Chemistry Department, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
J Colloid Interface Sci. 2012 Oct 1;383(1):63-74. doi: 10.1016/j.jcis.2012.06.011. Epub 2012 Jun 15.
Associative aqueous mixtures over a range of concentrations of double- (ds) or single- (ss) stranded DNA with dilute or semidilute solutions of two cationic derivatives of hydroxyethyl cellulose (cat-HEC and cat-HMHEC,(1) the latter carrying grafted hydrophobic groups), were studied. The phase behavior showed an interesting asymmetry: Phase separation occurred immediately when small (sub-stoichiometric) amounts of cationic polyelectrolyte were added to the DNA solution, but redissolution into a single cat-(HM)HEC/DNA/H(2)O phase occurred already with a modest charge excess of the cationic polyelectrolyte, at a charge ratio approximately independent of the overall polyelectrolyte concentration. Cat-HEC/dsDNA/H(2)O and cat-HEC/ssDNA/H(2)O systems presented a considerable difference in the extension of the phase separation region. The one-phase samples with excess cationic polyelectrolyte were studied by rheology. The presence of DNA strengthened the viscoelastic behavior of the solutions of the cationic polyelectrolytes, reflected in an increase in storage modulus and viscosity. Differences in phase behavior and rheology were observed, particularly between systems containing cat-HEC or cat-HMHEC, but also between dsDNA and ssDNA. Thus, these systems allow for the preparation of DNA formulations with widely variable rheology and water uptake.
研究了双（ds）或单（ss）链 DNA 与两种阳离子羟乙基纤维素衍生物（cat-HEC 和 cat-HMHEC，（1）后者带有接枝的疏水性基团）稀溶液或半稀溶液在浓度范围内的缔合水混合物。相行为表现出有趣的不对称性：当向 DNA 溶液中加入少量（亚化学计量的）阳离子聚电解质时，立即发生相分离，但当阳离子聚电解质的电荷过量适度时，已经重新溶解到单一的 cat-（HM）HEC/DNA/H2O 相中，在大约与聚电解质总浓度无关的电荷比下。cat-HEC/dsDNA/H2O 和 cat-HEC/ssDNA/H2O 系统在相分离区域的扩展方面存在显著差异。用流变学研究了含有过量阳离子聚电解质的单相样品。DNA 的存在增强了阳离子聚电解质溶液的粘弹性行为，表现为储能模量和粘度的增加。观察到相行为和流变学的差异，特别是在含有 cat-HEC 或 cat-HMHEC 的系统之间，以及 dsDNA 和 ssDNA 之间。因此，这些系统允许制备具有广泛可变流变学和吸水率的 DNA 制剂。
