Miscibility of Lipids in Monolayers Investigated through Adsorption Studies of Antibodies

Abstract

The miscibility and reactivity of binary monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoglycolipoate (DPPGL) and 1-palmitoyl-2-(16-(S-methyldithio)hexadecanoyl)-sn-glycero-3-phosphocholine (DSDPPC) have been studied. The morphology of the binary monolayers transferred on a gold substrate at different surface pressures was determined by scanning probe microscopy (SPM) and compared with the interfacial properties of the films at the air/water interface. Specific immobilization of pepsin-cleaved antibody Fab′ fragments from a Langmuir film onto a solid-supported DSDPPC-DPPGL (95:5 mol %) monolayer was utilized in the visualization of the miscibility and reactivity of the mixed lipid monolayers. The protein immobilization was shown to be dependent on the degree of condensation of the DSDPPC-DPPGL film. Furthermore, the linker molecules were shown to be favorably orientated for cross-linking reaction when amidst liquidcondensed domains of the matrix molecules. A closer look at the Fab′ domains revealed, however, that the domains were not fully covered with antibodies. The lower than expected relative surface density (RSD) of the Fab′ fragments was believed to be mainly due to random orientation of the Fab′ fragments at the air-water interface, which prevented part of them from participating in a thiol-disulfide interchange reaction between the antibodies and the linker molecules.

Adsorption of pepsin in octadecylamine matrix at air–water interface

“…This observation indicates that the interaction between PEP and ODA is very strong. The two-dimensional surface compressibility analysis of the Langmuir monolayer is performed to understand the presence as well as details of phase transition [32][33][34][35][36]. The compressibility coefficient (β) is calculated using the following equation [32].…”

Incorporation of ovalbumin within cationic octadecylamine monolayer and a comparative study with zwitterionic DPPC and anionic stearic acid monolayer

“…We have performed the two-dimensional surface compressibility analysis of the Langmuir monolayer to understand the details of phase transition [42][43][44][45][46]. The compressibility coefficient (β) is calculated using the following equation [42]:…”

Interaction of N-nitrosodiethylamine/bovine serum albumin complexes with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine monolayers at the air–water interface

“…The presence of mixtures in phospholipid monolayers [16] and some adsorbed macromolecules in stearic acid and cholesterol monolayers [22] produce more compressible monolayers, depending on the molecular size and the hydrophobicity of the molecules.…”

“…Some authors [16,17] prefer the use of C s because of the ease of identifying the middle of the liquid expanded (LE)-liquid condensed (LC) phase coexistence; others use C −1 s to identify the onset of the LE-LC equilibrium phase transition [13,18,19]. In this work we use the compressional modulus to analyze the protein adsorption from the bulk into 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers at the air/water interface.…”