Hyperbranched polymer mediated fabrication of water soluble carbon nanotube-metal nanoparticle hybrids

Carbonylative Suzuki-Miyaura cross-coupling by immobilized Ni@Pd NPs supported on carbon nanotubes

In this study, a novel carbon nanotube (CNT) based nanocatalyst (Ni@Pd/CNT) was synthesized by modifying CNTs using Ni@Pd core–shell nanoparticles (NPs). Ni@Pd/CNT was used in catalytic carbonylative cross-coupling between 4-iodoanisole and phenylboronic acid. The Ni@Pd NPs possessed a magnetic nickel (Ni) core with a palladium (Pd) structural composite shell. Thus, the use of Ni had led to a reduced consumption of Pd without sacrificing the overall catalytic performance, simultaneously making it reusable as it could be conveniently recovered from the reaction mixture by using an external magnetic field. Immobilization of the Ni@Pd NPs on carbon nanotubes not only prevented their aggregation, but also significantly enhanced the accessibility of the catalytically active sites. The abovementioned approach based on carbon nanotubes and Ni@Pd NPs provided a useful platform for the fabrication of noble-metal-based nanocatalysts with easy accessibility and low cost, which may allow for an efficient green alternative for various catalytic reductions.

In this study, a novel carbon nanotube (CNT) based nanocatalyst (Ni@Pd/CNT) was synthesized by modifying CNTs using Ni@Pd core–shell nanoparticles (NPs).

Facile Preparation of Carbon Nanotube-Cu2O Nanocomposites as New Catalyst Materials for Reduction of P-Nitrophenol

The effective synthesis and self-assembly of nanocomposites were of key importance for a broad range of nanomaterial applications. In this work, new carbon nanotube (CNT)-Cu2O nanocomposites were successfully synthesized via a facile approach. CNT was selected as the anchoring substrate to load Cu2O nanoparticles to prepare composite catalysts with well stability and good reusability. It is discovered that the prepared CNT-Cu2O nanocomposite materials could be effectively controlled via regulating preparation temperature and time without the use of any stabilizing agents. The nanostructures of synthesized composites were well characterized by many techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). And the prepared CNT-Cu2O nanocomposites with optimized preparation conditions as new catalyst displayed excellent catalytic performance on the reduction reaction of p-nitrophenol, demonstrating potential applications for environmental governance and composite materials.

Polyglycerol mediated covalent construction of magnetic mesoporous silica nanohybrid with aqueous dispersibility for drug delivery

Construction of nanohybrids with chemical and colloidal stability is of great importance for the exploration of their potential applications in biomedical field. In this work, a versatile strategy based on polyglycerol (PG) mediated covalent linkage is developed to fabricate a core-satellite nanohybrid, termed MMSN, consisting of a mesoporous silica nanoparticle (MSN) as a core and many superparamagnetic iron oxide nanoparticles (SPION) on the outer surface. In this synthetic strategy, the PG grafted SPION is derivatized to convert partial periphery hydroxyl groups to carboxyl moieties, followed by attachment to aminated MSN through amide bonds. The PG layer accounting for ~17wt% of MMSN not only serves as a tether to connect the two nanoparticles but also greatly enhances the colloidal stability of the nanohybrid, resulting in no significant change in hydrodynamic diameter and zeta potential during four months. Taking advantage of the combined porosity and magnetic property of the nanohybrid, a photosensitizer chlorin e6 (Ce6) is loaded on MMSN and efficiently delivered into target cells under magnetic guidance, leading to an enhanced efficacy of photodynamic therapy (PDT). The versatile strategy presented here opens up a new route to rational design and fabrication of multifunctional nanohybrids for various biomedical purposes.

Pd/APTPOSS@KCC-1 as a new and efficient support catalyst for C–H activation

In this study, KCC-1 was functionalized with APTPOSS groups acting as the strong performers so that the Pd NPs were well-dispersed on the fibers of the KCC-1 microspheres.

Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range

The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3', 5, 5'-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range.

Rational Design of Multiamphiphilic Polymer Compatibilizers: Versatile Solubility and Hybridization of Noncovalently Functionalized CNT Nanocomposites

The design of amphiphilic polymer compatibilizers for solubility manipulation of CNT composites was systematically generalized in this study. Structurally tailored multiamphiphilic compatibilizer were designed and synthesized by applying simple, high-yield reactions. This multiamphiphilic compatibilizer was applied for noncovalent functionalization of CNTs as well as provided CNTs with outstanding dispersion stability, manipulation of solubility, and hybridization with Ag nanoparticles (NPs). With regard to the dispersion properties, superior records in maximum concentration (2.88-3.10 mg/mL in chloroform), and mass ratio of the compatibilizer for good CNT dispersion (36 wt %) were achieved by MWCNTs functionalized with a multiamphiphilic block copolymer compatibilizer. In particular, the solubility limitations of MWCNT dispersion in solvents ranging from toluene (nonpolar) to aqueous solution (polar) are surprisingly resolved by introducing this multiamphiphilic polymer compatibilizer. Furthermore, this polymer compatibilizer allowed the synthesis of the hybrid CNT nanocomposites with Ag nanoparticles by an in situ nucleation process. As such, the multiamphiphilic compatibilizer candidate as a new concept for the noncovalent functionalization of CNTs can extend their use for a wide range of applications.

Polyamidoamine and polyglycerol; their linear, dendritic and linear–dendritic architectures as anticancer drug delivery systems

This review covers the latest advances in the conjugation of chemotherapeutics such as doxorubicin, paclitaxel, methotrexate, fluorouracil and cisplatin to dendritic polymers, including polyamidoamine dendrimers, hyperbranched polyglycerols and their linear analogues, with a focus on their cytotoxicity, biodistribution and biodegradability.

Enhanced catalytic and antibacterial activities of silver nanoparticles immobilized on poly(N-vinyl pyrrolidone)-grafted graphene oxide

PNVP grafted on GO regulates the size of Ag nanoparticles and enhances the catalytic and antibacterial properties along with increase in the dispersibility of GO.

A plasmon-assisted fluoro-immunoassay using gold nanoparticle-decorated carbon nanotubes for monitoring the influenza virus

A plasmon-assisted fluoro-immunoassay (PAFI) was developed for the detection of the influenza virus by using Au nanoparticle (Au NP)-decorated carbon nanotubes (AuCNTs) that were synthesized using phytochemical composites at room temperature in deionized water. Specific antibodies (Abs) against the influenza virus were conjugated onto the surface of AuCNTs and cadmium telluride quantum dots (QDs), which had a photoluminescence intensity that varied as a function of virus concentration and a detection limit of 0.1 pg/mL for all three types of influenza viruses examined. The clinically isolated influenza viruses (A/Yokohama/110/2009 (H3N2)) were detected in the range of 50-10,000 PFU/mL, with a detection limit of 50 PFU/mL. From a series of proof-of-concept and clinical experiments, the developed PAFI biosensing system provided robust signal production and enhancement, as well as an excellent selectivity and sensitivity for influenza viruses. This nanoparticle-based technique could be potentially developed as an efficient detection platform for the influenza virus.

Covalently functionalized carbon nanotube supported Pd nanoparticles for catalytic reduction of 4-nitrophenol

Carbon nanotubes (CNTs) were covalently functionalized via 1,3-dipolar cycloaddition reaction under microwave conditions. The functionalized CNTs were characterized by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), N2 adsorption isotherms and Raman spectroscopy. The surface concentration of phenolic hydroxyl groups on the surface of CNTs was adjusted by varying the reaction temperature. In addition, we prepared Pd nanoparticle/CNT (Pd NP/CNT) nanocomposites through strong electrostatic adsorption and hydrogen reduction. The results indicated that the functional groups could not only improve the dispersion of CNTs in water, but also enhance the interaction between Pd precursors and CNTs, thus preventing small Pd NPs (average diameter of 1.5 nm) from agglomerating. Furthermore, the Pd NP/CNT-220 nanocomposites showed high catalytic activity for the reduction of 4-nitrophenol. The turnover frequency (TOF) of this catalyst was up to 18 min(-1), which was attributed to the small size and uniform distribution of Pd NPs on the surface of CNTs.