Cellular Internalization of Quantum Dots Noncovalently Conjugated with Arginine-Rich Cell-Penetrating Peptides


Protein transduction domains comprised of basic amino acid-rich peptides, can efficiently deliver covalently fused macromolecules into cells. Quantum dots (QDs) are luminescent semiconductor nanocrystals that are finding increasing application in biological imaging. Previous studies showed that protein transduction domains mediate the internalization of covalently attached QDs. In this study, we demonstrate that arginine-rich intracellular delivery peptides (cell-penetrating peptides; CPPs), analogs of naturally-occuring protein transduction domains, deliver noncovalently associated QDs into living cells; CPPs dramatically increase the rate and efficiency of cellular uptake of QD probes. The optimal molecular ratio between arginine-rich CPPs and QD cargoes for cellular internalization is approximately 60:1. Upon entry into cells, the QDs are concentrated in the perinuclear region. There is no cytotoxicity following transport of QDs present at concentrations up to 200 nM. The mechanism for arginine-rich CPP/QD complexes to traverse cell membrane appears to involve a combination of internalization pathways. These results provide insight into the mechanism of arginine-rich CPP delivery of noncovalently attached cargoes, and may provide a powerful tool for imaging in vivo.


Biological Sciences

Keywords and Phrases

Cell-Penetrating Peptides (CPP); Cellular Internalization; Polyarginine; Protein Transduction Domain (PTD); Quantum Dots (QD); Amino Acids; Arginine; Bacteriophages; Cell Membranes; Cytology; Peptides; Semiconductor Quantum Dots; Peptide; Analysis of Variance; Cell Survival; Chemistry; Drug Effect; Endocytosis; Gel Mobility Shift Assay; Protein Transport; Spectrofluorometry; Tumor Cell Line; Cell Line, Tumor; Electrophoretic Mobility Shift Assay; Humans; Particle Size; Peptides; Spectrometry, Fluorescence

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Article - Journal

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© 2010 American Scientific Publishers, All rights reserved.

Publication Date

01 Jan 2010

PubMed ID