Cancer cell uptake of polymer hydrogel nanotubes

To gain deeper understanding of how the shape and size of particles influence their interaction with cells, the uptake process of polymer hydrogel nanotubes (PNTs) by cancer cells was characterized. The PNTs were composed of crosslinked poly(ethylene glycol) segments with a diameter of 300 nm and a polydispersed length in the range of 2 to 20 μm. The uptake of PNTs into human cervical carcinoma epithelial (HeLa) cells cultured in vitro was monitored by confocal laser fluorescence microscopy and details of PNT entry into cells were revealed by a series of confocal Z-section images and time-lapsed video microscopy. It was found that PNTs initiating contact with the cell membrane through the tips of the tubes were readily taken up by the cells, whereas the uptake of tubes approaching the cell surface in parallel manner was very difficult. The length of the tubes did not appear to affect cellular uptake. In fact, it was found surprisingly that PNTs as long as > 10 μm were internalized by these non-phagocytic cells. The rate of PNT uptake varied significantly and was probably influenced by the angle of attachment. Better understanding of the interaction between PNTs and cells may provide important insight in the use of PNTs as potential anticancer drug delivery vehicles.