I. Dumbryte, D. Narbutis, M. Androulidaki, et al.

Correlative characterization of micro-scale defects in heterogeneous mineralized materials requires the spatial fusion of measurement modalities that differ in resolution, contrast mechanism, and coordinate system. This study presents a non-destructive multimodal measurement methodology in which X-ray micro-computed tomography (µCT) and spatially selective photoluminescence (PL) spectroscopy are linked on an intact specimen by a 3D surface mesh-assisted spatial registration framework, with complementary energy-dispersive X-ray spectroscopy (EDS) used to characterize the associated compositional changes. The registration aligns the volumetric and point-resolved measurements with a spatial uncertainty bounded by the PL laser spot size (diameter 80 µm) and the µCT voxel size (7 × 7 × 7 µm3), both smaller than the spacing between adjacent measurement points, ensuring well-defined co-localization of crack-affected and pristine regions. The methodology was demonstrated on extracted human premolars with visible enamel microcracks: 192 polarization-resolved PL spectra per tooth, acquired at 325 nm excitation across 12 spatial positions (6 cracked, 6 pristine) and spatially registered to the µCT datacube, revealed a reproducible difference in spectral shape between crack-affected and pristine regions. A peak asymmetry index, defined as the ratio of the two emission maxima, was reduced in cracked regions consistently in both teeth and significantly when pooled across specimens (1.16 vs 1.28; p = 0.014), supported by EDS evidence of increased carbon content at crack sites (a 42% relative increase in averaged carbon content, with the carbon-to-oxygen ratio rising from 0.46 to 0.84). The validated measurement framework — its spatial registration with bounded uncertainty — is material-independent and generalizable to correlative volumetric and spectroscopic defect characterization in heterogeneous solids.

D. Mehn, M. H. Silva, R. Verbeke, et al.

This study demonstrates the capability of analytical ultracentrifugation for assessing the morphological homogeneity of mRNA-lipid nanoparticles. Building on a standard method for density evaluation of nanoparticles, it demonstrates the importance of selecting the appropriate liquid medium for the experiments. Our research reveals the interaction between deuterated buffers and aqueous compartments of lipid-based particles. By investigating the sedimentation behavior of compact solid particles, liposomes, and lipid nanoparticles, we demonstrate that AUC can detect water-loaded cavities in mRNA-loaded lipid nanoparticles. Therefore, we suggest that performing sedimentation velocity experiments both in sucrose-containing buffer and deuterated solvents results in precious information not only on density but also on batch homogeneity and particle morphology.

F. Marabelli, G. Pellegrini, L. Zagaglia et al.

The interaction between light and chiral plasmonic metasurfaces provides a powerful mechanism for controlling polarization states at the nanoscale. Utilizing displacement Talbot lithography for large-area fabrication, we characterized the chiroptical response by measuring the evolution of Stokes parameters to quantify phase retardation between orthogonal polarization components. To elucidate the underlying physical mechanism, we employ a hybrid finite element method and rigorous coupled-wave analysis approach to investigate the behavior of the far-field and local-field configurations. Our results reveal that the phase shift is highly sensitive to symmetry-breaking features, where the interplay between different modes dictates the overall circular dichroism signal. Furthermore, the analysis of local field plots suggests specific contributions of plasmonic modes to the chiroptical response. We conclude that the phase shift effects, characterized via Stokes parameters and modal analysis, provide a robust metric for engineering chiroptical properties in these systems. This work establishes a fundamental framework for developing compact polarization-control elements and enhances the understanding of phase-modulated light-matter interactions in chiral plasmonic metasurfaces.