Biophotonics

The BioPhotonics team conducts research located at the interface between physics and life sciences. Our experimental physical approach to study complex biological systems is based on monitoring interaction of light with biological material through microscopic and spectroscopic techniques.

We develop and employ various (non)linear photonic and biomechanical approaches for applications in life sciences to study molecular assemblies, living cells and tissues. The group holds its own « BioImaging » user facility comporting the following technologies: Optical-fluorescence microscope, Atomic Force Microscopy, Multiphoton microscopy in two-photon excited and second harmonic generation modes, Broadband Coherent Raman Spectroscopy imaging, and Second Harmonic Scattering (SHS) spectroscopy. Our multimodal approach enables measuring relevant physical (non-linear optics and nanomechanical) signals underlying various pathologies to support with new knowledge and better understand the biological modifications, the objective being to assess the relevant structural, morphological and spectral signature as well as the biomechanical behavior of diseased versus healthy tissues, cells or biofluids.

By multiphoton microscopy imaging we monitor in a label-free manner the non-linear optical response (two-photon excited fluorescence and second harmonic generation) of biomolecular systems like collagen, microtubules, myofibrils, sarcomeres in very varied biological structures such as cancerous cells, cardiomyocytes, stem cells, excised spinal cord, muscle or cardiac tissues. SHG signal analysis and processing algorithms developed in our laboratory are used to compute and quantify density, length, tortuosity and orientation of myofibrils, sarcomeres and collagen fibers.

Second Harmonic Scattering (SHS) spectroscopy is used to investigate the nonlinear response of (bio-)molecular systems like collagen, DNA bases in a liquid environment. Information on the molecular structure and symmetry can be obtained by polarization-resolved SHS experiments.

For the multiparametric assessment of the structural and metabolic modifications we established in our laboratory the Broadband Coherent Anti-Stokes Raman scattering (BCARS) microscopy. The method detects with high specificity the chemical fingerprints of cells, tissues or biofluids. BCARS is based on the detection of the fingerprint region of molecules (500-1500 cm^-1) and could probe multiple Raman transitions simultaneously, to allow a “chemical” imaging of biological tissues with improved molecular contrast.

Atomic Force Microscopy (AFM) in imaging and force spectroscopy mode is used to acquire high resolution (nano-micro-scaled) images of live cells or tissues and to measure their nanobiomechanical response in terms of elastic (Young) modulus. Our studies indicate the concomitance of important structural and mechanical modifications in the diseased state of a tissue or a cell.

Research Fields :

• Elaborating peptide-route functionalized photonic sensors for high sensitivity molecular detection ; application of porous silicon (PSi) microcavities for label-free serodiagnosis of cancer (Univ. Sans Luis Potosi, Univ Cuernavaca -Mexico)
• Strategies for selective functionalization of amorphous chalcogenide rib waveguides (Inst. Charles Gerhardt Montpellier)
• Nonlinear optical microscopy of dental tissues for label-free carries detection ; Raman studies on dental stem cells differentiation and monitoring drug delivery and uptake; 3-D Rheological properties and collagen fibers orientation in murine periodontal ligaments (Laboratoire Bioingénierie et Nanosciences UR UM104, Université Montpellier)
• Biophysics of sensory and motor neuron regeneration ; nanobiomechanics of mytotubes and role of T-lymphocytes in motoneurons death in ALS diseased mice model (Institut de Neurosciences Montpellier UMR1298 INSERM – Université de Montpellier)
• Dynamics of assembly of casein micelles, morphology and nanomechanics of casein micelle nanogels. (IATE – Univ. Montpellier, UMR 1208 INRA, CIRAD SUPAGRO)
• Organization of collagen fibers and tissue hardening : markers of fibrotic scarring after spinal cord injury in mice revealed by multiphoton-atomic force microscopy imaging. (MMDN, U1198, Université de Montpellier, INSERM, École Pratique des Hautes Études)
• Internal structure and remodeling in dystrophin-deficient cardiomyocytes using second harmonic generation (PhyMedExp Inserm U1046-CNRS UMR9214-University of Montpellier)
• Hyper Rayleigh Scattering from DNA Nucleotides in Aqueous Solution (Institut Lumière Matière , Lyon)

Instrumentation :

The Bioimaging facility of the Biophotonics team includes the following techniques:

• Optical waveguide lightmode spectroscopy (OWLS)
• Inverted optical microscope (Nikon-TE2000) also working in epi-fluorescence and differential interference (Nomarski) contrast mode
• Atomic Force microscopy (MFP3D-Asylum Research) mounted on an inverted optical microscope (Olympus) also working in epi-fluorescence and phase contrast
• Multiphoton microscope mounted on an upright scanning microscope (SliceScope, Scientifica Ltd) equipped with a galvanometer scan head, working in two-photon excited fluorescence and second harmonic generation
• Second Harmonic Scattering (SHS) spectroscopy
• Broadband Coherent Raman Spectroscopy (BCARS) imaging

Recent theses :

• MANESCO Clara (2019-2023)
• ROBERT Bruno (2018-2021)