Carboxylated Chitosan Nanocrystals: A Synthetic Route and Application as Superior Support for Gold-Catalyzed Reactions.

In this study, we demonstrate for the first time the fabrication of carboxylated chitosan nanocrystals (ChsNC) with high degree of deacetylation (DDA) at >80% and narrow size distribution. We also studied its application as a sustainable support material for metal-based catalysts. Carboxylated chitin nanocrystals (ChNCs) were initially prepared through partial cleavage of glycosidic bonds in chitin by ammonium persulfate, with concurrent oxidation of chitin C6 primary alcohols to produce carboxylate groups on the surface of the ChNCs.

Ensemble and Single Particle Fluorescence Characterization of Dye-Labeled Cellulose Nanocrystals.

Cellulose nanocrystals (CNCs) have been covalently labeled with both fluorescein and rhodamine and studied by a combination of UV-vis absorption spectroscopy and ensemble and single molecule fluorescence spectroscopy. For all samples, the fluorescence anisotropy and lifetimes were consistent with effects expected for covalently bound dye molecules. Low dye loading levels (∼0.

Monitoring of potential cytotoxic and inhibitory effects of titanium dioxide using on-line and non-invasive cell-based impedance spectroscopy.

Titanium dioxide (TiO2) nanoparticles (NPs) with different sizes and structures were probed for plausible cytotoxicity using electric cell-substrate impedance sensing (ECIS), a non-invasive and on-line procedure for continuous monitoring of cytotoxicity. For insect cells (Spodoptera frugiperda Sf9), the ECIS50 values, i.e.

Applications of functionalized and nanoparticle-modified nanocrystalline cellulose.

Nanocrystalline cellulose (NCC), a rod-shaped nanoscale material with exceptional strength and physicochemical properties, can be prepared from inexpensive renewable biomass. Besides its potential use as a reinforcing agent for industrial biocomposites, pristine NCC exhibits low toxicity and poses no serious environmental concerns, providing impetus for its use in bioapplications. Here, we review recent developments in the use of modified NCC for emerging bioapplications, specifically enzyme immobilization, antimicrobial and medical materials, green catalysis, biosensing and controlled drug delivery.

Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge.

NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sf9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS(50)), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines.

Synthesis of furfural from xylose by heterogeneous and reusable nafion catalysts.

Nafion 117 has been proven as a robust and reusable heterogeneous catalyst for the dehydration of 9.1 % (w/w) xylose in dimethyl sulfoxide (DMSO) to yield 60 % furfural in 2 h at 150 °C. The catalytic high activity promoted shorter reaction times to limit the formation of side-products which otherwise would lead to decreased yields.

Synthesis and characterization of an oligomeric conjugated metal-containing poly(p-phenylenevinylene) analogue.

A new nickel-containing bis(bromobenzyl)salphen monomer suitable for Gilch polymerization was prepared. Reaction with KO(t)Bu in THF-DMF afforded primarily gels, but also soluble, conjugated oligomers that are red-shifted in the absorption spectrum when compared to the monomer. This spectral change, consistent with an enhanced conjugation length, was also compared with a suitable model compound for the polymer.

Bimetallic Schiff base complexes: models for conjugated shape-persistent metallopolymers.

New Schiff base ligands with two metal binding sites have been prepared. Copper and zinc complexes of the ligands, which serve as models for rigid, conjugated metallopolymers, were synthesized and characterized. The copper complexes display only weak intramolecular antiferromagnetic interactions, suggesting that the polymer structure is not useful for developing magnetic materials.

Tetraalkoxyphenanthrene: a new precursor for luminescent conjugated polymers.

[reaction: see text] We have developed a convenient synthesis of tetraalkoxyphenanthrene derivatives and demonstrated their use to form luminescent conjugated oligomers and polymers. Palladium-catalyzed cross-coupling reactions of 2,7-diiodo-3,6-dimethoxy-9,10-di(2-ethylhexyloxy)phenanthrene produced high molecular weight poly(p-phenylene ethynylene)s and low molecular weight poly(p-phenylene vinylene)s. These new polymers, which are luminescent in the solid state and in solution, may be useful for developing LED or solar cell devices, or in chemical sensors.