Biomacromolecular charge chirality detected using chiral plasmonic nanostructures

The charge distributions of solvent exposed surfaces of complex biomolecules such has proteins are unique fingerprints. The chirality of these charge distributions result in stereo-specific electrostatic interactions which help define how proteins interact with each other, contributing to specificity in protein – protein interactions. Thus it is a key concept in understanding chemical processes in biology. There is currently no known spectroscopic phenomenon that allows rapid characterisation of chiral surface charge distributions. We show that this essential property that is currently “invisible” to optical spectroscopy, can be detected by monitoring asymmetries in the chiroptical response of protein-plasmonic nanostructure complexes. The unique capabilities of the phenomenon are utilised to discriminate between a structurally homologous series of proteins, type II dehydroquinase (DHQase) derived from different organisms. The proteins are indistinguishable with conventional structurally sensitive spectroscopy (i.e. circular dichroism). We show that discrimination between proteins can be achieved by detecting differences in chiral surface charge distributions. The phenomenon is explained with a simple model whereby the chiroptical properties of the plasmonic structures are perturbed by the induction of an enantiomeric mirror image charge distribution of the protein in the metal. This new phenomenon has broad impact, it is a powerful analytical tool for discriminating between structurally homologous biomaterials, but will also provide information relevant to macromolecular interactions

Probing specificity of protein-protein interactions with chiral plasmonic nanostructures

Protein–protein interactions (PPIs) play a pivotal role in many biological processes. Discriminating functionally important well-defined protein–protein complexes formed by specific interactions from random aggregates produced by nonspecific interactions is therefore a critical capability. While there are many techniques which enable rapid screening of binding affinities in PPIs, there is no generic spectroscopic phenomenon which provides rapid characterization of the structure of protein–protein complexes. In this study we show that chiral plasmonic fields probe the structural order and hence the level of PPI specificity in a model antibody–antigen system. Using surface-immobilized Fab′ fragments of polyclonal rabbit IgG antibodies with high specificity for bovine serum albumin (BSA), we show that chiral plasmonic fields can discriminate between a structurally anisotropic ensemble of BSA-Fab′ complexes and random ovalbumin (OVA)-Fab′ aggregates, demonstrating their potential as the basis of a useful proteomic technology for the initial rapid high-throughput screening of PPIs

Superchiral near fields detect virus structure

Optical spectroscopy can be used to quickly characterise the structural properties of individual molecules. However, it cannot be applied to biological assemblies because light is generally blind to the spatial distribution of the component molecules. This insensitivity arises from the mismatch in length scales between the assemblies (a few tens of nm) and the wavelength of light required to excite chromophores (≥150 nm). Consequently, with conventional spectroscopy, ordered assemblies, such as the icosahedral capsids of viruses, appear to be indistinguishable isotropic spherical objects. This limits potential routes to rapid high-throughput portable detection appropriate for point-of-care diagnostics. Here, we demonstrate that chiral electromagnetic (EM) near fields, which have both enhanced chiral asymmetry (referred to as superchirality) and subwavelength spatial localisation (∼10 nm), can detect the icosahedral structure of virus capsids. Thus, they can detect both the presence and relative orientation of a bound virus capsid. To illustrate the potential uses of the exquisite structural sensitivity of subwavelength superchiral fields, we have used them to successfully detect virus particles in the complex milieu of blood serum

Phase Behaviour and Morphology of a High Hard Block Content Polyurethane

International audienc

Enthalpy of solution and solubility of CO2 in aqueous alkanolamine solutions

Poster communicatio

Enthalpy of solution of CO2 in aqueous solutions of 2-amino-2-methyl-1-propanol

International audienc

Influence of amine structure on CO2 absorption properties: thermodynamic approach

International audienc

Enthalpy of absorption and limit of solubility of CO2 in aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol, 2-[2-(dimethyl-amino)ethoxy] ethanol and 3-dimethyl-amino-1-propanol at T = 313.15 K and 353.15 K and pressures up to 2 MPa.

International audienceIn order to study the influence of amine structure on absorption of carbon dioxide, enthalpies of solution of CO2 in 2.50 mol.L-1 aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol (THAM), 2-[2-(dimethyl-amino)ethoxy] ethanol (DMAEOE) and 3-dimethyl-amino-1-propanol (DMAP) were measured. The enthalpies of solution are determined as function of gas loading charge (moles of CO2/mole of amine), at temperatures 313.15 K and 353.15 K, and pressures range from 0.5 MPa to 2 MPa. Measurements are carried out using a flow calorimetric technique. CO2 solubilities in the aqueous solutions of amine are derived from calorimetric data. Molar volumes of aqueous amine solutions required to handle calorimetric data were determined at 303.15 K using a vibrating tube densimeter. Experimental enthalpies of solution are discussed on the basis of amines alkalinity

Etudes thermodynamiques des systèmes Eau /DEA /TDG + CO2 et Eau /DEA /TDG + H2S à 40°C, 80°C et 120°C.

nombre de pages : 90Rapport confidentiel Caractérisation d'absorbants pour le captage de CO2 et H2