  Mesoscale molecular assemblies on the cell surface, such as cilia and
filopodia, integrate information, control transport and amplify signals.
Synthetic devices mimicking these structures could sensitively monitor these
cellular functions and direct new ones. The challenges in creating such
devices, however are that they must be integrated with cells in a precise
kinetically controlled process and a device's structure and its precisely
structured cell interface must then be maintained during active cellular
function. Here we report the ability to integrate synthetic micro-scale
filaments, DNA nanotubes, into a cell's architecture by anchoring them by their
ends to specific receptors on the surfaces of mammalian cells. These filaments
can act as shear stress meters: how anchored nanotubes bend at the cell surface
quantitatively indicates the magnitude of shear stresses between 0-2 dyn per
cm2, a regime important for cell signaling. Nanotubes can also grow while
anchored to cells, thus acting as dynamic components of cells. This approach to
cell surface engineering, in which synthetic biomolecular assemblies are
organized within existing cellular architecture, could make it possible to
build new types of sensors, machines and scaffolds that can interface with,
control and measure properties of cells.
