SP90-conjugated liposomes enhanced drug delivery and cytotoxicity towards cancer cells, through increased endocytosis.

<p><b>a,</b> Electron micrographs revealing liposomes in the endosomes of BT483 cells treated with SP90-LD (arrows) or CP-LD. Scale bar: 100 nm. <b>b,</b> The percentage of breast cancer cells harboring endocytosed liposomes following treatment with SP90-LD or CP-LD (<i>n</i> = 50 in each group; *<i>P</i><0.01). <b>c,</b> The average number of liposomes in each endosome following treatment with SP90-LD or CP-LD (n = 20 in each group; **<i>P</i><0.01). <b>d,</b> Cells were incubated with either SP90-LD or LD at 37°C. Doxorubicin uptake by the cells was quantified at the indicated times, following the removal of surface-bound liposomal drugs. <b>e,</b> Cells were treated with SP90-LD and LD at varying concentrations. Cell viability was determined by MTT assay, and calculated as a percentage of living cells. Each point represents the mean of four experiments. Error bar, s.d.