Most characterization studies of lipids have focused on single phospholipid monolayers on mica. Very few have investigated mixed phospholipid monolayers. In this study, nanomorphology of mixed phospholipid monolayers have been evaluated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) techniques. The mixed phospholipid monolayers were drop-casted on two different substrates that are mica and gold. Binary phases of DPPC/DPPG, DOPC/DOPG, and POPC/POPG were used as mixed phospholipid monolayers. The characterization of mica and gold substrates showed major differences between AFM and FE-SEM images. Contrary to FE-SEM, AFM images showed that mica substrate is relatively flat while gold substrate used in this study has a high roughness value and contained some microvalleys. Overall, there is good agreement in information about the two very different imaging techniques when analyzing the monolayers on the two substrates. AFM and FE-SEM showed the size and shape of the particles, and presence of microdomains. The basal planes and edges of monolayers on gold are better resolved with FE-SEM. AFM revealed the presence of line defects at their surface, which might correspond to a border between different domains. AFM images give more detailed information on the roughness of the surfaces. Both techniques combine to improve the characterization of nanoscale structures of phospholipids and provide information about shape and morphology (AFM), dimensions (AFM and FE-SEM), and surface properties (AFM).<br/>

Comparative atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) studies of mixed phospholipid monolayers

249th National Meeting (2015)

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