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    Surface-Dependent Osteoblasts Response to TiO2 Nanotubes of Dfferent Crystallinity
    (Basel : MDPI, 2020) Khrunyk, Yuliya Y.; Belikov, Sergey V.; Tsurkan, Mikhail V.; Vyalykh, Ivan V.; Markaryan, Alexandr Y.; Karabanalov, Maxim S.; Popov, Artemii A.; Wysokowski, Marcin
    One of the major challenges of implantology is to design nanoscale modifications of titanium implant surfaces inducing osseointegration. The aim of this study was to investigate the behavior of rat osteoblasts cultured on anodized TiO2 nanotubes of different crystallinity (amorphous and anatase phase) up to 24 days. TiO2 nanotubes were fabricated on VT1–0 titanium foil via a two-step anodization at 20 V using NH4F as an electrolyte. Anatase-phase samples were prepared by heat treatment at 500 °C for 1 h. VT1–0 samples with flat surfaces were used as controls. Primary rat osteoblasts were seeded over experimental surfaces for several incubation times. Scanning electron microscopy (SEM) was used to analyze tested surfaces and cell morphology. Cell adhesion and proliferation were investigated by cell counting. Osteogenic differentiation of cells was evaluated by qPCR of runt-related transcription factor 2 (RUNX2), osteopontin (OPN), integrin binding sialoprotein (IBSP), alkaline phosphatase (ALP) and osteocalcin (OCN). Cell adhesion and proliferation, cell morphology and the expression of osteogenic markers were affected by TiO2 nanotube layered substrates of amorphous and anatase crystallinity. In comparison with flat titanium, along with increased cell adhesion and cell growth a large portion of osteoblasts grown on the both nanostructured surfaces exhibited an osteocyte-like morphology as early as 48 h of culture. Moreover, the expression of all tested osteogenic markers in cells cultured on amorphous and anatase TiO2 nanotubes was upregulated at least at one of the analyzed time points. To summarize, we demonstrated that amorphous and anodized TiO2 layered substrates are highly biocompatible with rat osteoblasts and that the surface modification with about 1500 nm length nanotubes of 35 ± 4 (amorphous phase) and 41 ± 8 nm (anatase phase) in diameter is sufficient to induce their osteogenic differentiation. Such results are significant to the engineering of coating strategies for orthopedic implants aimed to establish a more efficient bone to implant contact and enhance bone repair. © 2020 by the author. Licensee MDPI, Basel, Switzerland.
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    Plant Coumarins with Anti-HIV Activity: Isolation and Mechanisms of Action
    (Basel : Molecular Diversity Preservation International, 2023) Sharapov, Ainur D.; Fatykhov, Ramil F.; Khalymbadzha, Igor A.; Zyryanov, Grigory V.; Chupakhin, Oleg N.; Tsurkan, Mikhail V.
    This review summarizes and systematizes the literature on the anti-HIV activity of plant coumarins with emphasis on isolation and the mechanism of their antiviral action. This review summarizes the information on the anti-HIV properties of simple coumarins as well as annulated furano- and pyranocoumarins and shows that coumarins of plant origin can act by several mechanisms: inhibition of HIV reverse transcriptase and integrase, inhibition of cellular factors that regulate HIV-1 replication, and transmission of viral particles from infected macrophages to healthy ones. It is important to note that some pyranocoumarins are able to act through several mechanisms or bind to several sites, which ensures the resistance of these compounds to HIV mutations. Here we review the last two decades of research on the anti-HIV activity of naturally occurring coumarins.