Facile and Rapid Preparation of Ag@ZIF-8 for Carboxylation of Terminal Alkynes with CO in Mild Conditions. Shi Jialin,Zhang Lina,Sun Nannan,Hu Deng,Shen Qun,Mao Fang,Gao Qiang,Wei Wei ACS applied materials & interfaces Metal-organic frameworks (MOFs) are promising hosts for catalytic active sites due to their adjustable porosity and framework chemistry. Strategies to improve synergistic effects between the installed sites and the parent MOF are highly desired. Herein, a facile and rapid method for the preparation of Ag@ZIF-8 materials was reported. The materials were systematically characterized and used as catalysts for carboxylation of terminal alkynes via direct insertion of CO to the C(sp)-H bond (CTA). It was found that the integrity of the ZIF-8 structure could be retained upon Ag loading, but short-range crystalline ordering was modified. Two types Ag species could be installed, namely, highly dispersed Ag(I) in the backbone (Ag) and aggregated Ag(0) nanoparticles on the outer surface (Ag). The Ag sites are highly effective for the activation of terminal alkynes due to its high accessibility, while the Ag-modified ZIF-8 framework worked as a CO reservoir with enhanced affinity. Combination of these factors translated to high activity in the CTA process, the measured turnover frequency and time yield are among the highest among most heterogeneous catalysts. 10.1021/acsami.9b07991

Synergistic Wound Healing by Novel Ag@ZIF-8 Nanostructures. International journal of pharmaceutics In this paper, novel zeolitic imidazolate framework-8 (ZIF-8) functionalized with Ag (Ag@ZIF-8) nanoparticles were synthesized through a green, facile and environmental-friendly process for wound dressing applications. X-ray diffraction revealed that the ZIF-8 and Ag@ZIF-8 were successfully synthesized by green solvents at ambient temperature. Field-emission scanning electron microscopy indicated a homogeneous porous blend of ∼30 nm chitosan/bacterial cellulose (CS/BC) nanofibers embedded with ∼80-110 nm nanoparticles of the ZIF-8 and Ag@ZIF-8. Transmission electron microscopy revealed the Ag@ZIF-8 nanostructures consist of ZIF-8 cores that are covered by 5-20 nm Ag nanoparticles. MTT assay indicated excellent cell viability values of ∼115 and 109% for the CS/BC nanocomposites reinforced by ZIF-8 and Ag@ZIF-8 nanoparticles, respectively. The Ag-containing wound dressings showed 52-300% of effective antibacterial activities. Animal studies demonstrated excellent healing for the wound treated by CS/BC-25%Ag@ZIF-8 nanocomposite with ∼91% of wound closure after 14 days of treatment. Hematoxylin and eosin (H&E) staining revealed successful healing and tissue regeneration for the wounds treated using the CS/BC-Ag@ZIF-8 nanocomposites. This kind of nanocomposites with synergistic antimicrobial and bioactivity properties can be a promising candidate for regenerative medicine. 10.1016/j.ijpharm.2022.122339