A new catalyst based on palladium nanoparticles immobilized on nano‐silica triazine dendritic polymer (Pdnp‐nSTDP) was synthesized and characterized by FT‐IR spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X‐ray, transmission electron microscopy and elemental analysis. The size of the palladium nanoparticles was determined to be 3.1±0.5 nm. This catalytic system showed high activity in the Suzuki–Miyaura cross‐coupling of aryl iodides, bromides and chlorides with arylboronic acids and also in the Heck reaction of these aryl halides with styrenes. These reactions were best performed in a dimethylformamide (DMF)/water mixture (1:3) in the presence of only 0.006 mol% and 0.01 mol% of the catalyst, respectively, under conventional conditions and microwave irradiation to afford the desired coupling products in high yields. The Pdnp‐nSTDP was also used as an efficient catalyst for the preparation of a series of star‐ and banana‐shaped compounds with a benzene, pyridine, pyrimidine or 1,3,5‐triazine unit as the central core. Moreover, the catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity.

No abstract

Silica-nanoparticle-supported copper-containing ionic liquid (SNIL-Cu­(II)) provided a highly stable, active, reusable, spherical, and solid-phase catalyst for click chemistry. The SNIL-Cu­(II) catalyst was readily prepared from 1,2-bis(4-pyridylthio)­ethane immobilized on silica nanoparticles modified with 3-chloropropyltrimethoxysilane and Cu­(OTf)2, and the morphology, structure, and properties of nanoparticles were investigated through different analytical tools. This catalytic system showed high activity in a one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles by click reactions between a variety of alkynes, organic halides, and sodium azide at room temperature in aqueous polyethylene glycol as a green medium with a high turnover frequency (up to 7920 h–1). Moreover, the SNIL-Cu­(II) was also used as an efficient catalyst for the preparation of a series of multifold 1,4-disubstituted 1,2,3-triazoles. Also, this unique catalyst was readily reused without any decrease in its catalytic activity to give the corresponding triazoles quantitatively.

Bacterial adhesion and subsequent biofilm formation on metals such as aluminum (Al) alloys lead to serious issues in biomedical and industrial fields from both an economical and health perspective. Here, we showed that a careful manipulation of Al surface characteristics via a facile two-steps superhydrophobic modification can provide not only biocompatibility and an ability to control protein adsorption and bacterial adhesion, but also address the issue of apparent long-term toxicity of Al-alloys. To find out the roles of surface characteristics, surface modification and protein adsorption on microbial adhesion and biofilm formation, the surfaces were systematically characterized by SEM, EDX, XPS, AFM, FTIR, water contact angle (WCA) goniometry, surface free energy (SFE) measurement, MTT, Bradford, Lowry and microtiter plate assays and also flow-cytometry and potentiostat analyses. Results showed that WCA and SFE changed from 70° to 163° and 36.3 to 0.13 mN m(-1) , respectively. The stable and durable modification led to a substantial reduction in static/dynamic BSA adsorption. The effect of such a treatment on the biofilm formation was analyzed by using three different bacteria of Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus. The microtiter plate assay and flow cytometry analysis showed that the modification not only could substantially reduce the bacterial adhesion but this biofouling resistance is independent of bacterium type. An excellent cell viability after exposure of HeLa cells to waters incubated with the modified samples was observed. Finally, the corrosion rate reduced sharply from 856.6 to 0.119 MPY after superhydrophobic modifications, which is an excellent stable corrosion inhibition property. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2220-2233, 2016.

Although several strategies are now available for immobilization of enzymes to magnetic nanoparticles for bioapplications, little progresses have been reported on the use of dendritic or hyperbranched polymers for the same purpose. Herein, we demonstrated synthesis of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG) and a derivative conjugated with citric acid (MNP/HPG-CA) as unique and convenient nanoplatforms for immobilization of enzymes. Then, an important industrial enzyme, xylanase, was immobilized on the nanocarriers to produce robust biocatalysts. A variety of analytical tools were used to study the morphological, structural, and chemical properties of the biocatalysts. Additionally, the results of biocatalyst systems exhibited the substantial improvement of reactivity, reusability, and stability of xylanase due to this strategy, which might confer them a wider range of applications.