A cell nanoinjector based on carbon nanotubes

Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here, we report the development of a nanoscale cell injection system (termed the nanoinjector) that uses carbon nanotubes to deliver cargo into cells. A single multiwalled carbon nanotube attached to an atomic force microscope (AFM) tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this "nanoneedle" was controlled by the AFM. The following reductive cleavage of the disulfide bonds within the cell's interior resulted in the release of cargo inside the cells, after which the nanoneedle was retracted by AFM control. The capability of the nanoinjector was demonstrated by injection of protein-coated quantum dots into live human cells. Single-particle tracking was used to characterize the diffusion dynamics of injected quantum dots in the cytosol. This technique causes no discernible membrane or cell damage, and can deliver a discrete number of molecules to the cell's interior without the requirement of a carrier solvent.