Endocytosis and Intracellular Trafficking Propertiesof Transferrin-Conjugated Block Copolypeptide Vesicles.

Blockpolypeptides are an emerging class of materials that havethe potential to be used in many biomedical applications, includingthe field of drug delivery. We have previously developed a negativelycharged block copolypeptide, poly(l-glutamate)60-b-poly(l-leucine)20(E60L20), which forms spherical vesicles in aqueoussolution. Since these vesicles are negatively charged, they are minimallytoxic toward cells. However, the negative charge also inhibits thesevesicles from effectively being internalized by cells, which can beproblematic as many therapeutics have intracellular targets. To overcomethis limitation of the E60L20vesicles, transferrin(Tf) was conjugated onto the vesicle surface, since the receptor forTf is overexpressed on cancer cells. The enhanced uptake of the Tf-conjugatedvesicle was verified through confocal microscopy. Furthermore, endocytosisand immunostaining experiments confirmed that the Tf conjugated onthe vesicle surface plays a critical role in the internalization andsubsequent intracellular trafficking behavior of the vesicles. [ABSTRACT FROM AUTHOR]