Laboratoire P.A.S.T.E.U.R

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Magnetic actuation of discrete liquid entities with a deformable paramagnetic liquid substrate

Angewandte Chemie (2017) 

 

Because miniaturization is accompanied by an increase in the surface-over-volume ratio, most strategies for controlled manipulation of small-sized drops on substrates have relied on exploiting interfacial energy gradients, making it possible to actuate drops with various stimuli, including electrical or optical ones, but requiring adequate stimulus-responsive systems. In contrast, magnetic actuation of deposited drops has mainly relied on volume forces exerted on the liquid to be transported, which is poorly efficient with conventional diamagnetic liquids such as water or oil, unless magnetosensitive particles are added. Here, we describe a new way to magnetically control the motion of discrete liquid entities, in an additive-free and surface tension-independent manner. Our strategy consists of using a paramagnetic liquid as a deformable substrate to direct, using a magnet, the motion of various floating liquid entities, ranging from naked drops to liquid marbles. We demonstrate that, in our configuration, it is the substrate deformation that mainly dictates the behaviour of the floating liquid entity. We show that a broad variety of liquids, including diamagnetic (water, oil) and nonmagnetic ones can be efficiently transported using the moderate magnetic field (≈ 50 mT) produced by a cost-effective, cmsized permanent magnet. Complex trajectories can be achieved in a reliable manner and multiplexing potential is demonstrated through on-demand drop fusion. Our paramagnetofluidic method advantageously works without any complex equipment nor electric power, in phase with the necessary development of robust and lowcost analytical and diagnostic fluidic devices.

Human Pluripotent Stem Cell-Derived Cardiac Tissue-like Constructs for Repairing the Infarcted Myocardium

Stem Cell Reports, 2017, 9, 1546–1559

 

High-purity cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are promising for drug development and myocardial regeneration. However, most hiPSC-derived CMs morphologically and functionally resemble immature rather than adult CMs, which could hamper their application. Here, we obtained high-quality cardiac tissue-like constructs (CTLCs) by cultivating hiPSC-CMs on low-thickness aligned nanofibers made of biodegradable poly(D,L-lactic-co-glycolic acid) polymer. We show that multilayered and elongated CMs could be organized at high density along aligned nanofibers in a simple one-step seeding process, resulting in upregulated cardiac biomarkers and enhanced cardiac functions. When used for drug assessment, CTLCs were much more robust than the 2D conventional control.We also demonstrated the potential of CTLCs for modeling engraftments in vitro and treating myocardial infarction in vivo. Thus, we established a handy framework for cardiac tissue engineering, which holds high potential for pharmaceutical and clinical applications.

 

Copper-Catalyzed Hydroamination of Allenes: from Mechanistic Understanding to Methodology Development

ACS Catalysis2017, 7 (7), pp 4253–4264

Experimental and theoretical mechanistic studies on the Cu(OTf)2-catalyzed hydroamination reaction of terminal allenes with secondary amines reveal that in-situ generated cationic Cu(I) is the catalytically active species and explain the observed regio- and stereoselectivity for the unbranched E product. Insight about the structure of the relevant transition states allowed the generalization of this methodology to allenamides and N-allenylcarbamates under unprecedentedly mild and functional group tolerant conditions. Chelation effect by the amide oxygen in addition to electronic effects explain the high innate reactivity of this class of substrates.

New avenues for the large-scale harvesting of blue energy

Nature Reviews Chemistry 1, Article number: 0091 (2017)

 

Salinity gradients have been identified as promising clean, renewable and non intermittent sources of energy — so-called blue energy. However, the low efficiency of current harvesting technologies is a major limitation for large-scale viability and is mostly due to the low performances of the membrane processes currently in use. Advances in materials fabrication with dedicated chemical properties can resolve this bottleneck and lead to a new class of membranes for blue-energy conversion. In this Perspective, we briefly present current technologies for the conversion of blue energy, describe their performances and note their limitations. We then discuss new avenues for the development of a new class of membranes, combining considerations in nanoscale fluid dynamics and surface chemistry. Finally, we discuss how new functionalities originating from the exotic behaviour of fluids in the nanoscale regime can further boost energy conversion, making osmotic energy a tangible, clean alternative.

Forced intrusion of water and aqueous solutions in microporous materials: from fundamental thermodynamics to energy storage devices

Chem. Soc. Rev., 8, 2017

 

We review the high pressure forced intrusion studies of water in hydrophobic microporous materials such as zeolites and MOFs, a field of research that has emerged some 15 years ago and is now very active. Many of these studies are aimed at investigating the possibility of using these systems as energy storage devices. A series of all-silica zeolites (zeosil) frameworks were found suitable for reversible energy storage because of their stability with respect to hydrolysis after several water intrusion–extrusion cycles. Several microporous hydrophobic zeolite imidazolate frameworks (ZIFs) also happen to be quite stable and resistant towards hydrolysis and thus seem very promising for energy storage applications. Replacing pure water by electrolyte aqueous solutions enables to increase the stored energy by a factor close to 3, on account of the high pressure shift of the intrusion transition. In addition to the fact that aqueous solutions and microporous silica materials are environmental friendly, these systems are thus becoming increasingly interesting for the design of new energy storage devices.