Modified AFM System for Direct Investigation of Elastic Properties of Single Molecules

Arkadiusz Ptak, Seiji Takeda, Chikashi Nakamura, Jun Miyake

TERC, AIST, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan

Masami Kageshima, Suzanne P. Jarvis, Hiroshi Tokumoto

JRCAT, 1-1-4 Higashi, Tsukuba, Ibaraki 305-8562, Japan

The knowledge and examination of elastic properties of single molecules, especially polymer molecules, become an important element in nanotechnology and biochemistry.
We propose a novel experimental method for estimation of stiffness and elastic modulus of a single molecule: a direct mechanical test using a modified AFM system. For this purpose a self-assembled monolayer built from two kinds of peptides: reactive (able to anchor to the AFM tip) and non-reactive was synthesized. In a typical experiment a single peptide molecule was stretched between a substrate and the AFM tip. The amplitude of the cantilever oscillation due to a magnetic force applied to the cantilever was recorded and recalculated into stiffness of the stretched molecule. The obtained values of longitudinal Youngｹs modulus for various peptides seem to be reasonable comparing them to the Youngｹs modulus of protein crystals and linear organic polymers.