Cyclic Peptide–Selenium Nanoparticles as Drug Transporters

[Image: see text] A cyclic peptide composed of five tryptophan, four arginine, and one cysteine [W(5)R(4)C] was synthesized. The peptide was evaluated for generating cyclic peptide-capped selenium nanoparticles (CP–SeNPs) in situ. A physical mixing of the cyclic peptide with SeO(3)(–2) solution in water generated [W(5)R(4)C]–SeNPs via the combination of reducing and capping properties of amino acids in the peptide structure. Transmission electron microscopy (TEM) images showed that [W(5)R(4)C]–SeNPs were in the size range of 110–150 nm. Flow cytometry data revealed that a fluorescence-labeled phosphopeptide (F′-PEpYLGLD, where F′ = fluorescein) and an anticancer drug (F′-dasatinib) exhibited approximately 25- and 9-times higher cellular uptake in the presence of [W(5)R(4)C]–SeNPs than those of F′-PEpYLGLD and dasatinib alone in human leukemia (CCRF-CEM) cells after 2 h of incubation, respectively. Confocal microscopy also exhibited higher cellular delivery of F′-PEpYLGLD and F′-dasatinib in the presence of [W(5)R(4)C]–SeNPs compared to the parent fluorescence-labeled drug alone in human ovarian adenocarcinoma (SK-OV-3) cells after 2 h of incubation at 37 °C. The antiproliferative activities of several anticancer drugs doxorubicin, gemcitabine, clofarabine, etoposide, camptothecin, irinotecan, epirubicin, fludarabine, dasatinib, and paclitaxel were improved in the presence of [W(5)R(4)C]–SeNPs (50 μM) by 38%, 49%, 36%, 36%, 31%, 30%, 30%, 28%, 24%, and 17%, respectively, after 48 h incubation in SK-OV-3 cells. The results indicate that CP–SeNPs can be potentially used as nanosized delivery tools for negatively charged biomolecules and anticancer drugs.