Molecular-scale investigations of structures and surface charge distribution of surfactant aggregates by three-dimensional force mapping.

摘要: Surface charges on nanoscale structures in liquids, such as biomolecules and nano-micelles, play an essentially important role their structural stability well chemical activities. These interact with each other through electric double layers (EDLs) formed by the counter ions electrolyte solution. Although static-mode atomic force microscopy (AFM) including colloidal-probe AFM is a powerful technique for surface charge density measurements EDL analysis submicron scale precise single-nanometer resolution has not been made because of its limitation detection sensitivity. Here we demonstrate molecular-scale self-assembled micellar structures, molecular hemicylinders sodium dodecyl sulfate (SDS), three-dimensional (3D) mapping based frequency modulation AFM. The SDS hemicylindrical diameter 4.8 nm graphite were clearly imaged. We have succeeded visualizing 3D forces hemicylinder surfaces obtaining first time. results showed that trench regions between was much smaller than tops. method can be applied to wide variety local distribution studies, spatial variation single protein molecule.