The emerging field of nanomedicine brings nanotechnology and medicine together to develop new therapies. In the last decades there has been a remarkable progress in the development of nanocarriers for targeted delivery of drugs to tumors. In addition to passive targeting, defined as the accumulation of the nanocarriers in the tumor tissue due to the abnormal tumor microenvironment, the surface of drug delivery systems can be modified with a ligand that specifically recognizes cancer cells. One of the most popular ligands is the hyaluronic acid (HA), a major component of the extracellular matrix. It accumulates at sites of cell division and rapid matrix remodeling, and is therefore linked to cancer progression. The major cell-surface receptor for HA is the CD44, a receptor that is highly expressed in many cancer cells. Our preliminary results have shown that CD44-mediated endocytosis of HA-coated nanocarriers is affected by the mechanical properties of the extracellular matrix surrounding the cells. However, how the micro-environment influences this process is not yet known. In this project we aim to dissect the role of matrix mechanics on CD44-HA interactions. We will combine novel 3D biomimetic hydrogels, with tunable mechanical properties, functionalized nanoparticles and advanced 3D (super-resolution) fluorescence microscopy to unravel the role of mechanics in CD44 mediated endocytosis of nanoparticles functionalized with HA. To evaluate the link between the effects of the microenvironment and cancer metastasis, we will use two isogenic colorectal cancer cell lines, with different metastatic potential, and compare the obtained results. A better understanding of the molecular mechanisms behind the cellular uptake of nanoparticles will yield improved targeting strategies and subsequently more efficient anti-cancer therapeutics.