Craig Bennett

Tungstate based poly(ionic liquid) entrapped magnetic nanoparticles: a robust oxidation catalyst

A novel magnetically recoverable oxidation catalyst was prepared in which magnetic nanoparticles were entrapped in a tungstate functionalized poly(ionic liquid) matrix. Using H2O2 as an oxidant, a wide range of substrates including alcohols, sulfides and olefins were selectively oxidized with excellent yields. The resulting catalyst was characterized by FTIR, TGA, SEM, TEM, XRD, XRF, CHN, vibrating sample magnetometer (VSM) and atomic adsorption spectroscopy (AAS). The catalyst can be readily recovered and reused at least ten times under the described reaction conditions without significant loss of reactivity.

Preparation of porous graphene oxide/hydrogel nanocomposites and their ability for efficient adsorption of methylene blue

Porous nanocomposite hydrogels were prepared using CaCO3 particles as solid porogens. The hydrogels were prepared by polymerization and grafting of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid onto the starch in the presence of CaCO3 and graphene oxide. CaCO3 solid porogens were then removed by washing with acid and porous structures were obtained. The prepared hydrogels were used as adsorbents for methylene blue as a model cationic dye; and a very high adsorption capacity, up to 714.29 mg g−1, was obtained. Kinetics and isotherms of adsorption and the effect of porosity of hydrogel as well as other experimental conditions were also investigated. The prepared adsorbents were recovered and reused for several cycles, and high removal efficiency was observed even after five cycles of adsorption.

Magnetic pH-responsive nanocarrier with long spacer length and high colloidal stability for controlled delivery of doxorubicin

A novel magnetic nanocarrier with long spacer length and high colloidal stability has been prepared for effective delivery of doxorubicin (DOX). First, poly(amidoamine) (PAMAM) dendrimer was grown up onto the surface of superparamagnetic iron oxide nanoparticles to increase the loading amount of amine groups. Then, terminal amine groups were functionalized by polyethylene glycol dimethylester to increase the spacer length. Then anticancer drug DOX was covalently attached onto the system by hydrazone bond to forms a pH-sensitive nanocarrier. This system is designed to combine the advantage of magnetic targeting, high drug loading capacity, and controlled release.

Magnetic nanoparticles entrapped in the cross-linked poly(imidazole/imidazolium) immobilized Cu(II): an effective heterogeneous copper catalyst

Anchoring of copper sulfate in layered poly(imidazole-imidazolium) coated magnetic nanoparticles provided a highly stable, active, reusable, high loading, and green catalyst for the click synthesis of 1,2,3-triazoles via a one-pot cycloaddition of alkyl halide, azide, and alkyne (Cu-A3C). The catalyst was characterized by FTIR, TGA, TEM, SEM, XRD, EDAX, VSM and AAS. High selectivity, broad diversity of alkyl/benzyl bromide/chloride and alkyl/aryl terminal alkynes, and good to excellent yields of products were obtained using 0.7 mol% catalyst. The catalyst was readily recovered and reused up to 6 times without significant loss of activity.

Cross-linked poly(dimethylaminoethyl acrylamide) coated magnetic nanoparticles: a high loaded, retrievable, and stable basic catalyst for the synthesis of benzopyranes in water

A novel heterogeneous catalyst has been synthesized based on the distillation–precipitation–polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups using N,N-dimethylethylenediamine. The resulting poly(dimethylaminoethyl acrylamide) coated magnetic nanoparticles (MNP@PDMA) catalyst was characterized using an array of sophisticated analytical techniques, including FT-IR, TGA, SEM, TEM, CHN, vibrating sample magnetometer (VSM), and XRD analysis. The resulting heterogeneous base catalyst allowed the performance of a domino Knoevenagel condensation/Michael addition/cycloaddition reaction toward the synthesis of 4H-benzo[b]pyranes in excellent yields using water as the reaction medium. The multilayered and polymeric identity of the coated material on the surface of the magnetic nanoparticles provides many catalytic units resulting in the high loading level and high stability of the catalyst. Straightforward magnetic separation and recycling of the catalyst for up to 5 runs is possible without any significant loss of efficiency.

Chemisorption Mechanism of DNA on Mg/Fe Layered Double Hydroxide Nanoparticles: Insights into Engineering Effective SiRNA Delivery Systems

Layered double hydroxide nanoparticles (LDH NPs) have attracted interest as an effective gene delivery vehicle in biomedicine. Recent advances in clinic trials have demonstrated the efficacy of Mg/Fe LDHs for hyperphosphatemia treatment, but their feasibility for gene delivery has not been systematically evaluated. As a starting point, we aimed to study the interaction between oligo-DNA and Mg/Fe LDH NPs. Our investigation revealed the chemisorption mechanism of DNA on Mg/Fe LDH surfaces, wherein the phosphate backbone of the DNA polymer coordinates with the metal cations of the LDH lattice via the ligand-exchange process. This mechanistic insight may facilitate future gene delivery applications using Mg/Fe LDH NPs.

Highly dispersible bis-imidazolium/WO42− modified magnetic nanoparticles: a heterogeneous phase transfer catalyst for green and selective oxidations

A novel magnetically recoverable catalyst was prepared in which magnetic nanoparticles (MNPs) were functionalized by bis-imidazolium tungstate ionic liquid molecules. The resulting catalyst was highly dispersible in water and selectively oxidized a wide range of alcohols and sulfides using H2O2 as a green oxidant. The catalyst was easily recovered and reused at least 5 times under the described reaction conditions without any significant loss of reactivity.

PEG-co-Polyvinyl Pyridine Coated Magnetic Mesoporous Silica Nanoparticles for pH-Responsive Controlled Release of Doxorubicin

In the present work a pH responsive drug nanocarrier based on magnetic mesoporous silica nanoparticles (MMSN) and polyethylene glycol-co-polyvinyl pyridine (PEG-co-PVP) was prepared. The core-shell nanocarrier was formed due to electrostatic interaction between protonated polyvinyl pyridine and surface modified MMSN with carboxylate groups. This carrier was used for pH-controllable doxorubicin release. The maximum release was occurred at pH 5.5 (pH of endosomes). This carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-Vis spectrophotometer, scanning electron microscope, and high-resolution transmission electron microscope techniques. Also the zeta potential value and dynamic light scattering were measured. All characterizations confirmed the core-shell structure of the drug nanocarrier. GRAPHICAL ABSTRACT

Highly dispersible and magnetically recyclable poly(1-vinyl imidazole) brush coated magnetic nanoparticles: an effective support for the immobilization of palladium nanoparticles

A heterogeneous recoverable catalyst was prepared via the complexation of palladium onto the surface of magnetic nanoparticles coated by a poly(1-vinyl imidazole) brush. The stable, active and reusable catalyst was proven to be highly active in aerobic oxidation of primary and secondary alcohols with excellent yields. Only 0.1 mol% of the catalyst was used to oxidize 1 mmol of primary and secondary alcohols. The catalyst was readily recovered and reused up to 10 times under the described reaction conditions without significant loss of activity.

Adsorption of Oligo-DNA on Magnesium Aluminum-Layered Double-Hydroxide Nanoparticle Surfaces: Mechanistic Implication in Gene Delivery

Magnesium aluminum-layered double-hydroxide nanoparticles (LDH NPs) are promising drug-delivery vehicles for gene therapy, particularly for siRNA interference; however, the interactions between oligo-DNA and LDH surfaces have not been adequately elucidated. Through a mechanistic study, oligo-DNA initially appears to rapidly bind strongly to the LDH outer surfaces through interactions with their phosphate backbones via ligand exchange with OH- on Mg2+ centers and electrostatic forces with Al3+. These initial interactions might precede diffusion into interlayer spaces, and this knowledge can be used to design better gene therapy delivery systems.