Ref HAL: hal-00777797_v1
DOI: 10.1007/s00726-011-975-2
Résumé: The reaction of cyanate with C-terminal carboxyl groups of peptides in aqueous solution was considered as a potential pathway for the abiotic formation of peptide bonds under the condition of the primitive Earth. The catalytic effect of dicarboxylic acids on cyanate hydrolysis was definitely attributed to intramolecular nucleophilic catalysis by the observation of the 1H-NMR signal of succinic anhydride when reacting succinic acid with KOCN in aqueous solution (pH 2.2-5.5). The formation of amide bonds was noticed when adding amino acids or amino acid derivatives into the solution. The reaction of N-acyl aspartic acid derivatives was observed to proceed similarly and the scope of the cyanate-promoted reaction was analyzed from the standpoint of prebiotic peptide formation. The role of cyanate in activating peptide C-terminus constitutes a proof of principle that intramolecular reactions of adducts of peptides C-terminal carboxyl groups with activating agents represent a pathway for peptide activation in aqueous solution, the relevance of which is discussed in connexion with the issue of the emergence of homochirality.

Ref HAL: hal-00777544_v1
DOI: 10.1016/j.tetlet.2012.03.082
Résumé: Lysine dendrigraft polymers (DGL) are promising candidates as carriers for targeted drug/gene delivery and bio-imaging, as such deserving extensive chemical functionalisation studies. We describe here examples of complete grafting of DGL amino groups by various substituents: hydrophobic amino acids (Ala, Val, Leu), dicarboxylic acids (succinic, Asp), guanidyl and saccharides (Gal), by means of straightforward coupling reactions, thus opening to versatile tuning of DGL properties (hydrophobicity, nucleophilicity, electric charge . . .). DGL functionalisation by lactose (when carried out so as to avoid borate ester formation between sugars) however yields partially grafted DGL; besides, partial grafting can be achieved by tuning the reagent/DGL stoichiometric ratio.

Ref HAL: hal-00777465_v1
DOI: 10.1021/ac300004t
Résumé: A new methodology for an antibacterial assay based on capillary electrophoresis with multiple UV detection points has been proposed. The possible antibacterial activity of cationic molecules on bacteria (Gram-positive and Gramnegative) is studied by detecting the bacteria before, during, and after their meeting with the cationic antibacterial compound. For that, a UV area imaging detector having two loops and three detection windows was used with a 95 cm ×100 μm i.d. capillary. In the antibacterial assay, the bacteria (negatively charged) and the cationic molecules were injected separately from each end of the capillary. The bacteria were mobilized by anionic ITP mode while cationic molecules migrate in the opposite direction under conditions close to CZE. The cationic molecules were injected into the capillary as a broad band (injected volume about 16% of the volume of the capillary) to prevent dilution of the sample during the electrophoretic process. Bacteriolytic activity, as well as strong interactions between the small antibacterial molecules and the bacteria, can be investigated within a few minutes. The assay was used to study the antibacterial activity of dendrigraft poly-L-lysines on Micrococcus luteus and Erwinia carotovora. Because dendrigraft poly-L-lysines are nonimmunogenic and have low toxicity, this new class of dendritic biomacromolecules is very promising for antibacterial applications.

Ref HAL: hal-00777255_v1
DOI: 10.1016/j.chroma.2012.03.095
Résumé: CompariThe purpose of this work was to compare single and double detection points Taylor Dispersion Analysis (TDA) of monodisperse and polydisperse samples for low injected volumes. For that, the hydrodynamic radii of human and bovine serum albumins, a poly(styrene sulfonate) standard and two dendrigraft polyl-lysines were determined by TDA on a capillary electrophoresis instrument using a modified detection interface allowing the analysis on two detection points. The results were compared to values obtained via a single detection point TDA with adequate corrections for the finite injected volume. The results showed no significant difference between the double and single detection points when Taylor conditions were respected and when the injected volume was less than 1% of the capillary volume till the detection window. The issue of the determination of the peak variance of the Taylorgram in the case of polydisperse sample with non-Gaussian peak is addressed. A criterion is proposed to define the interval of time on which thepeakvarianceiscalculatedbyintegrationasafunctionofthesignaltonoiseratio.

Ref HAL: hal-00777217_v1
DOI: 10.1016/j.chroma.2012.02.049
Résumé: This work describes a simple technical modification for doing Taylor dispersion analysis with two UV detection points on a commercial capillary electrophoresis apparatus. So far, double UV detection was only possible using specific detectors that are external to the capillary electrophoresis apparatus. In this work, the detection interface of the capillary electrophoresis apparatus was easily modified to allow the introduction and the superposition of two capillary windows in the same interface (at the same detection point). This modification made possible the double detection of the sample zone in Taylor dispersion analysis using a loop. The peak dispersion using the modified interface was similar to that obtained on a non-modified UV interface. Diffusion coefficients (and the corresponding hydrodynamic radii) of small molecule andproteinsweredeterminedingoodagreementwithvaluesoftheliteratureandwithRSD lower than 5%

Ref HAL: hal-00777202_v1
DOI: 10.1021/ac203208k
Résumé: The inline coupling of capillary electrophoresis (CE) to Taylor dispersion analysis was used for the characterization of polyelectrolyte complexes. The charge stoichiometry and the hydrodynamic radii of the two polyelectrolyte constituents were determined in a fully automated single run using standard commercial CE apparatus with a single detection point. The proposed methodology utilizes unusual high ionic strength (1.3 M) background electrolyte to obtain the dissociation and electrophoretic separation of polyelectrolyte constituents. Such highly saline conditions in combination with neutrally coated capillary were found to avoid any polyelectrolyte interactions onto the capillary surface. This innovative methodology should greatly contribute to simplify and accelerate the characterization of polyelectrolyte complexes or polyplexes.

Ref HAL: hal-00777009_v1
Résumé: Nanobiotechnology enables the emergence of entirely new classes of bioactive devices intended for targeted intracellular delivery for more efficacies and less toxicities. Among organic and inorganic approaches currently developed, controlled release from polymer matrices promises utmost clinical impact. Here, a unique nanotechnology strategy is used to entrap, protect, and stabilize therapeutic agents into polymer coatings acting as nanoreservoirs enrobing nanofibers of implantable membranes. Upon contact with cells, therapeutic agents become available through enzymatic degradation of the nanoreservoirs. As cells grow, divide, and infiltrate deeper into the porous membrane, they trigger slow and progressive release of therapeutic agents that, in turn, stimulate further cell proliferation. This constitutes the first instance of a smart living nanostructured hybrid membrane for regenerative medicine. The cell contact-dependent bioerodable nanoreservoirs described here will permit sustained release of drugs, genes, growth factors, etc., opening a general route to the design of sophisticated celltherapy implants capable of robust and durable regeneration of a broad variety of tissues.