Maximum pull out force on DNA hybrids

Abstract

We discuss theoretically the force F between two colloidal particles, each of them carrying one single strand DNA. The two strands are complementary only on a finite sequence of (ℓ) consecutive base pairs. We define an adjustment length ϰ⁻¹ (a few base pairs); in the adjustment regions near both ends of the paired region, the tension is still mainly on one single strand. But in the central part (for ℓ>ϰ⁻¹) the two backbones are equally loaded. This leads to a rupture force F_c increasing linearly with ℓ for ℓϰ<1, and saturating for ℓϰ>1.