Abstract

A novel cell force transducing assay based on liquid crystals has been developed. Human keratinocytes (HaCaTs) attached to and formed localized deformation on the surface of highly flexible cholesteryl ester liquid crystals. Cells have shown affinity to the lyotropic phase of the cholesteric liquid crystals which was immersed in culture media. In studying the nature of the attachment, 30μM cytochalasin-B and 0.25 Trypsin-EDTA were applied in independent experiments to qualitatively evaluate the force transmitted from the cytoskeletons and adhesion proteins to the liquid crystals substrate. 2 formaldehyde was used to fix the cells and to interrogate the mechanical creep effects in the liquid crystals. Cytochalasin-B reduced the forces exerted by the cells on the liquid crystals indicating that the liquid crystal surface could be used to sense forces generated internally by actin filaments. This study was supported by an additional experiment in which cells attachment was inhibited by the trypsin indicating the forces induced on the liquid crystals by the actin filaments were transmitted to the surface via protein couplings, i.e., focal contacts. Cells morphologies were also distinctly different in both treatments. The study on the creep effects at micro scale showed that a constant stress on the material imposed a regular strain on the material. Liquid crystals has shown stability in response to a constant and long term stress over a period of three days. The experiments demonstrated that the cholesteric liquid crystals could provide a flexible substrate to which cells readily attached, whilst enabling stable transduction of forces generated internally and transmitted to the liquid crystals film via cell surface receptors over a period of several days.