Precise AuxPt1-x alloy nanoparticle array of tunable composition for catalytic applications

A 3-dimensional Block Copolymer Micellar nanoLithography (BCML) process was used to prepare AuxPt1-x alloy nanoparticles (NPs) monodisperse in size and composition, strongly anchored onto SiO2-particles (0.2 wt.% AuxPt1-x/SiO2). The particles possess a face-centered cubic (fcc) crystal structure and their size could be varied from 3-12 nm. We demonstrate the uniformity of the Au/Pt composition by analyzing individual NPs by energy-dispersive X-ray spectroscopy. The strongly bound AuxPt1-x NPs catalyzed the oxidation of CO with high activity. Thermal ageing experiments in pure CO2 as well as in ambient atmosphere demonstrated stability of the size distribution for times as long as 22 h

Exposure of the marine deposit feeder Hydrobia ulvae to sediment associated LAS

7 páginas, 4 figuras, 4 tablas.Linear Alkylbenzene Sulfonates (LAS) effects (mortality, egestion rate, behaviour) on the marine deposit feeder Hydrobia ulvae were assessed in whole-sediment and water-only systems. The results were combined with a bioenergetic-based kinetic model of exposure pathways to account for the observed toxicity. The 10-d LC50 value based on the freely dissolved fraction was 9.3 times lower in spiked sediment (0.152 ± 0.001 (95% CI) mg/L) than in water-only (1.390 ± 0.020 (95% CI) mg/L). Consequently, the actual 10-d LC50 value (208 mg/kg) was overestimated by the Equilibrium Partitioning calculation (1629 mg/kg). This suggests that the sediment associated LAS fraction was bioavailable to the snails. It could also be due to modifications in physiological parameters in absence of sediment, the organism natural substrate.This research was supported by the European Commission through the FP6 program (EST Marie Curie Fellowship) and it was performed in the framework of the RISICO project (MEST-CT-2004-505182). We also acknowledge the financial support of ERASM, ECOSOL and PETRESA.Peer reviewe

Synthesis of poly(lactide-co-glycolide-co-ε-caprolactone)-graft-mannosylated poly(ethylene oxide) copolymers by combination of “clip” and “click” chemistries

Poly(lactide-co-glycolide) (PLGA) is extensively used in pharmaceutical applications, for example, in targeted drug delivery, because of biocompatibility and degradation rate, which is easily tuned by the copolymer composition. Nevertheless, synthesis of sugar-labeled amphiphilic copolymers with a PLGA backbone is quite a challenge because of high sensitivity to hydrolytic degradation. This Article reports on the synthesis of a new amphiphilic copolymer of PLGA grafted by mannosylated poly(ethylene oxide) (PEO). A novel building block, that is, α-methoxy-ω-alkyne PEO-clip-N-hydroxysuccinimide (NHS) ester, was prepared on purpose by photoreaction of a diazirine containing molecular clip. This PEO block was mannosylated by reaction of the NHS ester groups with an aminated sugar, that is, 2-aminoethyl-α-d-mannopyroside. Then, the alkyne ω-end-group of PEO was involved in a copper alkyne- azide coupling (CuAAC) with the pendent azides of the aliphatic copolyester. The targeted mannose-labeled poly(lactide-co-glycolide-co-ε-caprolactone)-graft-poly(ethylene oxide) copolymer was accordingly formed. Copolymerization of d,l-lactide and glycolide with α-chloro-ε-caprolactone, followed by substitution of chlorides by azides provided the azido-functional PLGA backbone. Finally, micelles of the amphiphilic mannosylated graft copolymer were prepared in water, and their interaction with Concanavalin A (ConA), a glyco-receptor protein, was studied by quartz crystal microbalance. This study concluded to the prospect of using this novel bioconjugate in targeted drug delivery