DNA Liquid-Crystalline Dispersions and Nanoconstructions

A Dual Effect of Au-Nanoparticles on Nucleic Acid Cholesteric Liquid-Crystalline Particles

“…According to the theory [11,13], the appearance of these abnormal (negative or positive) bands unequivocally testify the macroscopic, cholesteric, twist of neighboring NA molecules in particles of dispersion formed as a result of their phase exclusion from PEG-containing watersalt solutions. The negative sign of the band in the CD spectrum proves the left-handed cholesteric twist of the right-handed DNA molecules (B-form, curve 1), whereas the positive sign corresponds the right-handed cholesteric twist of the right-handed poly(I)xpoly(C) molecules (A-form, curve 1 I ) in the formed particles.…”

“…The method of preparation of control cholesteric liquidcrystalline dispersions (CLCDs) of nucleic acids (NA) (control 1) in PEG-containing water-salt solutions is described in [11]. This method was used for preparation of dispersions and phases of ds NA CLCD treated with Aunanoparticles (see "Experiments" above).…”

“…This means that great importance is attached to creation of simple model systems to test the effects of nanomaterials under reasonable conditions. Despite the fact that in vivo conditions are different from in vitro, one of these model system is the so-called "cholesteric liquid crystals" and "cholesteric liquid-crystalline dispersions" of ds DNA molecules [11]. Indeed, the physico-chemical properties of ds DNA cholesteric liquid-crystalline dispersions (CLCDs) reflect some properties of these macromolecules in biological objects such as chromosomes of primitive organisms (for instance, chromosomes of the Dinoflagellate, etc.)…”

“…Hence, this test-system is not only of nanotechnological, but of biotechnological interest. Here one can add, that due to the high local concentration of the ds DNA molecules and their ordered arrangement in particles of CLCD, the low-molecular-mass chemical and biologically active compounds quickly diffuse into the content of particles of CLCD and interact with ds DNA molecules forming different complexes [11]. This process induces an appearance peculiarities (specific for these compounds) in the circular (CD) spectra [13].…”

Spatial ordering and abnormal optical activity of DNA liquid-crystalline dispersion particles

“…It is well known that the phase exclusion of the low molecular mass, rigid, linear, ds DNA (molecular mass <1u10 6 Da) is realized under intensive mixing (stirring) of equal volumes the water-salt solutions containing poly(ethyleneglycol), PEG, with water-salt solutions containing a very low (5-10 μg ml -1 ) concentration of ds DNA at room temperature. As a result the formation of the liquid-crystalline dispersions (LCDs) of these molecules takes place [1]. The particles of the low molecular mass ds DNA dispersions are microscopic droplets of concentrated DNA solution, which cannot be taken in hand (The mode of the ds DNA packing in the LCD particles can model the packing of ds DNA in the primitive biological objects above).…”