The structural organization of collagen plays a crucial role in biological function and biomaterial design due to its characteristic triple-helical structure. Understanding its self-assembly under varying conditions is crucial for biomaterials and regenerative medicine applications. In this study, we employ Vibrational Sum Frequency Generation (VSFG) spectroscopy to investigate the self-assembly of collagen at different pH levels. We compare telocollagen, which retains telopeptides known to facilitate fibrillogenesis, with atelocollagen, which lacks these terminal peptides, therefore leading to more heterogeneous assembly.VSFG is a surface-sensitive technique that enables the analysis of structural changes at interfaces. Although collagen is usually considered a α-helical triple helix, our results reveal unexpected deviations of the 3D structure with the spectral signature of β-sheet formation, suggesting alternative secondary structures at interfaces that challenge the conventional α-helix model. Furthermore, the presence or absence of telopeptides not only influences the fibrillary arrangement but also alters the chiral organization of collagen. This study provides new insights into the molecular mechanisms governing collagen self-assembly, the role of telopeptides and pH modulating both chirality and secondary structure.

Dental pulp is a soft, complex tissue found inside the tooth root, made up of cells, blood vessels, and an extracellular matrix filled with organized fibers. This study explores the use of Broadband Coherent Anti-Stokes Raman Scattering (BCARS) microscopy to enhance chemical contrast, helping to better characterize dental pulp and analyze the unique spectral signatures of its individual cells. To obtain samples, pulp was extracted from the third molars of healthy patients. After removing the tooth crown, the pulp was carefully taken out and fixed in 4% paraformaldehyde (PFA). The samples were then embedded in paraffin, cut into ultra-thin 3 μm sections using a Microm HM340E with a Niagara system, and dewaxed with xylene to prepare for imaging. BCARS microscopy was performed using a Piezo X,Y,Z scanner (Nano-LP300, MCL), with imaging controlled through LabView software. Spectral data was extracted from raw BCARS signals using TDKK, a Python-based software (Crikit2, available on GitHub by C. Camp). The Raman spectral images covered a broad range (500–3800 cm⁻¹), capturing signals from weakly scattering modes and C-H vibrations. Spectral analysis revealed specific peaks linked to blood vessels (1651 cm⁻¹, 1440 cm⁻¹), as well as molecular signatures of lipids, proteins, phenylalanine, and nucleic acids in cells. Structural fibers such as elastin and collagen were also identified. These findings demonstrate that BCARS microscopy is a powerful tool for generating detailed chemical images of dental pulp, offering a deeper understanding of its composition and structure. By distinguishing various molecular components, this technique presents exciting possibilities for advanced tissue analysis in dentistry.

Second Harmonic Scattering is the incoherent second order light scattering occuring in isotropic bulk solutions due to the molecular orientation. It is an efficient technique to determine the molecular second order polarizability of solute molecules. The measurement of the bacteriorhodopsin protein hyperpolarizability has opened the way to the determination of the non linear response of biomolecules. Since then, many different proteins have been investigated.In addition to their technological promess, the biological and chemical properties of DNA, and the almost infinite variety of structures that can be obtained, the DNA structures are considering for many applications, in biology and biophysics, to study biomaterials and reproduce cellular behaviors, but also in optoelectronics, to modify optical properties of surfaces, or finally as micrometric molecular motors.DNA nucleotides, are demonstrating to be versatile materials in natural electronics and photonics, a very promising field of research in which biological materials are employed to build environmentally friendly microelectronic and optoelectronic devices.It has to be noted that there are much fewer reports describing the use of nucleobases in bioelectronics than for DNA. The measurements of the first hyperpolarizability allow for the characterization of the solute quadratic optical nonlinear response can yield information about the macromolecular conformation in solution. Particularly, the angular dependence of the HRS intensity allowed to unravel further information on the nonlinear response symmetry.Beyond nucleotides, many of non-canonical DNA structures have shown their involvement in diseases like cancer and genetic disorders remain of interest and the present work constitutes a first step into this direction.Hence, we present the studies of biological materials in reporting the measurement of the first hyperpolarizability of the four DNA nucleotides and compare them to the results of DFT calculations. A polarization analysis of the HRS intensity was also performed to question the symmetry of the first hyperpolarizability tensor.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of upper and lower motor neurons, leading to severe muscle atrophy and functional impairment. ALS has an incidence of approximately 1 to 2 cases per 100,000 individuals per year, with most cases being sporadic (90–95%) and a smaller percentage linked to genetic mutations, including SOD1. The disease predominantly affects individuals between the ages of 50 and 70, progressing rapidly with a median survival of 2 to 5 years post-diagnosis. Despite extensive research on motor neuron degeneration, the impact of ALS on skeletal muscle at the microscopic scale remains insufficiently explored.This study aimed to characterize structural alterations in skeletal muscle fibers of an ALS mouse model (SOD1-G93A) using second harmonic generation (SHG) multiphoton microscopy and atomic force microscopy (AFM). SHG imaging was employed to assess sarcomere periodicity and orientation. In particular, the latter parameter was analyzed using the CAS3D technique, revealing significant differences between WT and SOD1-G93A mice. AFM provided morphological insights into sarcomere organization by analyzing the length of the A and I band within gastrocnemius muscle sarcomeres. The results demonstrated significant differences between ALS-affected and control fibers:for the A band, a mean length value of 1.514 µm for the WT and 1.216 µm for the SOD1-G93A were measured, while for the I band, we calculated a mean length value of 0.5652 µm for the WT and 0.4970 µm for the SOD1-G93A (N = 3, n = 76). These nanoscale disruptions further underline the structural impairment in pathological skeletal muscle. Overall, SHG analysis demonstrated a significant reduction in sarcomere periodicity in SOD1-G93A mice compared to WT controls, indicating structural dysregulation at the sarcomeric level. AFM analysis demonstrated nanoscale alterations in sarcomeric bands. These findings highlight significant structural and mechanical modifications in ALS-affected skeletal muscle, contributing to a deeper understanding of ALS muscle pathology. This work underscores the potential for novel diagnostic and therapeutic approaches targeting muscle integrity in neurodegenerative diseases.

Collagen is a key protein in mammals maintaining structural integrity within tissues. A failure in fibrillar collagen reorganization may induce cancer or fibrosis formation, such as in spinal cord injury (SCI), where the healing process after the initial trauma leads to the formation of scar tissue, which includes fibrosis. There is no current treatment targeting the fibrotic process directly, thus a better understanding of collagen properties can help to apprehend malignant states. Characterization of collagen fibers has been widely explored on second-harmonic generation (SHG) images, due to the label-free nature of the SHG imaging technique. Various fibers’ extraction methods have been performed such as curvelet transform (CT) implemented in the open-source software CurveAlign. However, when it comes to investigating collagen fibers that are still under reorganization – undergrowth fibers – as observed in SCI, the CT method becomes complex to tune for non-advanced users in order to properly segment the fibers. To improve collagen detection in the case of undergrowth fibers, we propose a methodology based on the fingerprint enhancement (FP-E) algorithm that requires fewer user input parameters and is less time-consuming. Our method was extensively tested on SHG data from injured spinal cord samples. We obtained metrics that depicted changes in collagen organization over time, particularly a significant increase in fiber density, demonstrating the FP-E algorithm was properly adapted to extract the fibers and was a promising tool to address the evolution of collagen properties after SCI. Besides, the tuning of the method is simpler compared to commonly used software, and the combination with further characterization of the extracted fibers could lead to consider fibrillar collagen as a biomarker in diseases where fibers are under development.

The “Plastics, Environment and Health” research network (groupement de recherche, GDR) created in 2019 gathers the French scientific community working on plastic pollution in all environments (soil, air, water) and their impact on ecosystems and human health. The scientific objective is to rapidly increase knowledge on plastic pollution by supporting collaboration of researchers from different fields such as ecotoxicology, chemistry, physics, microbiology, oceanography and social science. Research is carried out at each stage of the plastic life cycle, (from resource extraction all the way to removal and remediation) and across the entire air-soil-water continuum, integrating transfers of both plastic particles (macro, micro- and nanoplastics) and plastic chemicals (e.g., additives) between different environmental compartments. In this context, the GDR supports the development of multi-scale and transdisciplinary approaches across three main axes: Axis 1 - Air-soil-water continuum: contamination levels and transfer between compartments; Axis 2 - Interactions and transformation of plastics in environmental compartments and living organisms; Axis 3. Plastic pollution risk assessment for ecosystems and human health. To do so, the GDR’s actions focus on (1) training and sharing of scientific knowledge, including developments towards innovation, (2) support for collaboration and interdisciplinarity between network members, (3) dissemination, structuring of the community and its national and international influence, and (4) support for public policy and/or decision-making by strengthening the link between scientists, decision-makers and the plastic industry. To date the research network includes more than 50 laboratories spread across France and over 300 scientists in the field of physics, chemistry, biology, ecology and social sciences. Such a network constitutes a powerful tool to build robust science-based knowledge significantly contributing to the international effort, to disseminate state-of-the-art scientific advances and research priorities needed to tackle plastic pollution to Society and to inform policy makers. This talk will present the French taskforce addressing 'Plastic, Environment, and Health' within the national research network, where the entire community works collaboratively to tackle the urgent challenges of plastic pollution, its environmental consequences, and the associated risks to human health. We will also discuss the importance of building a French-speaking community to support multilingualism in international political science interactions.

We present a scalable solution-processing method for fabricating high-quality graphene and graphene/1T-MoS2 heterostructure films. The process begins with the synthesis of potassiumintercalated graphite (KC8), which is exfoliated in tetrahydrofuran (THF) to produce stable dispersions of negatively charged (electron rich) graphene sheets. The graphene is subsequently transferred to water, forming a surfactant-free aqueous dispersion suitable for creating homogenous graphene films via vacuum filtration and stamping. Additionally, graphene is combined with 1T-MoS2 nanosheets to fabricate graphene/1T-MoS2 bulk heterostructure films. Comprehensive characterization, including X-ray diffraction (XRD), absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photon emission spectroscopy (XPS), reveals that the heterostructure films exhibit enhanced optical and electronic properties, including improved light absorption, which could lead to novel photo-responsive devices. Raman spectroscopy shows significant changes in the graphene's structural and electronic properties upon interaction with MoS2, indicating strong interlayer coupling and potential charge transfer between the layered components. The graphene films demonstrate highly sensitive detection of dopamine (DA), while the graphene/1T-MoS2 bulk heterostructure films exhibit capacitance values up to 38.3

Fg -1 at 5 mV s -1 in non-aqueous electrolytes. These results highlight the potential of these films for advanced applications in molecular sensing and energy storage.