Nanoparticle Multivalency Directed Shifting of Cellular Uptake Mechanism

Although nanoparticle multivalency is known to influence their biological labeling performance, the functional role of multivalency is largely unexplored. Here we show that the folate receptor mediated cellular internalization mechanism of 35–50 nm nanoparticle shifts from caveolae- to clathrin-mediated endocytosis as the nanoparticle multivalency increases from 10 to 40 and results in the difference of their subcellular trafficking. We have synthesized folate functionalized multivalent quantum dot (QD) with varied average numbers of folate per QD between 10 and 110 [e.g., QD­(folate)₁₀, QD­(folate)₂₀, QD­(folate)₄₀, QD­(folate)₁₁₀] and investigated their uptake and localization into folate receptor overexpressed HeLa and KB cells. We found that uptake of QD­(folate)₁₀ occurs predominantly via caveolae-mediated endocytosis and entirely trafficked to the perinuclear region. In contrast, uptake of QD­(folate)₂₀ occurs via both caveolae- and chathrin-mediated endocytosis; uptake of QD­(folate)₄₀ and QD­(folate)₁₁₀ occurs predominantly via clathrin-mediated endocytosis and these three QDs localize predominantly at lysosome with restricted trafficking to the perinuclear region. This work shows the functional role of multivalent interaction in cellular endocytosis and intracellular trafficking which can be exploited for subcellular targeting applications.