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A new method for transferring fullerene from a solution in chloroform to an aqueous medium with the use of water-soluble polymers poly-N-vinylpyrrolidone (PVP), polyethylene oxide (PEO) and DNA is suggested. A saturated solution of fullerene in chloroform (II) was added to aqueous solutions of polymers (water-salt solutions of DNA) in an amount equal to the limiting solubility of chloroform in water (I) (0.822 g/dl, which corresponded to the concentration of fullerene cful= 1.315 × 10-2 g/dl = 1.77 × 10-6 M). For comparison, aqueous solutions of polymers containing chloroform only (test systems) were studied. A mixture of fullerenes C 60 and C70 (C60/70) and pure C60 were used. The solubility of I and II in water was found to increase in the presence of polymers (PVP, PEO, or DNA), that is, chloroform and fullerene were solubilized by macromolecules. In fact, this was evidence of fullerene interactions with polymers with the formation of fullerene-chloroform-polymer complexes. Solutions (PEO + II) and (PVP + II) and the corresponding test systems were studied; the solutions contained I and II in amounts 2-4 times higher than the limiting solubility of I in water. The addition of I to solutions of PVP and PEO did not influence the size of macromolecules, whereas the presence of II decreased the specific volume of molecular coils by ∼ 10-20% and considerably changed the optical density Dλ of the systems compared with the sum of the Dλ values of the components. The presence of chloroform alone in solutions of DNA decreased their characteristic viscosity [η], and the addition of fullerene caused a still more substantial viscosity drop. The degree of a decrease in [η] depended on experimental conditions and was 15-40%. The DNA molecule retained its double helical B shape and equilibrium rigidity (persistent length) when either I or II was added to its solution.
Original language | English |
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Pages (from-to) | 526-532 |
Number of pages | 7 |
Journal | Russian Journal of Physical Chemistry A |
Volume | 78 |
Issue number | 4 |
State | Published - Apr 2004 |
ID: 72775779