Single-molecule AFM characterization of individual chemically tagged DNA tetrahedra
Sprache des Titels:
Englisch
Original Kurzfassung:
Single-molecule characterization is essential for ascertaining the structural and
functional properties of bottom-up DNA nanostructures. Here we enlist three atomic force
microscopy (AFM) techniques to examine tetrahedron-shaped DNA nanostructures that are
functionally enhanced with small chemical tags. In line with their application for biomolecule
immobilization in biosensing and biophysics, the tetrahedra feature three disulfide-modified vertices
to achieve directed attachment to gold surfaces. The remaining corner carries a single bioligand that
can capture and present individual cargo biomolecules at defined lateral nanoscale spacing. Highresolution
AFM topographic imaging confirmed the directional surface attachment as well as the
highly effective binding of individual receptor molecules to the exposed bioligands. Insight into the
binding behavior at the single-molecule level was gained using molecular recognition force
spectroscopy using an AFM cantilever tip with a tethered molecular receptor. Finally, simultaneous
topographic and recognition imaging demonstrated the specific receptor-ligand interactions on
individual tetrahedra. In summary, AFM characterization verified that the rationally designed DNA
nanostructures feature characteristics to serve as valuable immobilization agents in biosensing,
biophysics, and cell biology.