Evaluation of the phototoxicity in optical imaging using protein dynamics

Phototoxicity is a universal problem in optical imaging. Effective and quantitative evaluation of phototoxicity allows for the optimization of imaging conditions and the minimization of functional perturbation to live biological samples. We found that microtubule polymerization dynamics is a sensitive and reliable readout that can quantify phototoxicity in various imaging conditions. We quantified the photosensitizing effect of common organelle stains under the illumination of different laser wavelengths and compared the phototoxicity of different conditions. By controlling oxygen levels during light treatment, we found that the type I photosensitizing effect is involved in the hypoxia condition. We also evaluated the photoperturbation of IR laser pulses at different average and peak power levels in nonlinear optical imaging. Applying a recently developed real-time precision opto-control system, phototoxicity and reactive oxygen species generated at specific organelles can be studied.