Investigations on the liquid crystalline phases of cation-induced condensed DNA |
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Authors: | C K S Pillai Neethu Sundaresan M Radhakrishnan Pillai T Thomas T J Thomas |
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Institution: | (1) Regional Research Laboratory, 695 019 Thiruvananthapuram, India;(2) Rajeev Gandhi Centre for Biotechnology, 695 014 Thiruvananthapuram, India;(3) Departments of Medicine and Environmental and Community Medicine, University of Medicine and Dentistry, Robert Wood Johnson Medical School, 08903, NJ, USA |
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Abstract: | Viral and nonviral condensing agents are used in gene therapy to compact oligonucleotides and plasmid DNA into nanostructures
for their efficient transport through the cell membranes. Whereas viral vectors are best by the toxic effects on the immune
system, most of the nonviral delivery vehicles are not effective for use in clinical system. Recent investigations indicate
that the supramolecular organization of DNA in the condensed state is liquid crystalline. The present level of understanding
of the liquid crystalline phase of DNA is inadequate and a thorough investigation is required to understand the nature, stability,
texture and the influence of various environmental conditions on the structure of the phase. The present study is mainly concerned
with the physicochemical investigations on the liquid crystalline transitions during compaction of DNA by cationic species
such as polyamines and metallic cations. As a preliminary to the above investigation, studies were conducted on the evolution
of mesophase transitions of DNA with various cationic counterion species using polarized light microscopy. These studies indicated
significant variations in the phase behaviour of DNA in the presence of Li and other ions. Apart from the neutralization of
the charges on the DNA molecule, these ions are found to influence selectively the hydration sphere of DNA that in turn influences
the induction and stabilization of the LC phases. The higher stability observed with the liquid crystalline phases of Li-DNA
system could be useful in the production of nanostructured DNA. In the case of the polyamine, a structural specificity effect
depending on the nature, charge and structure of the polyamine used has been found to be favoured in the crystallization of
DNA. |
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Keywords: | Liquid crystalline DNA alkali metal ions DNA condensation nanostructured DNA |
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