Permission to enter cell by shape: nanodisk vs nanosphere.

Changing polystyrene nanoparticles from three-dimensional spherical shape to two-dimensional disk shape promotes their cell surface binding with significant reduction of cell uptake. As a result of lower cell uptake, nanodisks show very little perturbations on cell functions such as cellular ROS generation, apoptosis and cell cycle progression compared to nanospheres. Therefore, disk-shaped nanoparticles may be a promising template for developing cell membrane-specific and safer imaging agents for a range of biomedical applications such as molecular imaging, tissue engineering, cell tracking, and stem cell separation.