Peptide-induced dye leakage assay

Aliquots of the calcein-entrapped liposomes were diluted to a final lipid concentration of 90 μM lipid prior to use. The peptides were added to and incubated with the aliquots for 15 min at final concentrations of 0.5, 2, 5, and 20 μM. The leakage of calcein was detected by measuring the fluorescence intensity at an excitation wavelength of 485 nm and 530 nm (emission). 100% dye release was obtained from the liposomes with the addition of 10% (v/v) Triton X-100 in Tris buffer (20 μL, pH 7.4). The percentage of calcein release was calculated using the equation⁵⁰: dye release (%) = (F_obs − F₀)/(F₁₀₀ − F₀) × 100%, where F_obs is the fluorescence intensity of a peptide liposome/calcein solution, F₀ is the fluorescence intensity of liposomes, and F₁₀₀ is the fluorescence intensity of the solvent with the addition of Triton X-100.