Preventing corona effects: multi-phosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles

When disperse in biological fluids, engineered nanoparticles are selectively coated with proteins, resulting in the formation of a protein corona. It is suggested that the protein corona is critical in regulating the conditions of entry into the cytoplasm of living cells. Recent reports describe this phenomenon as ubiquitous and independent of the nature of the particle. For nanomedicine applications however, there is a need to design advanced and cost-effective coatings that are resistant to protein adsorption and that increase the biodistribution in vivo. In this study, phosphonic acid poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide particles. The copolymer composition was optimized to provide simple and scalable protocols as well as long-term stability in culture media. It is shown that polymers with multiple phosphonic acid functionalities and PEG chains outperform other types of coating, including ligands, polyelectrolytes and carboxylic acid functionalized PEG. PEGylated particles exhibit moreover exceptional low cellular uptake, of the order of 100 femtograms of iron per cell. The present approach demonstrates that the surface chemistry of engineered particles is a key parameter in the interactions with cells. It also opens up new avenues for the efficient functionalization of inorganic surfaces.Comment: 21 page, 7 figures,Biomacromolecules 201

Piezo-force and vibration analysis of ZnO nanowire arrays for sensor application

To estimate the potential of ZnO nanostructures for force sensing applications, arrays of single nanowires and arrays of nanowire bundles have been fabricated by wet chemical growth method. The piezoelectrical and electrical properties of the single nanowires have been investigated by atomic force microscopy based techniques. The piezoelectric constant d(33) = 15 pm/V has been determined from vibration analyses. The electrical response in the range up to 400 fA upon applying force between 40 nN and 1 mu N has been recorded. The nanowire bundles were studied by electro-mechanical macro probing technique within the force range 1 - 10 mN, where a reproducible response in pA range has been measured

''Type 2 diabetes in the elderly, which specific features?''

Graillot, D. | Quipourt, V. | Bouillet, B. | Petit, J. -M. | Manckoundia, P.International audience''Type 2 diabetes, whose prevalence has increased among elderly aged over 75 years, has a number of specific features which differ from that in young people: heterogeneous population, association with other cardiovascular risk factors and several comorbidities, different therapeutic constraints and risks, and lower life expectancy. By using a standardized geriatric assessment it is possible to determine therapeutic and glycemic goals for each patient. In the elderly, main complications of diabetes are hypoglycemia and foot lesions. In order to avoid malnutrition, lifestyle and dietary rules should not be too strict. Recommendations for the prescription of oral antidiabetic agents are the same for both elderly and young subjects, but with increased monitoring in the elderly because of the high risk of complications including iatrogenic hypoglycemia. Insulin therapy should be preferred. (C) 2012 Societe nationale francaise de medecine interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.'

Hydrological mass balance of boreal watersheds in the Canadian Shield

International audienceThis study aims at evaluating the hydrological balance of large watersheds of the Canadian Shield in the James Bay area in Northwestern Quebec, Canada. The focus is set on six rivers of the Canadian Shield altogether draining more than 185,000 km2 of the Boreal Shield, Taiga Shield and Hudson Plains ecozones of Canada. River discharge measurements, geochemical data (δ2H, δ18O and electrical conductivity [EC] of water), remote sensing, and GIS models are used jointly to calculate water balances. The approach allows for partitioning the influence of rainwater, snowmelt, surface runoff, evaporation, transpiration, and groundwater discharge to the hydrological balances of watersheds. On an annual basis, the results suggest that runoff from rainwater (30–61 % of total precipitation) and snowmelt (18–40 % of total precipitation) are the main contributions to river discharge, while the contribution of groundwater discharge to rivers represents 3 of water. The stable isotope mass balances allow for estimating watershed-scale evaporation over inflow ratios ranging between 2 and 10 % and suggest that transpiration has an isotopic composition close to summer rainwater. The hydrological balances further suggest that the total pool of water stored in the active portion of watersheds represents 10–20 % of the total annual precipitation, while the exports of groundwater beyond the limits of surface watersheds are negligible. The seasonal trends in the hydrological balances of monitored watersheds were further documented to provide insights into the sensitivity of watersheds as they face climate change. The observations are used to propose recommendations for monitoring of rivers in the Canadian Shield and to identify future research needs

Piezo-force and vibration analysis of ZnO nanowire arrays for sensor application

To estimate the potential of ZnO nanostructures for force sensing applications, arrays of single nanowires and arrays of nanowire bundles have been fabricated by wet chemical growth method. The piezoelectrical and electrical properties of the single nanowires have been investigated by atomic force microscopy based techniques. The piezoelectric constant d33 = 15 pm/V has been determined from vibration analyses. The electrical response in the range up to 400 fA upon applying force between 40 nN and 1 μN has been recorded. The nanowire bundles were studied by electro-mechanical macro probing technique within the force range 1 - 10 mN, where a reproducible response in pA range has been measured

UV-crosslinked polymeric materials for encapsulation of ZnO nanowires in piezoelectric fingerprint sensors

The work presented here describes new UV-crosslinkable thin layer polymeric materials for the encapsulation of ZnO nanowires (NWs) in multi-NWs pressure based fingerprint sensors. Such innovative sensor is a novel technology for fingerprint capture developed within the PiezoMAT FP7 European project. The sensing principle is based on the piezoelectric property of ZnO NWs, on which a potential difference is generated when they undergo compression and/or bending forces. Since the pressure induced by the finger cannot be directly applied on the NWs, the deformation is applied through a polymeric material that aims at transferring forces from the finger onto the array of NWs without altering their integrity. Besides, since it is dedicated to be in direct contact with human finger or oil pollutants, the encapsulation layer must also exhibit chemical inertness, as well as hydrophobicity and oleophobicity

Multidisciplinary diagnostic to characterize river/karst exchanges

International audienc