Nona-Arginine Facilitates Delivery of Quantum Dots into Cells via Multiple Pathways

Abstract

Semiconductor quantum dots (QDs) have recently been used to deliver and monitor biomolecules, such as drugs and proteins. However, QDs alone have a low efficiency of transport across the plasma membrane. In order to increase the efficiency, we used synthetic nona-arginine (SR9), a cell-penetrating peptide, to facilitate uptake. We found that SR9 increased the cellular uptake of QDs in a noncovalent binding manner between QDs and SR9. Further, we investigated mechanisms of QD/SR9 cellular internalization. Low temperature and metabolic inhibitors markedly inhibited the uptake of QD/SR9, indicating that internalization is an energy-dependent process. Results from both the pathway inhibitors and the RNA interference (RNAi) technique suggest that cellular uptake of QD/SR9 is predominantly a lipid raft-dependent process mediated by macropinocytosis. However, involvement of clathrin and caveolin-1 proteins in transducing QD/SR9 across the membrane cannot be completely ruled out.

Arginine-rich cell-penetrating peptides deliver gene into living human cells

“…The safety of most CPPs has been confirmed in a detailed metabolic analysis (Kilk et al, 2009). Our previous results demonstrated that CPPs do not cause cytotoxicity in cells as indicated by trypan blue (Chang et al, 2005aDai et al, 2011a;Hou et al, 2007;Wang et al, 2006Wang et al, , 2007, 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) (Chen et al, 2012;Hou et al, 2007;Wang et al, 2007), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) (Xu et al, 2010), and sulforhodamine B (SRB) (Hu et al, 2009;Lee et al, 2011;Liu et al, 2010aLiu et al, , 2011 assays. Recently, detailed studies reported that CPPs are nontoxic and nonimmunogenic in vitro and in vivo (Suhorustsenko et al, 2011).…”

“…The recent identification of nontoxic cell-penetrating peptides (CPPs) has led to the development of a new nonviral technology for delivering biological macromolecules (Deshayes et al, 2010;Gump and Dowdy, 2007) and nanomaterials (Liu et al, 2010a(Liu et al, , 2010b(Liu et al, , 2011Xu et al, 2010) into live cells. CPPs, also known as protein transduction domains, are a group of short cationic peptides originally derived from a viral protein (Frankel and Pabo, 1988;Green and Loewenstein, 1988;Gump and Dowdy, 2007).…”

Intracellular delivery of quantum dots mediated by a histidine- and arginine-rich HR9 cell-penetrating peptide through the direct membrane translocation mechanism

“…Covalently linking QDs and CPPs is a lengthy process that requires purification and chemical identification. Our studies have demonstrated that noncovalent linking is effective, inexpensive and relatively easy [15,24,25].…”

“…However, QDs alone do not readily enter cells, and aggregation often occurs after internalization [19,20]. To overcome these limitations, surface modified QDs functionalized by covalent [21e23] or noncovalent [15,24,25] linkages with CPPs, denoted as CPP-QDs or CPP/QDs respectively, have been introduced recently.…”

“…Most conjugation methods involve either covalent linkage with thiol groups [21e23] or noncovalent linkage via biotinestreptavidin interactions [15,24,25] between QDs and CPPs. Covalently linking QDs and CPPs is a lengthy process that requires purification and chemical identification.…”