STRUCTURES OF LIPID AND BIOPOLYMER MONOLAYERS INVESTIGATED AS LANGMUIR-BLODGETT-FILMS BY ATOMIC-FORCE MICROSCOPY

The structures of lipid monolayers and biopolymers were investigated by atomic force microscopy (AFM). Collapsed films of different lipids were investigated as Langmuir-Blodgett films by using AFM. There were significant differences between various lipid films (Mg stearate, cholesterol, cholestane) in collapse state as investigated using AFM. These collapse states have been suggested to arise from the buckling of the monolayer. The Langmuir-Blodgett films of this state clearly reveal significant packing in this two-dimensional crystallization. Biopolymers (e.g. ovalbumin, hemoglobin, xanthan) were studied after adding to collapsed lipid films. It is shown here, for the first time in the literature, that biopolymer molecules can be studied by AFM under these conditions. The biopolymer structures were different for various proteins. Hemoglobin and ovalbumin were of different morphology than xanthan. Virus was found to exhibit a significantly different arrangement on the lipid films. In some cases, it was found that these differences could be related to protein-lipid interaction. The AFM procedure as delineated here, thus shows that this method can provide much useful molecular analyses of such mixed biopolymer molecules with collapsed lipid films.