Interaction of polyacrylic acid with phosphatidylcholine bilayer membranes in slightly acidic mediumстатья
Информация о цитировании статьи получена из
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Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Interaction of polyacrylic acid with lipid membranes composed of zwitter-ionic phosphatidylcholine has been studied. It was shown that under neutral conditions, polyacrylic acid did not interact with liposomes composed of egg yolk lecithin, while under slightly acidic conditions (pH < 4.5) adsorption of the polymer was observed. About 70% of the polyacid was adsorbed on liposomes, as far as its excess increased up to 1.5-fold. Adsorption of the polymer was accompanied by formation of vesicle aggregates, as assessed by photon correlation spectroscopy. Interaction of polyacrylic acid with vesicles under slightly acidic conditions resulted in permeabilization of liposome membranes, detected by two independent methods: (1) leakage of fluorescent probe pyranine placed in the internal compartment of liposomes and (2) leakage of N-benzoyl-L-arginine (BAEE), a substrate of proteolytic enzyme trypsin. The former was followed by measuring the fluorescent intensity of the probe, which decreased due to the escape from slightly basic environment of liposomes into acidic external solution. In the latter case, an addition of trypsin into the external solution allowed control of BAEE leaking by potentiometric titration of the acid produced in the external solution due to enzymatic hydrolysis of the substrate escaping from the vesicles. The electrostatic nature of polymer-membrane interactions was confirmed by the addition of low molecular weight electrolyte resulting in the diminishing of the vesicle aggregation in the presence of the polyacrylic acid. At the same time, the polymer effect on the membrane permeability could not be explained only by the formation of electrostatic bonds with the vesicle surface. It has been demonstrated that the addition of dipole modifier phloretin resulted in substantial decrease in the polymer effect on membrane permeability. This fact suggests that dipole potential of the bilayer is an important factor favoring a deepening of the polymer in the hydrophobic core of the membrane and, thus, formation of pores or channels in the bilayer.