Speakers:

Sifre VAN TEEFFELEN

Structural and thermodynamic effects of lipid hydroperoxidation in lipid bilayers

Lipid peroxidation is a defining feature of oxidative stress and a major factor in membrane dysfunction during aging, inflammation, and disease. While oxidation-induced changes in bilayer structure are well recognized (1), their impact on the main phase transition and membrane organization of phospholipids remains poorly understood (2). Here, we investigate how hydroperoxidation affects the phase behavior and structural properties of two phosphatidylcholine lipids, 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) and 1-stearoyl-2-petroselinoyl-sn-glycero-3-phosphocholine(SPPC), together with their hydroperoxidized forms.

Mixtures of oxidized and non-oxidized lipids were characterized using complementary techniques. Differential scanning calorimetry (DSC) and steady-state fluorescence spectroscopy with the environment-sensitive probes Laurdan (3) and A10 (4) were used to probe phase behavior. Membrane structure and organization were further investigated using neutron scattering. Hydroperoxidation strongly alters membrane thermodynamics and nanoscale structure, revealing a complex phase-transition landscape driven by acyl-chain ordering and hydroperoxide distribution (5). Together, these measurements provide a multiscale view of how lipid peroxidation modulates membrane organization, offering insight into the molecular consequences of oxidative stress in biomimetic membranes.

1. M. Páez Pérez, et al., Commun. Chem. 6, 15 (2023). DOI: 10.1038/s42004-022-00809-x

2. G. Wang, et al., J. Biol. Chem., 270, 22738–22746 (1995). DOI: 10.1074/jbc.270.39.22738 

3. T. Parasassi, et al., Biophys. J., 60, 179–189 (1991). DOI: 10.1016/S0006-3495(91)82041-0 

4. Z. Zheng, et al., RSC Adv. 6, 94200–94205 (2016). DOI: 10.1039/C6RA17438H

5. E. Lafarge, S. van Teeffelen, et al., J. Chem. Phys., 164, 185101 (2026). DOI: 10.1063/5.0323202 

Jeanne HERRY

Bottom-up Fabry-Pérot Chiral Cavities

Chiral Fabry-Pérot cavities can generate strong chiral electromagnetic intra-cavity fields, allowing the study of enhanced chiral light–matter interactions. Such cavities look particularly interesting in the context of light–matter strong coupling by giving the opportunity to form chiral polaritonic states with unique properties [1,2].  However to date, the design of such cavities has essentially remained theoretical.

Recently, using twisted anisotropic silver nanowires assemblies, prepared by grazing incidence spraying on a semi-reflective silver layer, chiral mirrors were fabricated. These bottom-up structures exhibit highly polarized reflectance over the UV, visible and near-IR range, with a preservation of the handedness of light upon reflection [3]. Therefore, the assembly of two such chiral mirrors facing each other is a promising approach for the creation of Fabry-Pérot cavities that can preserve one handedness of light in between the mirrors.

Such chiral cavities were built using different chiral configurations, with poly(methyl methacrylate) spin-coated in between as a tunable spacer. Their chiroptical properties were experimentally demonstrated using far-field Mueller Matrix polarimetry. These properties were also compared with Berreman-type transfer matrix simulations of the intracavity field profile with non-zero chiral densities. Our results demonstrate the relevance and promise of such Fabry-Perot cavities for future investigations in chiral polaritonics and chiral sensing.  

1. D. G. Baranov, C. Schäfer,  & M. V. Gorkunov, Toward Molecular Chiral Polaritons. ACS Photonics 10, 2440-2455 (2023)

2. K. Voronin, S. A. Taradin, M.V Gorkunov and D. G. Baranov, Single Handedness Chiral Optical Cavities, ACS Photonics, 9, 2652-2659, (2022)

3. W. Wu, Y. Battie, C. Genet, T. W. Ebbesen, G. Decher, and M. Pauly, Bottom-up tunable broadband semi-reflective chiral mirrors, Adv. Opt. Mat. 11, 2202831 (2023)