Synthesis, Characterization, and Catalytic Property of a Hybrid Nanoscale Polyoxoniobate

Isolation of Cytochrome C for Proteomics with Lindqvist-type Polyiodate Modified Metal Organic Framework

Separation and purification of Cytochrome C (Cyt-C) is important for proteomic. High efficient and selective pretreatment method for Cyt-C in real samples are always needed. Herein, polyniobate (K₇H[Nb₆O₁₉]·13H₂O, Nb₆O₁₉) is modified on a metal-organic framework MIL-125(Ti) through intermolecular hydrogen bonds and an aqueous-stable composite Nb₆O₁₉/MIL-125(Ti) is successfully prepared to pretreat complex protein sample. Protein adsorption studies have shown that Nb₆O₁₉/MIL-125(Ti) can promote the selective adsorption of Cyt-C due to the synergistic effect of electrostatic and hydrogen-bond interactions. At pH=10.0 (Britton-Robinson buffer), the adsorption efficiency of 300 μL 100 μg·mL^-1 Cyt-C onto 1.0 mg Nb₆O₁₉/MIL-125(Ti) can reach 99.5%. The adsorption behavior of Cyt-C fits well with the Langmuir adsorption model, corresponding to a maximum theoretical adsorption capacity of 168.35 mg·g^-1. Using 3 mol·L^-1 NaCl as the eluent, a high elution efficiency of 92.19% is obtained. In addition, the results of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis confirm that Nb₆O₁₉/MIL-125(Ti) efficiently adsorbed Cyt-C from scrofa heart extraction. LC-MS/MS spectrometry results show that the purification of Cyt-C reduces the abundance from the 12th to the 154th place after Nb₆O₁₉/MIL-125(Ti) treatment. Moreover, low abundant proteins, e.g., Superoxide dismutase 1, IF rod domain-containing protein and Ubiquitin-60S ribosomal protein L40 were considerably enriched. These outcomes confirm the practicability of Nb₆O₁₉/MIL-125 (Ti) as a Cyt-C extractant has potential application value in scrofa heart proteomics.

A Cyclen-Functionalized Cobalt-Substituted Sandwich-Type Tungstoarsenate with Versatility in Removal of Methylene Blue and Anti-ROS-Sensitive Tumor Cells

Oxidative degradation by using reactive oxygen species (ROS) is an effective method to treat pollutants. The synthesis of artificial oxidase for the degradation of dyes is a hot spot in molecular science. In this study, a nanoscale sandwich-type polyoxometalate (POM) on the basis of a tetra-nuclear cobalt cluster and trivacant B-α-Keggin-type tungstoarsenate {[Co(C₈H₂₀N₄)]₄}{Co₄(H₂O)₂[HAsW₉O₃₄]₂}∙4H₂O (abbreviated as CAW, C₈H₂₀N₄ = cyclen) has been synthesized and structurally examined by infrared (IR) spectrum, ultraviolet–visible (UV–Vis) spectrum, X-ray photoelectron spectrum (XPS), single-crystal X-ray diffraction (SXRD), and bond valence sum (Σs) calculation. According to the structural analysis, the principal element of the CAW is derived from modifying sandwich-type polyanion {Co₄(H₂O)₂ [HAsW₉O₃₄]₂}^8– with four [Co(Cyclen)]²⁺, in which 1,4,7,10-tetraazacyclododecane (cyclen) is firstly applied to modify POM. It is also demonstrated that CAW is capable of efficiently catalyzing the production of ROS by the synergistic effects of POM fragments and Co–cyclen complexes. Moreover, CAW can interfere with the morphology and proliferation of sensitive cells by producing ROS and exhibits ability in specifically eliminating methylene blue (MB) dyes from the solution system by both adsorption and catalytic oxidation.

A Novel Tri-Coordination Zinc Complex Functionalized Silicotungstate with ROS Catalytic Ability and Anti-Tumor Cells Activity

Reactive oxygen species (ROS) can be used as an effective method to treat tumors. Artificial oxidase has received increasing attention as a catalyst for ROS generation in fields ranging from bioinorganic chemistry to pharmaceutical chemistry. In this study, an artificial oxidase based on a binuclear zinc complex and Keggin-type silicotungstate [Zn2(4,4′-bpy)(Phen)2][SiW12O40] (ZSW) (4,4′-bpy = 4,4′-bipyridine; Phen = 1,10-phenanthroline) was synthesized and structurally featured in terms of its X-ray photoelectron spectrum (XPS), bond valence sum (Σs) calculation, IR spectra, and single-crystal X-ray diffraction (SXRD). ZSW is an ionic compound in which the cation is a binuclear zinc complex [Zn2(4,4′-bpy)(Phen)2]4+ and the anion is a α-Keggin-type silicotungstate [SiW12O40]4– cluster. Notably, the Zn ions in the [Zn2(4,4′-bpy)(Phen)2] exist in tri-coordination, which was first obtained in polyoxometalate (POM) chemistry. It was also demonstrated that ZSW is capable of efficiently catalyzing the production of ROS, which, according to the computational calculations, may be due to the synergistic action of zinc complexes and POM building blocks. Furthermore, ZSW exhibited inhibition ability toward ROS-sensitive tumor cells, such as PC12 cells.