Atomic Force Microscopy Study of the Texture of Condensed Phase Domains in 1-Monostearoylglycerol Monolayers

Abstract

Atomic force microscopy (AFM) in friction mode is successfully used for probing the inner structure of condensed phase domains of 1-monostearoylglycerol (MSG) monolayers transferred from the air-water interface onto mica, glass, and silicon wafers by the Langmuir-Blodgett (LB) technique. The friction anisotropy reveals the same 7-fold domain substructure as observed at the air-water interface by Brewster angle microscopy (BAM). It is caused by differences in the tilt orientation of the molecules within the domain segments. After deposition of the monolayer, the main features of the condensed phase morphology, such as size, shape, and azimuthal tilt, are preserved independent of the solid substrate. The widths of the straight segment lines were found to be <100 nm. This result supports the idea that the segment boundaries of amphiphilic monoglycerol domains are low-energy lattice rows. Differences in the smoothness of the domain boundary at the air-water interface and on solid substrates can be caused by changes in the energetic conditions along the three-phase contact line.

Interaction of the cationic peptide bactenecin with mixed phospholipid monolayers at the air–water interface

“…Maine et al also showed by GIXD experiments there were not important structural differences when monoglycerol monolayers in the condensed phase were transferred to mica, glass, and silicon wafers by the Langmuir-Blodgett technique provided that their main features such as domain size, shape, and azimuthal tilt were preserved independently of the solid substrate. Consequently, the lateral interaction between the amphiphilic molecules dominates in the condensed monolayer phase and possible interactions with substrates are of minor importance [67]. Also, recently Dorosz et al [68] performed similar experiments to those here reported.…”

“…As observed in Fig. 4e and f, some line defects are observed as a consequence of the differences in domain boundaries, probably originated from the affectation of the three-phase contact line upon monolayer transfer [67].…”

Effect of interfacial molecular recognition of non-surface-active species on the main characteristics of monolayers

“…For this purpose, the surface film prepared in the same way as for the BAM studies after the formation of large domains was transferred onto a silicon wafer. In previous work, it was shown that all main feature of the domain are preserved on the solid substrate [47]. The AFM image of Fig.…”

Rheological Characterization, Crystallization, and Gelation Behavior of Monoglyceride Gels

“…From thereon, the molecules can easily fall to the lower state of energy of the β-crystalline packing. An alternative could be that within the monolayer domains of crystalline arrays occur, as has been demonstrated clearly for saturated monoglyceride to grow on the water/air interface (19).…”