Self-assembly of concentric microrings of tubule and platy nanoclays for cell patterning and capturing

Self-assembly of nanoparticles has become a valuable tool for creation of various nano-textured materials for biomedicine, electronics, optics, photonics and biotechnology. In this paper, polystyrene sulfonate (PSS) modified tubular and platy nanoclays were used for fabrication of concentric ring patterns on solid surfaces based on "coffee-ring" effect. The technique of nanoclay self-assembly into concentric structures described in this paper does not require special equipment and the self-assembly process is rather fast (1-2 h). Two different molds (a metal sphere and a glass pyramid) fixed in close proximity above a cover glass were used for creating confined geometries necessary to control the process of clay suspension evaporation. The resulting concentric patterns were applied for orienting the growth of human skin fibroblasts and capturing cancer and protozoan cells. The concentric structures formed using HNT-PSS suspension and the pyramid were more effective in directing the growth of fibroblasts, while HNT-PSS and KNP-PSS coatings formed by the sphere fitted better for cell capturing.