Figure 2.

Evaluation of cellular viability in HeLa, UD-SCC-2, and VX2 cells. Cellular viability was assessed with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay to determine the dark toxicity and phototoxicity of curcumin-loaded liposomes (A, B, and C left) and free curcumin using dimethyl sulfoxide (DMSO) as a vehicle (A, B, and C right). Dark toxicity and phototoxicity were determined by incubation of curcumin liposomes and free curcumin (in DMSO) for 4 h in the concentration range of 0–100 µmol/L at light fluences of 1, 3, and 5 J·cm⁻². Dark refers to untreated cells (0 µmol/L curcumin) and cells treated with free curcumin (in DMSO) or curcumin liposomes without photodynamic therapy (PDT). The half maximal inhibitory concentration (IC₅₀) values were calculated by nonlinear curve fitting for each light fluence. All samples were measured in triplicate, and the data are expressed as mean ± standard deviation. Statistical significances are indicated as *** p < 0.001, ** p < 0.01. § denotes that the viability of cells treated with free curcumin (in DMSO) is significantly (p < 0.001) lower than in the corresponding curcumin (liposomes)-treated cells.