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Investigations of DPPC effect on Al2O3 particles in the presence of (phospho)lipases by the zeta potential and effective diameter measurements

Authors :
Wiącek, Agnieszka Ewa
Source :
Applied Surface Science. Feb2011, Vol. 257 Issue 9, p4495-4504. 10p.
Publication Year :
2011

Abstract

Abstract: Adsorption of phospholipid (DPPC) from NaCl electrolyte solution (or from chloroform solution) on Al2O3 particles in suspension was investigated by means of the zeta potential and effective diameter measurements as a function of pH using dynamic light scattering. Al2O3 particles were precovered with an amount of dipalmitoylphosphatidylcholine sufficient to cover the alumina surface by the statistical mono- or bilayer (ML or BL). It was found that DPPC from NaCl solution was adsorbed on Al2O3 surface independently of phospholipid concentration, which resulted in decrease of the initial zeta potential of Al2O3 suspension. When alumina was precovered with DPPC from chloroform (ML or BL) some reorientation of phospholipid molecules could take place. Despite the lowering of the zeta potential value in both cases (from both aqueous and chloroform solution) DPPC stabilized the Al2O3 particle aggregates, which resulted in smaller and smoother changes of the aggregate size during 2-experiment hours due to steric and electrostatic stabilization. In the next series of experiments the effect of enzymes (phospholipase A2 or lipase Candida cylindracea) on the behavior of Al2O3/DPPC particles was studied. The kind of the enzymes, the hydrolysis products, which were palmitic acid and lysophosphatidylcholine (or glycerylphosphorylcholine), and pH changed the suspension zeta potential and influenced the stability of these systems. Lipase was found to be a more active enzyme than phospholipase. The electrokinetic parameters connected with the adsorption process and resulting from the enzyme action seem to be helpful for characterization of the Al2O3/DPPC suspension and the activity of the enzymes, which is discussed in the paper. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
01694332
Volume :
257
Issue :
9
Database :
Academic Search Index
Journal :
Applied Surface Science
Publication Type :
Academic Journal
Accession number :
57514705
Full Text :
https://doi.org/10.1016/j.apsusc.2010.12.106