Three sizes of colloidal gold particles are available in a convenient kit form. The kit contains 8 numbered 15mm AFM discs with mica attached for calibration and tip characterization. Remaining colloidal gold can be used for coadsorption with biomolecules or other samples.
Vesenka J, Manne S, Giberson R, Marsh T, and Henderson E, 1993. Colloidal Gold Particles as an Incompressible Atomic Force Microscope Imaging Standard for Assessing the Compressibility of Biomolecules. Biophysical Journal 65:1-6
ABSTRACT Colloidal gold particles have multiple uses as three-dimensional atomic force microscopy imaging standards because they are incompressible, monodisperse, and spherical. The spherical nature of the particles can be exploited to characterize scanning tip geometry. As uniform spheres, colloidal gold particles may be used to calibrate the vertical dimensions of atomic force microscopy at the nanometer level. The monodisperse and incompressible nature of the gold can be used to characterize the vertical dimension of coadsorbed biomolecules.
Simultaneous measurements of gold with tobacco mosaic virus show that, at the same applied vertical force, the tobacco mosaic virus is undamaged by blunt tips but is compressed or disintegrated under sharper scanning styli, suggesting that specimen degradation is partly a pressure-dependent effect.