Characterization of pH-dependent poly(acrylic acid) complexation with phospholipid vesicles
Characterization of pH-dependent poly(acrylic acid) complexation with phospholipid vesicles
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DOI：
10.1006/jcis.1996.4608
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发表时间：
1997-01-01
影响因子：
9.9
通讯作者：
Baldeschwieler, JD
中科院分区：
文献类型：
--
作者：
Fujiwara, M;Grubbs, RH;Baldeschwieler, JD
聚（丙烯酸）（PAA）与磷脂（磷脂酰胆碱）囊泡的π-I依赖的络合，其特征在于通过荧光偏振，差示扫描量热法（DSC），和磷脂单分子膜的表面压力测量。络合显着低于pH 4时，聚合物的羧基被质子化，如所示的结合PAA囊泡和聚合物的流动性降低。络合作用在低聚合物浓度下较强，在较高聚合物浓度下较弱。PAA络合增加凝胶液晶（LC）相变温度（Tm）和焓（Δ H）的囊泡伴随着在过渡协同性下降。这很可能是由于PAA相互作用时磷脂头基的扰动。在磷脂/水界面处研究了聚合物吸附在磷脂表面上的效果。PAA渗透磷脂分子之间的能力作为pH的函数由单层在恒定表面压力下的侧向膨胀确定，聚合物渗透到单层中的能力随着pH值的降低而增加。这些结果表明PAA络合导致聚合物的膨胀。通过改变磷脂头基构象来改变囊泡的磷脂包装。(C)1997学术出版社
The pi-I-dependent complexation of poly(acrylic acid) (PAA) with phospholipid (phosphatidylcholine) vesicles was characterized by fluorescence polarization, differential scanning calorimetry (DSC), and surface pressure measurements of phospholipid monolayers. The complexation was pronounced below pH 4, when the polymer carboxyl groups are protonated, as shown by the binding of PAA to vesicles and the decrease in polymer mobility. The complexation was strong at low polymer concentrations and was weaker at higher polymer concentrations. PAA complexation increased the gel to liquid crystalline (LC) phase transition temperature (T-m) and enthalpy (Delta H) of the vesicles accompanied by a decrease in the transition cooperativity. This is most likely due to perturbations in the phospholipid headgroup upon PAA interaction. The effect of polymer adsorption on the phospholipid surface was investigated at the phospholipid/water interface, The ability of PAA to penetrate between the phospholipid molecules as a function of pH was determined by the lateral expansion of the monolayer at a constant surface pressure, The ability of the polymer to penetrate into the monolayer increased with decreasing pH. These results suggest that PAA complexation leads to expansion of the phospholipid packing of the vesicles by altering the phospholipid headgroup conformation. (C) 1997 Academic Press