The nucleating core of the Amyloid p peptide implicated in Alzheimer's disease, when formulated as Ac-KLVFFAE-NH2 (Ap( 16-22)), self-assembles in aqueous environments as peptide bilayers maintaining a thickness similar to biological phospholipid membrane [2]. The hydrogen-bonded peptides are arranged in antiparallel out-of-register p-sheets and stacks of these sheets make up one of the leaflets of the bilayer membrane[2]. The TV-terminal lysine residues are exposed on the surface of each leaflet with its backbone amide not incorporated into the hydrogen-bonding network [31. These structural models [3] for AP(16-22) and its congener E22L present ordered crystalline structures with a high density of alkyl ammonium ions located at precise positions across a nanoscale grid on a hollow nanotube surface. Methods for mapping these charges in aqueous solutions to define positions of macromolecular adsorbents, surface imperfections, domain size, and even surface dynamics are limited [4-6]. However, extensions of Atomic Force Microscopy (AFM), by applying a bias on the probe tip, have been developed to measure the electric field gradient distribution above dry surfaces, including mineral crystal faces, graphene layers and other solid materials [7]. Here we demonstrate electrostatic force microscopy (EFM) analyses (Figure 1) that map the
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