Chapter 2 │ Page 38 which negatively a ects experimental read-outs and data interpretation. Even before visible indications of photodamage have occurred (e.g. membrane blebbing, mitochondrial enlargement, cell detachment), physiological behavior can be subtly altered in response to the induced cellular stress [9]. A key factor in phototoxicity is the generation of reactive oxygen species (ROS) upon energy transfer from the light-excited fluorophore to nearby oxygen molecules [8]. In particular, recent research has shown that blue light, at intensities used to excite common fluorophores like green fluorescence protein (GFP), negatively influenced cell motility, which was directly linked to the production of the ROS, hydrogen peroxide (H2O2) [12]. Furthermore, quantitative real-time polymerase chain reaction (RT-qPCR) analysis demonstrated an upregulation of several antioxidant genes upon illumination [12]. Other studies concordantly reported the link between phototoxicity and redox disturbance with e ects on the cell cycle, mitochondrial fragmentation, and cell migration in di erent cellular models [8, 10]. Therefore, acknowledging the considerable impact of phototoxicity on cellular physiology is critically needed when fluorescence live-cell imaging analysis is employed for various research applications, particularly when it is used to investigate experimental therapies, such as non-thermal plasma (NTP). Live-cell fluorescence imaging has been a valuable tool in the field of plasma medicine for investigating cellular and subcellular NTP treatment e ects for di erent biomedical applications, including wound healing and cancer therapy [1316]. Mounting evidence has demonstrated that the versatile medicinal properties of NTP arise from the diverse short-lived and persistent reactive species (e.g. •OH, •NO, O/O3, H2O2) that are generated [17-19]. ROS can strongly influence cellular physiology via (i) direct interaction with the plasma membrane and biochemical molecules (e.g. proteins, lipids) and/or (ii) interference with the endogenous antioxidant systems responsible for normal redox balance within the cell [20]. Moreover, the concentration of delivered ROS is determinative for biological
RkJQdWJsaXNoZXIy MTk4NDMw