IN-SITU OBSERVATION OF PROTEIN-ADSORBED STEARIC-ACID MONOLAYER BY BREWSTER-ANGLE MICROSCOPY AND FLUORESCENCE MICROSCOPY

A fluorescence probe, fluorescein isothiocyanate (FITC), was introduce d to proteins, and the morphology of protein-adsorbed stearic acid mon olayer was observed by fluorescence microscopy and Brewster angle micr oscopy (BAM) in order to analyze images. At a low protein concentratio n, the surface pressure increased as shown by a sigmoidal curve. A num ber of stripe patterns in the BAM images increased and the shapes beca me clear with increasing concentration of proteins. Simultaneously, th e size of circular islands also became small, and finally disappeared. These results suggest that the very large stripe patterns in the BAM image show the assembly of both proteins and stearic acid molecules, a nd small circular islands show only the stearic acid molecules. (C) 19 98 John Wiley & Sons, Ltd.