Search

Photothermoresponsive polymer brushes were synthesized by coupling azobenzene derivatives to oligo(ethylene glycol) methacrylate (OEGMA) based copolymer brushes grown from silicon substrates. Varying the length and chemical ending of the lateral chains (using different OEGMA comonomers) afforded a collection of thermoresponsive copolymer brushes with predetermined fraction of hydroxyl side groups. These pendent hydroxyl functions were subsequently used to anchor the photochromic modules onto the brushes via classical activation/coupling chemistry, albeit in modest to moderate yields depending on the brush composition, thickness and grafting density. The extent of swelling of the functionalized brushes in water could be reversibly modulated by photoisomerization of the azobenzene motifs, even though the amplitude of the observed variation remained small. Decreasing the grafting density of the brush afforded improved photoresponse possibly through decreased steric crowding between the chains, facilitating a...

International audience; A new binuclear Cu(II) complex derived from a pamoic type ligand has been synthesized and characterized by X-ray crystallography. This complex was checked as catalysts in the hydrolysis of bis(p-nitro-phenyl)phosphate. Its catalytic properties were studied at various pH and compared to the mononuclear Cu(II) complex. At pH 5.38, the binuclear Cu(II) complex exhibited a phosphatase-like activity with 11 TON and 24% conversion and was found to be 41-fold more active than the mononuclear counterpart.

There is an increasing demand for the development of sensitive enzymatic assays compatible with droplet-based microfluidics. Here we describe an original strategy, activity-fed translation (AFT), based on the coupling of enzymatic activity to in vitro translation of a fluorescent protein. We show that methionine release upon the hydrolysis of phenylacetylmethionine by penicillin acylase enabled in vitro expression of green fluorescent protein. An autocatalytic setup where both proteins are expressed makes the assay highly sensitive, as fluorescence was detected in droplets containing single PAC genes. Adding a PCR step in the droplets prior to the assay increased the sensitivity further. The strategy is potentially applicable for any activity that can be coupled to the production of an amino acid, and as the microdroplet volume is small the use of costly reagents such as in vitro expression mixtures is not limiting for high-throughput screening projects.

Under hypoxia, cancer cells consume glucose and release lactate at a high rate. Lactate was recently documented to be recaptured by oxygenated cancer cells to fuel the TCA cycle and thereby to support tumor growth. Monocarboxylate transporters (MCT) are the main lactate carriers and therefore represent potential therapeutic targets to limit cancer progression. In this study, we have developed and implemented a stepwise in vitro screening procedure on human cancer cells to identify new potent MCT inhibitors. Various 7-substituted carboxycoumarins and quinolinone derivatives were synthesized and pharmacologically evaluated. Most active compounds were obtained using a palladium-catalyzed Buchwald-Hartwig type coupling reaction, which proved to be a quick and efficient method to obtain aminocarboxycoumarin derivatives. Inhibition of lactate flux revealed that the most active compound 19 (IC 50 11 nM) was three log orders more active than the CHC reference compound. Comparison with warfarin, a conventional anticoagulant coumarin, further showed that compound 19 did not influence the prothrombin time which, together with a good in vitro ADME profile, supports the potential of this new family of compounds to act as anticancer drugs through inhibition of lactate flux. © 2013 Elsevier Ltd. All rights reserved.

Droplet-based microfluidics is a powerful tool for biology and chemistry as it allows the production and the manipulation of picoliter-size droplets acting as individual reactors. In this format, high-sensitivity assays are typically based on fluorescence, so fluorophore exchange between droplets must be avoided. Fluorogenic substrates based on the coumarin leaving group are widely used to measure a variety of enzymatic activities, but their application in droplet-based microfluidic systems is severely impaired by the fast transport of the fluorescent product between compartments. Here we report the synthesis of new amidase fluorogenic substrates based on 7-aminocoumarin-4-methanesulfonic acid (ACMS), a highly water-soluble dye, and their suitability for droplet-based microfluidics applications. Both substrate and product had the required spectral characteristics and remained confined in droplets from hours to days. As a model experiment, a phenylacetylated ACMS was synthesized and used as a fluorogenic substrate of Escherichia coli penicillin G acylase. Kinetic parameters (k(cat) and K(M)) measured in bulk and in droplets on-chip were very similar, demonstrating the suitability of this synthesis strategy to produce a variety of ACMS-based substrates for assaying amidase activities both in microtiter plate and droplet-based microfluidic formats.