Local gene delivery via endovascular stents coated with dodecylated chitosan–plasmid DNA nanoparticles

Development of efficacious therapeutic strategies to prevent and inhibit the occurrences of restenosis after percutaneous transluminal coronary angioplasty is critical for the treatment of cardiovascular diseases. In this study, the feasibility and efficiency of stents coated with dodecylated chitosan–plasmid DNA nanoparticles (DCDNPs) were evaluated as scaffolds for localized and prolonged delivery of reporter genes into the diseased blood vessel wall. Dodecylated chitosan–plasmid DNA complexes formed stable positive charged nanospheres with mean diameter of approximately 90–180 nm and zeta potential of +28 ± 3 mV. As prepared DCDNPs were spray-coated on stents, a thin layer of dense DCDNPs was successfully distributed onto the metal struts of the endovascular stents as demonstrated by scanning electron microscopy. The DCDNP stents were characterized for the release kinetics of plasmid DNA, and further evaluated for gene delivery and expression both in vitro and in vivo. In cell culture, DCDNP stents containing plasmid EGFP-C1 exhibited high level of GFP expression in cells grown on the stent surface and along the adjacent area. In animal studies, reporter gene activity was observed in the region of the artery in contact with the DCDNP stents, but not in adjacent arterial segments or distal organs. The DCDNP stent provides a very promising strategy for cardiovascular gene therapy

Bimetallic docked covalent organic frameworks with high catalytic performance towards tandem reactions

Mn/Pd bimetallic docked covalent organic frameworks were fabricated via a programmed synthetic procedure. Within the framework, MnCl2 could only coordinate with the bipyridine ligands, while Pd(OAc)(2) could occupy the rest of the nitrogen sites. Such bimetallic docked materials showed high catalytic activity in a Heck-epoxidation tandem reaction

Rapid and Efficient Functionalized Ionic Liquid-Catalyzed Aldol Condensation Reactions Associated with Microwave Irradiation

Five quaternary ammonium ionic liquid (IL) and two tetrabutylphosphonium ILs were prepared and characterized. An environmentally benign and convenient functionalized ionic liquid catalytic system was thus explored in the aldol condensation reactions of aromatic aldehydes with acetone. The aldol reactions proceeded more efficiently through microwave-assisted heating than through conventional thermal heating. The yield of products obtained under microwave heating for 30 min was approximately 90%, and the ILs can be recovered and reused at least five times without apparent loss of activity. In addition, this catalytic system can be successfully extended to the Henry reactions

Bottom-up preparation of gold nanoparticle-mesoporous silica composite nanotubes as a catalyst for the reduction of 4-nitrophenol

Gold (Au) nanoparticle (NP)-mesoporous silica (SiO2) composite nanotubes were prepared by a bottom-up approach, in which Au NPs were anchored to the inner wall of mesoporous SiO2 tubular shells. In this composite, the agglomeration, exfoliation, and grain growth of Au NPs were restricted, and the loading and size of the catalyst NPs were easily tuned. The mesoporous shell, open ends, and one-dimensional passage of the SiO2 nanotubes all promote the diffusion of reactants, which enhanced the catalytic efficiency of this composite in the reduction of 4-nitrophenol, The Au NP-mesoporous SiO2 composite nanotubes also demonstrated good reusability, and no leaching or agglomeration of the Au NPs was observed during the catalytic reaction. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved

Nitrogen ligands in two-dimensional covalent organic frameworks for metal catalysis

We introduced bipyridine ligands into a series of two-dimensional (2D) covalent organic frameworks (COFs) using 2,2'-bipyridine-5,5'-dicarbaldehyde (2,2'-BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2'-BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyridine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be varied, with one ligand favoring binding in the space between adjacent COFs' layers and the other ligand favoring binding within the pores of the COFs. The Pd(II)-loaded COFs exhibited good catalytic activity for the Heck reaction. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved

bottomuppreparationofgoldnanoparticlemesoporoussilicacompositenanotubesasacatalystforthereductionof4nitrophenol

采用自下而上方法制备了金-介孔二氧化硅复合纳米管,其中金纳米粒子作为催化剂嵌在介孔二氧化硅纳米管管壁内侧.金纳米颗粒的团聚、脱落和晶粒尺寸生长都可以被有效限制,而且催化剂负载量和尺寸大小均可实现简单控制.管壁中的介孔孔道、纳米管末端开口以及一维中空管道可以协同促进反应物扩散,从而提高4-硝基苯酚还原反应活性.循环实验证明这种复合纳米管催化剂具有良好的可重复使用性,而且在反应过程中未出现金纳米粒子脱落或团聚现象

Facile fabrication of a novel microporous Schiff-base networks polymer membrane on surface modified porous alpha-Al2O3 support

A surface modification strategy was applied by using 3-aminopropyltriethoxysilane (APTES) covalent linkage between the Schiff-base networks (SNW) polymer layers and porous alpha-Al2O3 ceramic support. The SNW-1 polymer membrane and powders resulting from the polycondensation reaction between melamine and terephthalaldehyde without the polycondensation catalysts were investigated by SEM and FT-IR. The results show that the discrete and few covered polymer layers were formed on the unmodified porous alpha-Al2O3 support. In contrast, the uniform and compact SNW-1 polymer membrane was fabricated successfully on the APTES modified alpha-Al2O3 support by in-situ catalyst-free polycondensation method, indicating that the APTES surface modification facilitates the growth of the novel SNW-1 polymer membrane on the porous a-Al2O3 support. (C) 2014 Elsevier B.V. All rights reserved