Laser microbeam meets nonlinear and superresolution microscopy

16.06.2025 14:00 – 15:00

Nonlinear absorption with plasma formation enables highly localized energy deposition in nominally
transparent tissues and cells. This opens many avenues for laser cell surgery and for free-electronmediated modifications of biomolecules and tissue properties. Combining a laser microbeam with
confocal, nonlinear, and superresolution fluorescence microscopy enables the create microscopic effects
on cells or biomolecules and to study the subsequent response in vivo. This will be illustrated on two
examples:
1. Probing the immune and healing response of murine intestinal mucosa by time-lapse 2-photon
microscopy of laser-induced lesions,
2. Induction of specific types of DNA damage in living cells that are of interest for studying DNA repair and
the mechanisms of radiotherapy. Nonlinear absorption of femtosecond laser pulses at different
wavelengths can be used to change from photochemical damage through 2-photon absorption at 515 nm
to free-electron-mediated single- and double strand breaks at IR wavelengths(620 nm, 775 nm, 1030 nm).
Effects and cellular repair reactions are monitored by confocal microscopy of immune-histochemical
assays. They are analyzed with the help of numerical simulations of density and kinetic energy spectra of
the laser-generated free-electrons in conjunction with known yield functions for electron-DNA
interactions from radiation physics.
Full-field structured illumination microscopy pushes both image resolution and imaging speed, which may
open new avenues for cellular reaction and repair studies if it can be combined with a laser microbeam.
The last part of the talk explores a potential pathway for such venture.

Lieu

Bâtiment: Ancienne Ecole de médecine

AEM 134

entrée libre