Rheological characterization and in-situ investigation of the time-dependent cholesteric based lyotropic liquid crystals

The impact of cell culture media on the rheology of liquid crystals is critical to developing liquid crystal (LC) based biosensors. The rheological properties of cholesteryl ester based lyotropic liquid crystals (LLC) were investigated in a rotational rheometer and using in-situ methods after incubation in cell culture media for periods of 24, 48 and 72 h. The results of the rheological experiments indicated that for incubation up to 48 h, LLC exhibited a linear viscoelastic behavior < 10% strain at low angular frequencies < 1 s− 1 and an insignificant decrease in the complex viscosity. The in-situ experiments involved examining the response of the LLC to stresses generated by keratinocyte. It was found that cells induced deformations in the liquid crystal surfaces could be completely removed by disrupting the actin cytoskeletons of cells with cytochalasin-B after 48 h in culture media, but could only be partially removed after 48 h in culture media. In fixed stress experiments, it was found that LC deformation lengths remained constant over 72 h and exhibited a statistically insignificant decrease after 72 h in culture media. These later results indicate very little time related change of viscosity in the LLC. However, the in-situ rheological behaviors were in good agreement with the rheological results obtained from oscillatory tests for the LLC incubated up to 48 h. These results suggest that LLC coated substrates have viable physical properties within 48 h of incubation that can allow them to monitor cell-generated stresses in culture.