New insights into the interaction between femtosecond laser and living tissue

The N-linear optical microscope has completely changed our ability to observe and understand complex biological processes. However, light can also harm organisms. However, little is known about the mechanisms behind the irreversible disturbances of strong light on cellular processes.

To address this gap, the research teams of Hanieh Fattahi and Daniel Wehner from the Max Planck Institute for Photoscience (MPL), as well as Max Planck Zentrum f ü r Physik und Medizin, collaborated to determine the conditions under which strong pulsed lasers can be used in the body without damaging the organism.

The international team based in Erlangen used vertebrate zebrafish to investigate the mechanism of deep tissue light damage triggered by femtosecond excitation pulses at the cellular level. The research results have been published in the Journal of Communication Physics.

The first author of this publication, Dr. Soyeon Jun from the MPL "Femtosecond Field Mirror" group led by Fattahi, explained, "We have demonstrated that when the central nervous system (CNS) of zebrafish is irradiated with 1030 nm femtosecond pulses, it suddenly occurs at the extreme peak intensity required for low-density plasma formation.".

As long as the peak intensity is below the low plasma density threshold, this allows for non-invasive increase in imaging residence time and photon flux during 1030 nm irradiation. This is crucial for nonlinear unlabeled microscopes.

"These findings have greatly promoted the advancement of deep tissue imaging technology and innovative microscopy techniques, such as femtosecond field microscopy, which is currently being developed in my group. This technology can capture high spatial resolution, unlabeled images with attosecond time resolution," Fattahi said.

"Our research findings not only highlight the value of collaboration in the fields of physics and biology, but also pave the way for in vivo applications to achieve precise manipulation of the central nervous system based on light," added Wehner, head of the Neuroregeneration Research Group.

Source: Laser Net