Liquid crystal effects on bacterial viability

Abstract

The primary objective of this research was to test the hypothesis that lyotropic chromonic liquid crystals (neutral grey, red 14, blue 27, cromolyn) are not toxic to bacteria as compared with surfactant‐based lyotropic (CPCl and CsPFO) or thermotropic (5CB and E7) liquid crystals. Biocompatibility of most liquid crystals is currently unknown and is required for the development of systems interfacing liquid crystals and biological systems. Potential liquid crystal toxicity was evaluated by two methods. The first examined bacterial survival measured by bacterial growth over 24 hours, after exposure to various liquid crystals. The second toxicity method evaluated liquid crystal effects on bacterial membrane permeability using two fluorescent dyes. Three different types of bacteria were evaluated to assess bacterial structure differences with respect to liquid crystal toxicity. The results of this study indicate that lyotropic chromonic liquid crystals are not toxic to bacteria, whereas thermotropic and surfactant‐based lyotropic liquid crystals are toxic to one or more forms of bacteria. We conclude that lyotropic chromonic liquid crystals may be the preferred material in designing liquid crystal‐based systems that interact with biological systems, especially in the use of liquid crystal‐based biosensors.

Acknowledgements

We acknowledge Shannon Helfinstine for technical assistance. This research was partially supported by the National Science Foundation and the Intelligence Technology Innovation Center through the joint ‘Approaches to Combat Terrorism’ Program Solicitation NSF 03‐569 (DMR‐0346348) and by an Ohio Board of Reagents Research Challenge Grant. We gratefully acknowledge the generous donation by Mrs Glenn H. (Jessie) Brown in support of this research. Summer undergraduate research of E. Gustely was supported by the US Depatment of Education fund for Center for Liquid Crystal Science and Education at the Liquid Crystal Institute.