species Generation in ReVO4:Eu3+ (Re = Gd, Y) Nanoparticles in Aqueous Solutions”, Journal of Physical Chemistry C, vol. 124, pp. 3843-3850, 2020, DOI: https://doi.org/10.1021/acs.jpcc.9b10143

S. L. Yefimova, P. O. Maksimchuk, K. A. Hubenko, V. K. Klochkov, A. V. Sorokin, and Yu. V. Malyukin, “Untangling the Mechanisms of GdYVO4:Eu3+ nanoparticle Photocatalytic Activity”, Colloids and Surfaces A, vol. 577, pp. 630-636, 2019, DOI: https://doi.org/10.1016/j.colsurfa.2019.06.028

S. L. Yefimova, P. O. Maksimchuk, V. V. Seminko, N. S. Kavok, V. K. Klochkov, K. A. Hubenko, A. V. Sorokin, I. Yu. Kurilchenko, and Yu. V. Malyukin, “Janus-faced redox activity of LnVO4:Eu3+ (Ln = Gd, Y, La) nanoparticles”, Journal of Physical Chemistry C, vol. 123, pp. 15323-15329, 2019, DOI: https://doi.org/10.1021/acs.jpcc.9b03040

K. O. Hubenko, S. L. Yefimova, T. N. Tkacheva, P. O. Maksimchuk, O. O. Sedyh, O. G. Viagin, A. V. Sorokin, and Yu. V. Malyukin, “Excimer emission of Acridine Orange adsorbed on Gadolinium-Yttrium orthovanadate nanoparticles”, Journal of Fluorescence, vol. 28, no. 4, pp. 943-949, 2018, DOI: https://doi.org/10.1007/s10895-018-2257-9

K. Hubenko, S. Yefimova, T. Tkacheva, P. Maksimchuk, I. Borovoy, V. Klochkov, N. Kavok, O. Opolonin, and Yu. Malyukin, “Reactive oxygen species generation in aqueous solutions containing GdVO4:Eu3+ nanoparticles and their complexes with Methylene Blue”, Nanoscale Research Letters, vol. 13, 2018, Art no. 100, DOI: https://doi.org/10.1186/s11671-018-2514-5

S. L. Yefimova, T. N. Tkacheva, P. O. Maksimchuk, I. I. Bespalova, K. O. Hubenko, I. A. Borovoy, G. V. Grygorova, V. P. Semynozhenko, R. S. Grynyov, A. V. Sorokin, and Yu. V. Malyukin, “Porous CaCO3 carriers loaded with scintillation nanoparticles and photosensitizer molecules for photodynamic activation”, Microporous and Mesoporous Materials, vol. 263, pp. 128–134, 2018, DOI: https://doi.org/10.1016/j.micromeso.2017.12.020

S. L. Yefimova, T. N. Tkacheva, P. O. Maksimchuk, I. I. Bespalova, K. O. Hubenko, V. K. Klochkov, A. V. Sorokin, and Yu. V. Malyukin, “GdVO4:Eu3+ nanoparticles – Methylene Blue complexes for PDT: Electronic excitation energy transfer study”, Journal of Luminescence, vol. 192, pp. 975–981, 2017, DOI: https://doi.org/10.1016/j.jlumin.2017.08.044

С. Л. Єфімова, П. О. Максимчук, В. К. Клочков, “Поліфункціональні редокс-активні нанокристали ортованадатів рідкісноземельних елементів”, Харків: ІСМА, 2023, 192 с.

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