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Studies of monolayer/substrate adhesion as function of the monolayer headgroup charge: DMPE and DMPA
Author(s) -
Engel Maria,
Riegler Hans
Publication year - 1991
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19910460157
Subject(s) - monolayer , adhesion , chemistry , work function , surface charge , charge density , substrate (aquarium) , analytical chemistry (journal) , layer (electronics) , chemical physics , organic chemistry , biochemistry , physics , oceanography , quantum mechanics , geology
Abstract The variation of the work of adhesion between lipid monolayers and a plane silicon oxide surface in a typical LB‐configuration is measured as function of the subphase pH. The adhesion energy is deduced via fluorescence microscopy from the equilibrium meniscus height. With increasing pH the negative headgroup charge of both, dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidic acid (DMPA) monolayers increases. The increasing charge of DMPE is reflected in a measured decrease of the work of adhesion at higher pH. The DMPA/SiO 2 interaction is not affected by increasing headgroup charges. These results are qualitatively understood in terms of an electrostatic double layer interaction between charged surfaces. It predicts decreasing adhesion for increasing, but low surface charge densities (DMPE). whereas the adhesion is constant for high surface charge densities (DMPA).