In vitro imaging of cells using peptide-conjugated quantum dots

Mitsuru Ishikawa; Vasudevan Biju

doi:10.1117/12.851055

17 February 2010 In vitro imaging of cells using peptide-conjugated quantum dots

Mitsuru Ishikawa, Vasudevan Biju

Proceedings Volume 7575, Colloidal Quantum Dots for Biomedical Applications V; 75750R (2010) https://doi.org/10.1117/12.851055
Event: SPIE BiOS, 2010, San Francisco, California, United States

Abstract

Efficient intracellular delivery of quantum dots (QDs) in living cells and elucidating the mechanism of the delivery are essential for advancing the applications of QDs to in vivo imaging and in vivo photodynamic therapy. Here, we demonstrate that clathrin-mediated endocytosis is the most dominant pathway for the delivery of peptide-conjugated QDs. We selected an insect neuropeptide, allatostatin (AST1), conjugated with CdSe-ZnS QDs, and investigated the delivery of the conjugate in living cells. We evaluated the contributions of clathrin-mediated endocytosis, receptormediated endocytosis, and charge-based cell penetration to the delivery of QD605-AST1 conjugates by flow cytometry and fluorescence video microscopy. The delivery was suppressed by ~57% in inhibiting phosphoinositide 3-kinase with wortmannin, which blocks the formation of clathrin-coated vesicles, and by ~45% in incubating the cells at 4°C. Also, we identified clathrin-mediated endocytosis by two-color experiment to find colocalization of QD560-labeled clathrin heavy-chain antibody and QD605-AST1. We further observed reduction of the galanin receptor-mediated delivery of QD605-AST1 by ~8% in blocking the cells with a galanin antagonist, and reduction of charge-based cell penetration delivery by ~30% in removing the positive charge in the peptide from arginine and suppressing the cell-surface negative charge from glycosaminoglycan.

Citation Download Citation

Mitsuru Ishikawa and Vasudevan Biju "In vitro imaging of cells using peptide-conjugated quantum dots", Proc. SPIE 7575, Colloidal Quantum Dots for Biomedical Applications V, 75750R (17 February 2010); https://doi.org/10.1117/12.851055

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