Mechanical Properties of Immunoglobulin G and Albumin Monolayers

Abstract

The mechanical properties of protein films at the gas-water interface are determined by means of a mobile barrier. The films are subjected to extensional and compressional surface stresses and strains as opposed to the commonly used shear ones. Two proteins, immunoglobulin G and albumin, with distinctly different characteristics at the interface are investigated. The results from albumin films demonstrate the validity of this method and indicate that, in certain cases, only one measurement is required to completely characterize the elastic constants of the monolayer. From the viscoelastic properties observed for IgG between surface pressures of 3.5 and 26 mN/m, possible mechanisms to explain the film's behavior have been deduced.

Surface Elasticity and Viscosity from Oscillating Bubbles Measured by Automatic Axisymmetric Drop Shape Analysis

“…At higher surface pressures it seems that E 0 may increase again, but we were not able to compress the film further in the Langmuir balance. Such a behavior is often observed with monolayers of both synthetic and natural polymers (13,18,19). We see that the surface pressures at long times for the adsorbed films measured by this oscillating bubble method are around 20 mN m Ϫ1 and higher and that the extrapolated elasticity therefore may be expected to increase with increasing concentrations, as observed.…”

In-vitro sensing of biomechanical forces in live cells by a whispering gallery mode biosensor

“…The composition of the ECGM layer is unknown but seems to arise from proteins present in the ECGM supplement. Since proteins in question, such as serum albumin, show significantly higher Young's moduli (Ahluwalia et al, 1996;Brownsey et al, 2003) than the PE layer (Mermut et al, 2003), we decided to treat the adsorption layer as a single layer with the elastic properties of the PE film as the worst case estimate.…”