Nonlinear dynamics of femtosecond laser interaction with the central nervous system in zebrafish

TL;DR

This study explores how femtosecond laser pulses cause tissue damage in zebrafish's central nervous system, revealing two cavitation regimes and the effects of laser parameters on damage mechanisms, aiding precise optical injury techniques.

Contribution

It identifies distinct cavitation regimes and the influence of laser parameters on tissue damage, advancing understanding of nonlinear laser-tissue interactions in biological systems.

Findings

Low repetition rate damage is confined by plasma ablation.

High repetition rate causes collateral damage via photochemistry.

Cell death and immune responses are observed post-irradiation.

Abstract

Understanding the photodamage mechanism underlying the highly nonlinear dynamic of femtosecond laser pulses at the second transparent window of tissue is crucial for label-free microscopy. Here, we report the identification of two cavitation regimes from 1030 nm pulses when interacting with the central nervous system in zebrafish. We show that at low repetition rates, the damage is confined due to plasma-based ablation and sudden local temperature rise. At high repetition rates, the damage becomes collateral due to plasma-mediated photochemistry. Furthermore, we investigate the role of fluorescence labels with linear and nonlinear absorption pathways in optical breakdown. To verify our findings, we examined cell death and cellular responses to tissue damage, including the recruitment of fibroblasts and immune cells after irradiation. These findings contribute to advancing the emerging nonlinear optical microscopy techniques and provide a strategy for inducing precise, and localized injuries using near-infrared femtosecond laser pulses.