Mechanotargeting: Mechanics-Dependent Cellular Uptake of Nanoparticles.

Targeted delivery of nanoparticle (NP)-based diagnostic and therapeutic agents to malignant cells and tissues has exclusively relied on chemotargeting, wherein NPs are surface-coated with ligands that specifically bind to overexpressed receptors on malignant cells. Here, it is demonstrated that cellular uptake of NPs can also be biased to malignant cells based on the differential mechanical states of cells, enabling mechanotargeting. Owing to mechanotransduction, cell lines (HeLa and HCT-8) cultured on hydrogels of various stiffness are directed into different stress states, measured by cellular force microscopies. In vitro NP delivery reveals that increases in cell stress suppress cellular uptake, counteracting the enhanced uptake that occurs with increases in exposed surface area of spread cells. Upon prolonged culture on stiff hydrogels, cohesive HCT-8 cell colonies undergo metastatic phenotypic change and disperse into individual malignant cells. The metastatic cells are of extremely low stress state and adopt an unspread, 3D morphology, resulting in several-fold higher uptake than the nonmetastatic counterparts. This study opens a new paradigm of harnessing mechanics for the design of future strategies in nanomedicine.