New
mononuclear and dinuclear Ru(II) coordination compounds with
the 2,7-bisbenzoimidazolyl-naphthyridine ligand have been synthesized
and characterized by UV–vis, NMR, and MALDI-TOF. The molecular
structures for Ru(II) compounds were determined by single-crystal
X-ray diffraction. With the expansion of ligand π-conjugation
and the increase in the complexed Ru number, the maximum emission
wavelength red-shifted from 696 to 786 nm. The binding mode between
complexes and DNA was predicted by molecular docking, which is intercalations
and π–π stacking interactions with the surrounding
bases. The intercalation mode of DNA binding was then determined by
DNA titration and ethidium bromide (EB) displacement experiments.
The antigrowth effects of complexes RuY, RuY1, and RuY2 were tested in HaCat (normal cells), HeLa
(cervical cancer), A549 (lung cancer), and A549/DDP (cisplatin-resistant
lung cancer) through the MTT assay. The dinuclear complex RuY2 was superior to mononuclear complexes and cisplatin in the cisplatin-resistant
cell line. Confocal imaging proved that the subcellular localization
of Ru(II) complexes was mitochondria; moreover, apoptosis was detected
by flow cytometry. All three complexes showed a dose-dependent manner
in all four cell lines. All Ru(II) complexes were found to have reactive
oxygen species (ROS). The finding indicated that these Ru(II) complexes
caused cell death by both DNA disruption and ROS. This study helps
to explore the potential of the polynuclear Ru(II) complexes for the
combination of NIR imaging and Pt-resistant cancer therapy.
Strontium zirconate (SrZrO3) has been considered as a promising thermal barrier coating (TBC) material for application in gas turbine engines; however, the phase transition problem limits its application. In this study, an Yb2O3 and Gd2O3 codoped SrZrO3 system with excellent properties was reported. Yb2O3‐Gd2O3 codoped SrZrO3 ceramic powders [Sr0.8(Zr0.9Yb0.05Gd0.05)O2.75, SZYG/YGZO], [Sr(Zr0.9Yb0.05Gd0.05)O2.95, SZYG] and pure SrZrO3 (SZO) powders were produced by a conventional solid‐state reaction method. The XRD and Raman results show that, the composite SZYG/YGZO ceramics consist of the SZO and Yb0.5Zr0.5O1.75 phases with a low thermal conductivity of ~1.3 W/(m·K) at 1000°C, which is at least 40% lower than that of the SZO ceramics. The TG‐DSC results show that the SZYG/YGZO ceramics have no phase transition in the temperature range of 600 to 1400°C. The thermal expansion coefficient of the SZYG/YGZO ceramics reaches 10.9 × 10−6 K−1 (1250°C). In addition, the fracture toughness of the SZYG/YGZO ceramics increases by more than 30% compared with the SZO ceramics, and this can be attributed to the presence of the Yb0.5Zr0.5O1.75 phase.
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