4.4. Viability Assay

The cells were cultured in a white-wall 96-well Costar plates (Corning, Somerville, MA, USA) as required cell density in order to triplicate each condition (Non-Treated, Light Only, 5-ALA Only, PDT Treated). 100 µL of Celltiter-Glo mix (Promega, Madison, WI, USA), which determines the cellular viability in a culture based on the quantification of the ATP present, was prepared according to the manufacturer’s instructions, was added to each well and incubated at room temperature for 10 min in the dark. Luminescence reading was performed using the Luminometer centro LB960 (Berthold Technologies, Oak Ridge, TN, USA) running MikroWin software Version 4.41 (Mikrotek Laborsysteme GmbH, Overath, Germany). Results were expressed in relative luminescence units (RLU) or normalized RLU. Normalized RLU = RLU of the sample/Average RLU of Non-Treated control.