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. Author manuscript; available in PMC: 2014 Jan 1.
Published in final edited form as: Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2012 Sep 13;5(1):31–48. doi: 10.1002/wnan.1197

Figure 1.

Figure 1

MMP-2 cleavage of PEG controlled cellular uptake of quantum dots. Streptavidin-coated quantum dots (QD-strep) (red – top row) achieved little internalization by GFP-expressing MDA-MB-435 melanoma cells (green – bottom row, merged with top row). Functionalization of the quantum dot surface with biotin-CPP increased cellular uptake, while addition of removable PEG (biotin-substrate-PEG) decreased the internalization by blocking interactions of the CPP with the cell surface. Cellular uptake was recovered in the presence of MMP-2 with cleavage of the substrate-PEG linker, as the CPPs could interact with the cell surface following the removal of PEG. Reprinted with permission from Ref 63 Copyright 2009 American Chemical Society.