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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., Bioimaging: Spotting viral signatures with ‘superchiral’ light A technique that uses twisted light fields to detect biomolecular structures could find application as a low-cost clinical tool for screening viruses. The protein coatings around many viruses, such as the turnip yellow mosaic virus (TYMV), have complex polyhedral shapes that are difficult to resolve with conventional optical microscopes. Malcolm Kadodwala from the University of Glasgow and other colleagues in the United Kingdom now report that ‘superchiral’ light — localized fields generated by metal nanostructures that spiral as they travel — are sensitive to the asymmetric polyhedral of TYMV. By spectroscopic measurements of particle rotations in superchiral light at different frequencies, the team identified specific asymmetric signals that correlated to virus alignment on gold photonic substrates. This approach was then used to determine TYMV levels in human blood serum spiked with the virus.

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.

This article belongs to the Special Issue Diet and Metabolic Dysfunction; International audience; Obesity and being overweight are linked with a cluster of metabolic and vascular disorders that have been termed the metabolic syndrome. This syndrome promotes the incidence of cardiovascular diseases that are an important public health problem because they represent a major cause of death worldwide. Whereas there is not a universally-accepted set of diagnostic criteria, most expert groups agree that this syndrome is defined by an endothelial dysfunction, an impaired insulin sensitivity and hyperglycemia, dyslipidemia, abdominal obesity and hypertension. Epidemiological studies suggest that the beneficial cardiovascular health effects of diets rich in green tea are, in part, mediated by their flavonoid content, with particular benefits provided by members of this family such as epigallocatechin gallate (EGCG). Although their bioavailability is discussed, various studies suggest that EGCG modulates cellular and molecular mechanisms of various symptoms leading to metabolic syndrome. Therefore, according to in vitro and in vivo model data, this review attempts to increase our understanding about the beneficial properties of EGCG to prevent metabolic syndrome.

Optical spectroscopic methods do not routinely provide information on higher order hierarchical structure (tertiary/quaternary) of biological macromolecules and assemblies. This necessitates the use of time-consuming and material intensive techniques, such as protein crystallography, NMR, and electron microscopy. Here we demonstrate a spectroscopic phenomenon, superchiral polarimetry, which can rapidly characterize ligand-induced changes in protein higher order (tertiary/quaternary) structure at the picogram level, which is undetectable using conventional CD spectroscopy. This is achieved by utilizing the enhanced sensitivity of superchiral evanescent fields to mesoscale chiral structure.

Obstructive Sleep Apnea Syndrome (OSAS) is defined by repetitive obstructions of upper airway during sleep inducing intermittent decrease in oxygen saturation or intermittent hypoxia (IH). IH alters endothelial function favoring inflammation and could accelerate atherosclerosis-induced cardiovascular diseases. A protein that may play a role in this process is the nonmuscular myosin light chain kinase (nmMLCK), protein involved in the regulation of endothelial permeability. The aim of this study was to analyze the implication of nmMLCK in inflammation induced by IH on endothelial cells. Human aortic endothelial cells (HAoECs) were exposed to 6h of IH, including 30min of hypoxia (O2 5%) followed by 30min of normoxia (O2 21%), in absence or presence of ML-7 (5μM), a nmMLCK inhibitor, and in absence or presence of interleukin-6 (IL-6, 40ng/ml), an inflammatory cytokine found in OSAS patients. After stimulation, we investigated inflammatory process by evaluating p65-NF-κB pathway and the release of several inflammatory cytokines by HAoECs. Activation of p65-NF-κB inflammatory pathway is increased in response to IH, as well as secretion of certain inflammatory cytokines such as IL-6 and CXCL-1 in HAoECs. While nmMLCK inhibition by ML-7 did not prevent p65-NF-κB activation, it partially decreased IL-6 and CXCL-1 secretion induced by IH. Moreover, to mimic the pro-inflammatory environment already established in OSAS patients, we costimulated HAoECs with IL-6 and IH. Under these conditions, IL-6 alone increased activation of STAT3 but did not potentiate the effects of IH regarding p65-NF-κB activation and cytokine secretion. These results suggest that nmMLCK may participate to the IH-induced inflammatory process in endothelial cells by modulating IH-induced cytokine secretion. Furthermore, IH is sufficient to induce inflammatory process independently of the proinflammatory environment. The author hereby declares no conflict of interest

A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case the scattering ratios between water and reference ν1 Q-branches were found to be 1.20 ± 0.03 and 0.40 ± 0.02 for H2 and CH4, respectively.

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