Cytotoxicity of DOX-loaded and empty PTSL at varying pH. DOX-loaded or empty PTSL in growth media at pH 7.5, 7, and 6.5 were added to cells for 4 hr after which solutions were replaced with pH 7.5 media free of liposomes/drug. Cells were incubated for 192 hr after which cell viabilities were determined via MTT assay. Data shown are averages ± SD for n=6 replicates. a
p=0.01 between pH 7 and pH 6.5, 175 nM DOX-PTSL; b
p=0.001 between pH 7.5 and pH 6.5, 175 nM DOX-PTSL; c
p=0.02 between empty PTSL and DOX-PTSL, 175 nM, pH 6.5; d
p=0.0002 between pH 7.5 and pH 7, 250 nM DOX-PTSL; e
p=0.003 between empty PTSL and DOX-PTSL, 250 nM, pH 7; f
p=0.0002 between pH 7.5 and pH 6.5, 250 nM DOX-PTSL; g
p=0.016 between empty PTSL and DOX-PTSL, 250 nM, pH 6.5. No significant differences were observed as a function of pH in groups administered the same concentration of empty PTSL.