DNA Origami Fiducial for Accurate 3D Atomic Force Microscopy Imaging

Atomic force microscopy
(AFM) is a powerful technique for imaging
molecules, macromolecular complexes, and nanoparticles with nanometer
resolution. However, AFM images are distorted by the shape of the
tip used. These distortions can be corrected if the tip shape can
be determined by scanning a sample with features sharper than the
tip and higher than the object of interest. Here we present a 3D DNA
origami structure as fiducial for tip reconstruction and image correction.
Our fiducial is stable under a broad range of conditions and has sharp
steps at different heights that enable reliable tip reconstruction
from as few as ten fiducials. The DNA origami is readily codeposited
with biological and nonbiological samples, achieves higher precision
for the tip apex than polycrystalline samples, and dramatically improves
the accuracy of the lateral dimensions determined from the images.
Our fiducial thus enables accurate and precise AFM imaging for a broad
range of applications.