Protease-modulated cellular uptake of quantum dots.

Quantum dots (QDs) are often cell-impermeable and require transporters to facilitate crossing over cell membranes. Here we present a simple and versatile method that utilizes enzymes, matrix metalloprotease 2 (MMP-2) and MMP-7, to modulate the cellular uptake of QDs. QD-peptide conjugates could be efficiently taken up into cells after the MMP treatment. This enzyme-modulated cellular uptake of QDs may be applied to other nanoparticles for biological imaging and selective drug delivery into tumor cells.