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

The structures of lipid monolayers and biopolymers were investigated b y atomic force microscopy (AFM). Collapsed films of different lipids w ere investigated as Langmuir-Blodgett films by using AFM. There were s ignificant differences between various lipid films (Mg stearate, chole sterol, 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 s ignificant packing in this two-dimensional crystallization. Biopolymer s (e.g. ovalbumin, hemoglobin, xanthan) were studied after adding to c ollapsed lipid films. It is shown here, for the first time in the lite rature, that biopolymer molecules can be studied by AFM under these co nditions. The biopolymer structures were different for various protein s. Hemoglobin and ovalbumin were of different morphology than xanthan. Virus was found to exhibit a significantly different arrangement on t he lipid films. In some cases, it was found that these differences cou ld be related to protein-lipid interaction. The AFM procedure as delin eated here, thus shows that this method can provide much useful molecu lar analyses of such mixed biopolymer molecules with collapsed lipid f ilms.