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Rupture Event Scanning (REVS) is applied for the first time within an approach based on dynamic force spectroscopy. Using model DNA duplexes containing 20 pairs of oligonucleotides including those containing single mismatches, we demonstrated the possibility of reliable determination of the kinetic parameters of dissociation of biomolecular complexes: barrier positions, the rate constants of dissociation, and the lifetime of complexes. Within this approach, mechanical dissociation of DNA duplexes occurs according to a mechanism similar to unzipping. It is shown that this process takes place by overcoming a single energy barrier. In the case where a mismatch is located at the farthest duplex end from the QCM surface, a substantial decrease in the position of the barrier between the bound and unbound states is observed. We suppose that this is due to the formation of an initiation complex containing 3-4 pairs of bases, and this is sufficient for starting duplex unzipping.

Measurement of the forces of unwinding of DNA double helix was conducted. Silicon wafers were chosen as substrates. It is demonstrated that the use of gold for surface modification causes the bimodal probability distribution of rupture forces because of the surface roughness. Surface modification with the help of Langmuir–Blodgett procedure is proposed as an alternative. The use of this method gives unimodal distribution of rupture forces. The forces of double helix unwinding are reported for oligonucleotides containing 20 base pairs depending on salt concentration. Furthermore, forces for the shear mode and unzipping mode are measured.