[The effect of C-SiO2 composite films on corrosion resistance of dental Co-Cr alloy].

PURPOSE: To study the effect of carbon-silica composite films on corrosion resistance of Co-Cr alloy in simulated oral environment and provide evidences for clinical application of this new material. METHODS: Co-Cr alloy specimens were cut into appropriate size of 20 mm × 20 mm × 0.5 mm. Then, the carbon-silica composite films were spin-coated onto the specimens. Subsequently, ICP-AES was used to observe the Co, Cr, Mo ion concentrations. Finally, Tafel polarization curves of the specimens were used to measure the electrochemical corrosion resistance by electrochemical workstation. SAS8.0 software package was used for statistical analysis. RESULTS: The results of ICP-AES showed that the ion concentrations of Co, Cr, Mo of specimens coated with composite films in the testing liquid were significantly smaller than that of Co-Cr alloy specimens. Tafel polarization curves showed that in the specimens coated with composite films, the corrosion potential moved in the positive direction and increased from -0.261 V to -0.13 V. At the same time, the corrosion current density decreased from -5.0017µA/cm2 to -5.3006 µA/cm2. CONCLUSIONS: Carbon-silica composite films (silica=61.71wt %) can reduce the release of metal ions significantly and improve the corrosion resistance of Co-Cr alloys effectively. Carbon-silica composite films may be a promising dental material.

[Development of a method for methylated DNA enrichment with functionalized mesocellular silica foams immobilized with methyl CpG binding domain].

OBJECTIVE: To develop a method for enriching methylated DNA in clinical samples using mesocellular silica foams (MCFs) immobilized with methyl-CpG binding domain (MBD). METHODS: MCFs with ultra-large pore size were synthesized, functionalized and immobilized with GST-MBD. RESULTS: The large cage-like pore structures of MCF materials was retained after functionalization and immobilization, with pore diameter of 55 nm, window size of 30 nm, and a high pore volume of 1.0 cm(3)/g. The loading amount of MBD was as high as 53 wt%. Immobilized MBD showed high binding activity and stability. In a binding buffer with salt concentrations ranging 500-550 mmol/L, the MCF-MBD can selectively enrich methylated DNA from the mixed DNA solution. CONCLUSION: The MCF-MBD method may offer a better choice for high-throughout DNA methylation screening, and has laid a foundation for clinical application, prenatal diagnosis and research on DNA methylation-related genetic diseases.

A zinc(II) metal-organic framework based on triazole and dicarboxylate ligands for selective adsorption of hexane isomers.

A three-dimensional (3D) metal-organic framework {[Zn(2)(HBDC)(2)(dmtrz)(2)]·guest}(n) with pcu net has been solvothermally synthesized, which shows selective adsorption of linear and monobranched hexane isomers over a dibranched one.

Mesoporous biocompatible and acid-degradable magnetic colloidal nanocrystal clusters with sustainable stability and high hydrophobic drug loading capacity.

Fabrication of magnetic particles (MPs) with high magnetization and large surface area simultaneously is critical for the application of MPs in bioseparation and drug delivery but remains a challenge. In this article, we describe an unprecedented approach to synthesize mesoporous magnetic colloidal nanocrystal clusters (MCNCs) stabilized by poly(γ-glutamic acid) (PGA) with high magnetization, large surface area (136 m(2)/g) and pore volume (0.57 cm(3)/g), excellent colloidal stability, prominent biocompatibility, and acid degradability. This result provides the important step toward the construction of a new family of MCNCs and demonstrates its capacity in a "magnetic motor" drug delivery system. Here, as an example, we explore the applicability of as-prepared mesoporous MCNCs as hydrophobic drug delivery vehicles (paclitaxel as model drug), and the resultant loading capacity is as high as 35.0 wt %. The antitumor efficacy measured by MTT assay is significantly enhanced, compared with free drugs. Thus, combined with their inherent high magnetization, the mesoporous MCNCs pave the way for applying magnetic targeting drug carriers in antitumor therapeutics.

Design and generation of extended zeolitic metal-organic frameworks (ZMOFs): synthesis and crystal structures of zinc(II) imidazolate polymers with zeolitic topologies.

Attempts to create metal-organic frameworks (MOFs) with zeolitic topologies, metal (zinc(II) and cobalt(II)) imidazolates have repeatedly been used as the metal-organic motifs of inorganic silicate analogues. By modulating the synthetic strategy based on the solvothermal and liquid diffusion method, seven further MOFs (including at least three zeolitic MOFs) of zinc(II) imidazolates, [Zn(im)2.x G] (G=guest molecule, x=0.2-1) 1 a-7 a, have been successfully synthesized. Of these, 1 a-3 a are isostructural with the previously reported cobalt analogues 1 b-3 b, respectively, while 4 a-7 a are new members of the metal imidazolate MOF family. Complex 4 a exhibits a structure related to silicate CaAl2Si2O8 of CrB4 topology, but with a higher network symmetry; complex 5 a has a structure with zeolitic DFT topology that was discovered in zeolite-related materials of DAF-2, UCSB-3, and UCSB-3GaGe; complex 6 a demonstrates an unprecedented zeolite-like topology with one dimensional channels with 10-rings; and 7 a displays a structure of natural zeolite GIS (gismondine) topology. All of these polymorphous MOFs were created only by using certain solvents as structure-directing agents (SDAs). Further extensive metal-organic frameworks with zeolitic topologies can be envisaged if other solvents were to be used.

Two polymorphs of cobalt(II) imidazolate polymers synthesized solvothermally by using one organic template N,N-dimethylacetamide.

Two structurally different polymorphs of cobalt(II) imidazolate frameworks are solvothermally synthesized by using N,N-dimethylacetamide as a template: The polymorph 6 (a = 9.797 (4) angstroms, b = 15.301(6) angstroms, c =14.902(6) angstroms, beta = 98.904(6) degrees, monoclinic, P21/n) shows structures of silicate CaAl2Si2O8 with CrB4 topology, while polymorph 7 (a = 15.173(4) angstroms, b = 15.173(4) angstroms, c = 19.089(5) angstroms, Pbca) shows CaGa2O4-related topological structures. In addition, the 7' (a = 15.9712(18) angstroms, b = 15.9253(19) angstroms, c = 18.475(2) angstroms, Pbca), a compound isostructural with 7, is synthesized by using cyclohexanol as a template. Thus, these cobalt(II) imidazolate polymers are reminiscent of the zeolite syntheses in that not only the same topological structure can be synthesized by using the different organic templates, but also different topological structures can be synthesized by using the same organic template.