Influence of femtosecond laser pulse irradiation on the viability of cells at 1035, 517, and 345nm

Abstract

We report on the influence of femtosecond laser pulses at different wavelengths (1035, 517, and 345nm) on chinese hamster ovary cells exposed to intense radiation. The aim of the study was to determine the mean power thresholds from which the cells were influenced by the laser radiation up to irreversible cell damage. An influence of the wavelength has been shown. The damage threshold is lower in the ultraviolet (UV) than in the infrared (IR) by a factor of 5–6. At the green wavelength the threshold value was higher due to the low absorption (i.e., a relatively high transmission). The range between the lowest power where a loss of viability could be observed (25μW) and the mean power for direct cell damage (45μW) is 20μW in the UV. The corresponding range in the IR is between 75 and 240μW and thus about 165μW broad: In the case of UV irradiation, the cells seem to be unaffected close to the ablation or damage threshold at low energy pulses.

Fiber-based tunable repetition rate source for deep tissue two-photon fluorescence microscopy

“…On the other hand, the pulse energy used in this paper (e.g., Fig. 5, ~0.15 nJ at the focus) is significantly below the nonlinear damage threshold for cultured cells [32,33], and approximately 50 to 100 times below the nonlinear ablative damage threshold [34,35]. Pulse energy much higher than the value used in this paper has been used in the past for in vivo 2photon imaging of the mouse brain [3,6].…”

Wide-field medium-repetition-rate multiphoton microscopy reduces photodamage of living cells

“…[13]); a higher number indicates a better imaging throughput. It can be seen that for a medium repetition rate (100 kHz) and a tight focus (500 nm diameter), very high peak intensities (900 -2000 GW/cm 2 ) can be used [24]. This comes, however, at the cost of a very inefficient imaging process.…”

“…The likelihood of producing ROS, avalanche breakdown, or simply thermal damage increases if the system is already in an excited state. Consequently, a significant improvement in the illumination (dwell) [24] Abbreviations: CHO: Chinese hamster ovary [24]; AC: Adrenal chromaffin [9]; HEK: human embryo kidney [25].…”

Optimization of wide-field second-harmonic generation microscopy for fast imaging of large sample areas in biological tissues

“…The opposite is the direction of the dependence on the pulse energy of the illumination fluence. At the same time, with 1.7 μJ of the pulse energy at the sample in our measurement, the fluence is less than 1 mJ/cm 2 , which is well below the known damaging thresholds for different kinds of live cells [17][18][19] and even more so in the case of the tissue samples, where maintaining the cell vivacity is not an issue. In fact, the mouse skin sample did not exhibit any signs of degradation even with ~50× higher fluence in the initial measurement for the maximum image size with only a 4× expanded laser beam and a 40× magnification illumination objective.…”