Adsorbed Layers of Storage Protein from Aleurone Cells of Barley at Different Surfaces Studied by Atomic Force Microscopy

Maria Tomoaia-Cotisel

Babes-Bolyai University of Cluj-Napoca, Faculty of Chemistry and Chemical Engineering, Physical Chemistry and Biophysics Department, 400028 Cluj-Napoca, Romania



Self-assembled layers of storage globulin protein from aleurone cells of barley (Hordeum vulgare L.) were studied by protein adsorption from aqueous saline solutions, as function of ionic strength and pH, on solid support, e.g. glass and mica, and by tapping mode atomic force microscopy (AFM). Alternatively, the protein adsorption on lipid films (e.g., dipalmitoyl phosphatidyl choline: DPPC or stearic acid:SA) at the air/water interface, which were finally transferred to solid supports by Langmuir-Blodgett technique (LBT), was also investigated by AFM. The behavior of protein is complex generating large colloidal particles which appear to adsorb monotonically on the solid surfaces. The protein layer shows a unique structural pattern in its adsorbed state that might laid down during grain development and it can generate complex supramolecular structures involving various classes of biological molecules, e.g., lipids, natural pigments or combination of those. The obtained results indicate a long range order within protein, protein:DPPC and protein:SA layers, as well as electrostatic effects, intermolecular repulsion and surface-protein attraction. Due to the high stability of protein layers, the storage protein might fulfill the key requirement as building blocks for the production of novel supramolecular materials and nanoscale devices as required in molecular nanobiotechnology and biomimetics.