Final answer:
Cell-penetrating peptides (CPPs) are vehicles that deliver drugs or DNA within the body and can be associated with liposomes for targeted drug delivery, especially in tumor cells.
Step-by-step explanation:
Cell-penetrating peptides (CPPs) are vehicles to deliver drugs or DNA within the body; they can be linked to the liposome wall or contained at high concentration within its lumen. CPPs, which were discovered over 20 years ago, are now becoming increasingly associated with the biodistribution and efficacy of oral bio-drug delivery. The recent progress of CPPs as new carriers for intracellular cargo delivery is particularly focused on tumor cells, where a small quantity of drugs used as cargo can have significant therapeutic effects.
Furthermore, liposome-based delivery systems have been widely used in cancer therapeutics due to their biocompatibility, the ability to carry both hydrophilic and hydrophobic drugs, and their potential for targeted delivery.