Luminescence of [Ru(bpy)₂(dppz)]²⁺ Bound to RNA Mismatches

The luminescence of <i>rac</i>-[Ru­(bpy)₂(dppz)]²⁺ (bpy = 2,2′-bipyridine and dppz = dipyrido­[3,2-<i>a</i>:2′,3′-<i>c</i>]­phenazine) was explored in the presence of RNA oligonucleotides containing a single RNA mismatch (CA and GG) in order to develop a probe for RNA mismatches. While there is minimal luminescence of [Ru­(bpy)₂(dppz)]²⁺ in the presence of matched RNA due to weak binding, the luminescence is significantly enhanced in the presence of a single CA mismatch. The luminescence differential between CA mismatched and matched RNA is substantially higher compared to the DNA analogue, and therefore, [Ru(bpy)₂(dppz)]²⁺ appears to be also a sensitive light switch probe for a CA mismatch in duplex RNA. Although the luminescence intensity is lower in the presence of RNA than DNA, Förster resonance energy transfer (FRET) between the donor ruthenium complex and FRET acceptor SYTO 61 is successfully exploited to amplify the luminescence in the presence of the mismatch. Luminescence and quenching studies with sodium iodide suggest that [Ru­(bpy)₂(dppz)]²⁺ binds to these mismatches via metalloinsertion from the minor groove. This work provides further evidence that metalloinsertion is a general binding mode of octahedral metal complexes to thermodynamically destabilized mismatches not only in DNA but also in RNA

Multifunctional Mesoporous Nanocomposites with Magnetic, Optical, and Sensing Features: Synthesis, Characterization, and Their Oxygen-Sensing Performance

In this paper, the fabrication, characterization, and application in oxygen sensing are reported for a novel multifunctional nanomaterial of [Ru­(bpy)₂phen-MMS] (bpy, 2,2′-bipyridyl; phen, phenathrolin) which was simply prepared by covalently grafting the ruthenium­(II) polypyridyl compounds into the channels of magnetic mesoporous silica nanocomposites (MMS). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, N₂ adsorption–desorption, a superconducting quantum interference device, UV–vis spectroscopy, and photoluminescence spectra were used to characterize the samples. The well-designed multifunctional nanocomposites show superparamagnetic behavior and ordered mesoporous characteristics and exhibit a strong red-orange metal-to-ligand charge transfer emission. In addition, the obtained nanocomposites give high performance in oxygen sensing with high sensitivity (<i>I</i>₀/<i>I</i>₁₀₀ = 5.2), good Stern–Volmer characteristics (<i>R</i>² = 0.9995), and short response/recovery times (<i>t</i>↓ = 6 s and <i>t</i>↑ = 12 s). The magnetic, mesoporous, luminescent, and oxygen-sensing properties of this multifunctional nanostructure make it hold great promise as a novel multifunctional oxygen-sensing system for chemical/biosensor

Targeted Delivery System Based on Magnetic Mesoporous Silica Nanocomposites with Light-Controlled Release Character

We report the facile synthesis and easy operation of a smart delivery system based on core–shell structured magnetic mesoporous silica nanocomposites covalently grafted with light-responsive azobenzene derivatives, which integrates magnetic targeting and stimuli-responsive release property. Irradiation with visible light triggers the release of guest molecules loaded in the mesopores

Solubility of Benzothiazolium Ionic Liquids in Water and in Furfural

The solubility of benzothiazolium ionic liquids in water and in furfural was determined by static analytical and dynamic methods, respectively. The solid–liquid equilibrium data were correlated by using the nonrandom two-liquid (NRTL), Wilson, modified Apelblat, and λ<i>h</i> models, respectively. Among the models, the modified Apelblat gave the best correlation results with the average relative deviation (ARD) of 2.02%. The effect of alkyl chain length on the solubility was discussed. The (liquid + liquid) phase equilibrium was observed in the system of benzothiazolium ionic liquids and water below the melting temperature of the ionic liquid. The solubility of benzothiazolium ionic liquids in furfural was much higher than in water, indicating the potential of application in extraction of furfural from aqueous solution

Luminescent Properties of Ruthenium(II) Complexes with Sterically Expansive Ligands Bound to DNA Defects

A new family of ruthenium­(II) complexes with sterically expansive ligands for targeting DNA defects was prepared, and their luminescent responses to base pair mismatches and/or abasic sites were investigated. Design of the complexes sought to combine the mismatch specificity of sterically expansive metalloinsertors, such as [Rh­(bpy)₂(chrysi)]³⁺ (chrysi = chrysene-5,6-quinone diimine), and the light switch behavior of [Ru­(bpy)₂(dppz)]²⁺ (dppz = dipyrido­[3,2-<i>a</i>:2′,3′-<i>c</i>]­phenazine). In one approach, complexes bearing analogues of chrysi incorporating hydrogen-bonding functionality similar to dppz were synthesized. While the complexes show luminescence only at low temperatures (77 K), competition experiments with [Ru­(bpy)₂(dppz)]²⁺ at ambient temperatures reveal that the chrysi derivatives preferentially bind DNA mismatches. In another approach, various substituents were introduced onto the dppz ligand to increase its steric bulk for mismatch binding while maintaining planarity. Steady state luminescence and luminescence lifetime measurements reveal that these dppz derivative complexes behave as DNA “light switches” but that the selectivity in binding and luminescence with mismatched/abasic versus well-matched DNA is not high. In all cases, luminescence depends sensitively upon structural perturbations to the dppz ligand

Development of Purine-Based Hydroxamic Acid Derivatives: Potent Histone Deacetylase Inhibitors with Marked in Vitro and in Vivo Antitumor Activities

In the present study, a series of novel histone deacetylase (HDAC) inhibitors using the morpholinopurine as the capping group were designed and synthesized. Several compounds demonstrated significant HDAC inhibitory activities and antiproliferative effects against diverse human tumor cell lines. Among them, compound <b>10o</b> was identified as a potent class I and class IIb HDAC inhibitor with good pharmaceutical profile and druglike properties. Western blot analysis further confirmed that <b>10o</b> more effectively increased acetylated histone H3 than panobinostat (LBH-589) and vorinostat (SAHA) at the same concentration in vitro. In in vivo efficacy evaluations of HCT116, MV4-11, Ramos, and MM1S xenograft models, <b>10o</b> showed higher efficacy than SAHA or LBH-589 without causing significant loss of body weight and toxicity. All the results indicated that <b>10o</b> could be a suitable candidate for treatment of both solid and hematological cancer