New TEMPO–Appended 2,2′-Bipyridine-Based Eu(III), Tb(III), Gd(III) and Sm(III) Complexes: Synthesis, Photophysical Studies and Testing Photoluminescence-Based Bioimaging Abilities
Nataliya V. Slovesnova,
Artem S. Minin,
Anna V. Belousova,
Aleksey A. Ustyugov,
Kirill D. Chaprov,
Alexey P. Krinochkin,
Maria I. Valieva,
Yaroslav K. Shtaitz,
Ekaterina S. Starnovskaya,
Igor L. Nikonov,
Anton N. Tsmokalyuk,
Grigory A. Kim,
Sougata Santra,
Dmitry S. Kopchuk,
Emiliya V. Nosova,
Grigory V. Zyryanov
Affiliations
Nataliya V. Slovesnova
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Artem S. Minin
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Anna V. Belousova
Institute of Immunology and Physiology, Ural Branch of the RAS 106, Pervomaiskaya Street, 620049 Yekaterinburg, Russia
Aleksey A. Ustyugov
Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry of the RAS 1, Severniy Proezd, 142432 Chernogolovka, Russia
Kirill D. Chaprov
Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry of the RAS 1, Severniy Proezd, 142432 Chernogolovka, Russia
Alexey P. Krinochkin
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Maria I. Valieva
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Yaroslav K. Shtaitz
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Ekaterina S. Starnovskaya
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Igor L. Nikonov
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Anton N. Tsmokalyuk
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Grigory A. Kim
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Sougata Santra
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Dmitry S. Kopchuk
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Emiliya V. Nosova
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Grigory V. Zyryanov
Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
Linked to Alzheimer’s disease (AD), amyloids and tau-protein are known to contain a large number of cysteine (Cys) residues. In addition, certain levels of some common biogenic thiols (cysteine (Cys), homocysteine (Hcy), glutathione (GSH), etc.) in biological fluids are closely related to AD as well as other diseases. Therefore, probes with a selective interaction with the above-mentioned thiols can be used for the monitoring and visualizing changes of (bio)thiols in the biological fluids as well as in the brain of animal models of Alzheimer’s disease. In this study, new Eu(III), Tb(III), Gd(III) and Sm(III) complexes of 2,2′-bipyridine ligands containing TEMPO fragments as receptor units for (bio)thiols are reported. The presence of free radical fragments of the ligand in the complexes was proved by using the electronic paramagnetic resonance (EPR) method. Among all the complexes, the Eu(III) complex turned out to be the most promising one as luminescence- and spin-probe for the detection of biogenic thiols. The EPR and fluorescent titration methods showed the interaction of the resulting complex with free Cys and GSH in solution. To study the practical applicability of the probes for the monitoring of AD in-vivo, by using the above-mentioned Eu(III)-based probe, the staining of the brain of mice with amyloidosis and Vero cell cultures supplemented with the cysteine-enriched medium was studied as well as the fluorescence titration of Bovine Serum Albumin, BSA (as the model for the thiol moieties containing protein), was carried out. Based on the results of fluorescence titration, the formation of a non-covalent inclusion complex between the above-mentioned Eu(III) complex and BSA was suggested.
