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Sensitivity of gold nanoparticles Second Harmonic scattering to surrounding medium change 
Auteur(s): Nadolski Krzysztof, Jonin C., Salmon Estelle, Behel Zacharie, Matczyszyn Katarzyna, Brevet Pierre-François
(Article) Publié:
Journal Of Molecular Liquids, vol. 388 p.122704 (2023)
Ref HAL: hal-04195211_v1
DOI: 10.1016/j.molliq.2023.122704
Exporter : BibTex | endNote
Résumé: Gold nanoparticles are widely used in sensing, notably in colorimetry-based methods, where a color change is associated to the Surface Plasmon Resonance peak shift due to a binding event or an environment modification in the vicinity of the nanoparticles. In this work, we explore the sensitivity of the Second Harmonic response from gold nanoparticles of two different diameters as this response stems principally from the nanoparticle surface at small sizes as opposed to the whole volume of the nanoparticle at larger sizes. The origin of this response is therefore different from that involved in the colorimetric response, the latter being of volume origin. Upon addition of Glycerol to an aqueous solution of nanoparticles, Surface Plasmon Resonance peak shifts are first observed but they cannot fully explain the Second Harmonic intensity changes recorded. Hence, in order to gain further insights into the origin of the changes observed in the experimental data, polarization-resolved Second Harmonic measurements are performed. A mechanism where first a modification of the first hyperpolarizability of the nanoparticles due to the presence of glycerol occurs followed by nanoparticle aggregation is then proposed. The potential alternative use of this nonlinear optical method of Second Harmonic scattering for sensing purposes is then discussed in light of a figure of merit proposed to describe the sensing sensitivity observed.
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Biomechanical characterization of a fibrinogen–blood hydrogel for human dental pulp regeneration
Auteur(s): Piglionico Sofia Silvia, Varga B., Pall Orsolya, Romieu Olivier, Gergely C., Cuisinier Frédéric, Levallois Bernard, Panayotov Ivan Vladislavov
(Article) Publié:
Biomaterials Science, vol. p. (2023)
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Organization of collagen fibers and tissue hardening: Markers of fibrotic scarring after spinal cord injury in mice revealed by multiphoton-atomic force microscopy imaging
Auteur(s): Manesco C., Saavedra O., Martin Fernandez M., De Lizaraga J., Varga B., Cloitre T., Gerber Yannick Nicolas, Perrin Florence Evelyne, Gergely C.
(Article) Publié:
Nanomedicine Nanotechnology, Biology And Medicine, vol. p.102699 (2023)
Ref HAL: hal-04195286_v1
DOI: 10.1016/j.nano.2023.102699
Exporter : BibTex | endNote
Résumé: Spinal cord injury is a dramatic disease leading to severe motor, sensitive and autonomic impairments. After injury the axonal regeneration is partly inhibited by the glial scar, acting as a physical and chemical barrier. The scarring process involves microglia, astrocytes and extracellular matrix components, such as collagen, con- structing the fibrotic component of the scar. To investigate the role of collagen, we used a multimodal label-free imaging approach combining multiphoton and atomic force microscopy. The second harmonic generation signal exhibited by fibrillar collagen enabled to specifically monitor it as a biomarker of the lesion. An increase in collagen density and the formation of more tortuous fibers over time after injury are observed. Nano-mechanical investigations revealed a noticeable hardening of the injured area, correlated with collagen fibers' formation. These observations indicate the concomitance of important structural and mechanical modifications during the fibrotic scar evolution.
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