There are several LY294002 proposed drug-loaded immunoliposome formulations that are used

in drug delivery applications [5–8], but there is still scant knowledge on how liposomes interact with the antibodies they incorporate [9, 10]. With the view of investigating interactions between liposomes and antibodies, we first set out to study the interactions between fatty acids and proteins by the Langmuir-Blodgett technique. Langmuir monolayers are widely used to model the biological membrane surface in studies to understand the structure and function of biological membranes and the protein-lipid interactions [11]. The way proteins assemble on the lipid bilayer, either partially or fully embedded, and their ensuing stability should be considered before any experiment on the incorporation of proteins in the membrane is performed [12,

13]. In 1972, Singer and Nicolson made the important distinction between integral and peripheral membrane proteins in the fluid mosaic model of biological membranes [14]. Lipid-protein interactions that occur in the binary mixed system can be studied from data on miscibility, compressibility and thermodynamic stability from the isotherms obtained [15]. The analysed data would give an insight into KPT-330 intermolecular interactions between the lipid and protein, thereby providing useful information on the different ways proteins associate with cell membranes. In our study, we used stearic acid (SA) to create a monolayer mimicking a half bilayer membrane, with various concentrations of bovine serum albumin (BSA) incorporated onto the monolayer. BSA is a globular protein that is highly water soluble and readily available at low cost. Its structural similarity to the human homologue makes it a widely studied protein [16]. To the best of our knowledge, the behaviour of BSA Bacterial neuraminidase in a mixed lipid monolayer has not been studied in any great detail. The outcome of this initial study would provide indicators for future work on the interactions of other globular proteins, including antibodies,

in a mixed lipid monolayer. Methods Materials A spreading solution of stearic acid (Sigma-Aldrich, Palo Alto, CA, USA) was prepared by RAD001 dissolving it in analytical grade chloroform (Merck, Whitehouse Station, NJ, USA). Various concentrations of bovine serum albumin (Carl Roth GmbH, Karlsruhe, Germany) were prepared by dissolving in distilled water. Double-distilled water (processed by NANOpure Diamond Ultrapure Water System, Barnstead International, Dubuque, IA, USA) was used as the subphase throughout the study. Langmuir monolayer/mixed monolayer measurements A computer-controlled Langmuir balance (KSV 5000, Langmuir System, Helsinki, Finland) equipped with symmetric barriers and Teflon trough (total area 60,720 mm2) was used to determine the surface pressure (π)-molecular area (A) isotherms. The surface pressure of the films was measured to an accuracy of ±0.1 mN m-1 using a flame-cleansed high-purity platinum metal Wilhelmy plate (19.