Analytical descriptions of dynamic force spectroscopy: behaviour of multiple connections Original Research Article

Exploration of the stressed lifetime of a single bond can reveal details of hidden transition states along the unbonding coordinate [Faraday Discuss. 111 (1998) 1]. Such experiments with single molecules are, however, not easy. To measure the force between two molecules requires manipulation of the contact so that two and only two molecules interact. This is achieved by reducing the probability of bond formation on contact through the control of surface chemistry, molecular density, contact force and time. When the contact area and surface chemistry cannot be controlled multiple interactions may dominate. The fundamental question arises whether quantitative information pertinent to the single interaction can be extracted from measurements of multiple simultaneous detachments. Various statistical methods have been adopted in an attempt to elucidate the single-molecule event from the rupture of multiple attachments [Biophys. J. 70 (5) (1996) 2437; Biochemistry 36 (24) (1997) 7457; Langmuir 12 (5) (1996) 1291]. Here, I aim to qualify and validate, if possible, such approaches. Whilst the analysis shows that the dynamics of loading multiple attachments precludes an accurate inference of the single unbinding event, the complexity in behaviour could be exploited to construct materials with novel dynamic mechanical properties.