Photoinduced DNA Cleavage and Photocytotoxic of Phenanthroline-Based Ligand Ruthenium Compounds.

The photophysical and biological properties of two new phenanthroline-based ligand ruthenium complexes were investigated in detail. Their DNA interaction modes were determined to be the intercalation mode using spectra titration and viscosity measurements. Under irradiation, obvious photo-reduced DNA cleavages were observed in the two complexes via singlet oxygen generation. Furthermore, complex 2 showed higher DNA affinity, photocleavage activity, and singlet oxygen quantum yields than complex 1. The two complexes showed no toxicity towards tumor cells (HeLa, A549, and A375) in the dark. However, obvious photocytotoxicities were observed in the two complexes. Complex 2 exhibited large PIs (phototherapeutic indices) (ca. 400) towards HeLa cells. The study suggests that these complexes may act as DNA intercalators, DNA photocleavers, and photocytotoxic agents.

Nitro-Substituted Ruthenium(II) Complex: A New Strategy for a G-Quadruplex DNA Fluorescent Probe.

A new strategy for a G-quadruplex fluorescent probe based on a nitro-substituted ruthenium complex is described. G-quadruplex DNA can be distinguished from double- or single-strand DNA by the naked eye. This ability originates from variation of the degree of protection of the nitro group on the complex from water by G-quadruplex and other structure DNAs.

miR­488­3p alleviates neuropathic pain by regulating target gene ROCK1.

The function of microRNA (miRNA) in neuropathic pain (NP) has received widespread attention. The current research sought to address the contribution of miR­488­3p in NP and its downstream mechanisms. The NP rat model was constructed by chronic constriction injury (CCI) surgery in rats. Regulation of miR­488­3p or Rho­associated coiled­coil­containing protein kinase 1 (ROCK1) in rats by intrathecal injection of lentivirus or plasmid. Real­time quantitative reverse transcription polymerase chain reaction (RT­qPCR) to examine the levels of miR­488­3p and ROCK1 in the dorsal root ganglion (DRG). Enzyme­linked immunosorbent assay (ELISA) to monitor the secretion of pro­inflammatory and anti­inflammatory factors. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) for the evaluation of mechanosensitive and thermal nociceptive hypersensitivity of NP behaviors. Validation of molecular mechanism  between miR­488­3p and ROCK1 using RNA immunoprecipitation assay and dual­luciferase reporter (DLR) assay. miR­488­3p was vigorously less expressed in the DRGs of CCI rats, while ROCK1 was upregulated. Elevated miR­488­3p alleviated the decrease of PWL and PWT in CCI rats, inhibited the secretion of pro­inflammatory factors, and enhanced anti­inflammatory factors levels. Mechanistically, ROCK1 was the target of miR­488­3p. Raised ROCK1 partially attenuated the mitigating effect of miR­488­3p on NP behavior and the suppression of inflammatory responses in rats. Current research demonstrated that miR­488­3p may be a novel therapeutic target for NP.

Heteroatom-doped carbon sheets as metal-free electrocatalysts for promoting the oxygen reduction reaction in Zn-air batteries.

Zn-air batteries are promising energy devices for future sustainable development. It is crucial to promote the cathodic reaction, oxygen reduction reaction (ORR), by applying active electrocatalysts. Herein, a metal-free ORR electrocatalyst has been fabricated by doping S and N atoms into carbon sheets (S-N-C), and it displays high ORR activity and outstanding performance in Zn-air batteries. The S-N-C electrocatalyst exhibits remarkable ORR activity with a half-wave potential of 0.89 V, which is far exceeding that of the commercial Pt/C benchmark and most reported carbon-based electrocatalysts. A full-cell Zn-air battery device with S-N-C as a cathode catalyst is demonstrated, which delivers high power density and good durability.

Anticancer activity, topoisomerase I inhibition, DNA 'light switch' behavior and molecular docking of two ruthenium complexes containing phenazine ring.

Ruthenium(II) complexes containing phenazine ring have attracted attention to design as 'molecular light switches'. In this study, we synthesized two ruthenium complexes containing phenazine ring and studied their abilities to function as DNA intercalators, DNA 'light switches', DNA topo I inhibitors, DNA photocleavers and potential antitumor reagents. [Ru(bpy)2(mbipz)](PF6)2 (1) (bpy = 2,2'-bipyridine, mbipz = 2-(4'-methyl-bipyridine-4-yl)-1H-imidazo[4,5-b]phenazine) exhibited off-on type DNA 'light swtich' behavior. DNA binding modes of the two complexes were determined as intercalation by using UV-vis spectra, emission spectra, viscosity and molecular docking experiments. DNA photocleavage experimental results showed that the two ruthenium complexes effectively cleave plasmid DNA by producing singlet oxygen. Furthermore, they displayed good topo I inhibition activities. We further found that the two complexes displayed good antitumor activities against Eca-109 cells and A549 cells. The results demonstrated that introduction of phenazine ring will be helpful to design DNA 'light switch' based on ruthenium complex.Communicated by Ramaswamy H. Sarma.