PR9 is a peptide comprised of nona-arginine (R9), and a penetration accelerating peptide sequence (Pas) that facilitates escape from endocytic lysosomes. PR9 is able to greatly enhance the delivery of noncovalently associated quantum dots (QDs) into human A549 cells. Mechanistic studies, intracellular trafficking analysis and a functional gene assay show that endocytosis is the main route for intracellular delivery of the PR9/QD complex. The PR9/QD complex is non toxic and so can be used as a safe vector for biomedical applications.
