Enhanced cellular internalization of CdTe quantum dots mediated by arginine- and tryptophan-rich cell-penetrating peptides as efficient carriers

Quantum dots (QDs), as a new class of fluorescent tags, have been widely used for biomedical applications. Despite their various advantages, QDs do not efficiently enter cells on their own, and aggregation often occurs following internalization. In the present study, we have designed three QD-cell-penetrating peptide (CPP) complexes to increase the uptake of QD into cells. The results demonstrated that R9 and R5W3R4 form relatively stable noncovalent complexes with QDs, considerably increasing the rate and efficiency of QD uptake by A549 cells. These data suggest that cationic CPPs could efficiently transfer QDs into cells in a non-toxic manner.