Lithium ion induced stabilization of the liquid crystalline DNA |
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Authors: | Sundaresan Neethu Thomas Thresia Thomas Thekkumkat John Pillai Chennakkattu Krishna Sadasivan Pillai Chennakkatu Krishna Saolashiuan |
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Institution: | Chemical Sciences & Technology Division, Regional Research Laboratory, Council of Scientific and Industrial Research, Thiruvananthapuram 695019, India. |
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Abstract: | A comparative study of the effects of alkali metal ions Li(+), Na(+), K(+), Rb(+), and Cs(+) on the liquid crystalline organization of high-molecular-weight calf thymus DNA using polarized light microscopy was performed. Major differences in the behavior of Li(+) as compared to the other ions were found. Critical DNA concentration expected to exhibit anisotropic behavior was found to be the same for all the monovalent ions, except for Li(+). DNA initially showed cholesteric textures, which later changed to higher ordered columnar phase for all ions, with the cholesteric-columnar transition facilitated upon increasing the size of the counterion. For Li(+) ion, a nematic schlieren-like texture was formed initially, which after a few days changed to a highly stable (for more than 2 months) biphasic cholesteric-columnar arrangement. The observed differences between Li(+) and other alkali metal ions could be rationalized on the basis of the higher number of hydration water molecules of Li(+) and its complexation behavior. Highly stable DNA mesophases may find applications in the field of nanoelectronics, in designing biosensing units, and in DNA chips. |
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Keywords: | cholesteric columnar hexagonal liquid crystalline DNA lithium ion polarized light microscopy schlieren |
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