Adhesion Induced DNA Naturation

TL;DR

This paper models DNA adsorption and naturation as interacting polymers near a surface, revealing conditions under which DNA remains naturated and adsorbed, and constructing a phase diagram of these states.

Contribution

It introduces a variational model showing how combined weak surface and binding potentials can induce DNA naturation and adsorption, which was not previously understood.

Findings

Adsorption reduces entropy gain, affecting naturation.

Weak potentials can still induce a naturated adsorbed phase.

Phase diagram delineates conditions for naturation and adsorption.

Abstract

DNA adsorption and naturation is modeled via two interacting flexible homopolymers coupled to a solid surface. DNA denatures if the entropy gain for unbinding the two strands overcomes the loss of binding energy. When adsorbed to a surface, the entropy gain is smaller than in the bulk, leading to a stronger binding and, upon neglecting self-avoidance, absence of a denatured phase. Now consider conditions where the binding potentials are too weak for naturation, and the surface potential too weak to adsorb single strands. In a variational approach it is shown that their combined action may lead to a naturated adsorbed phase. Conditions for the absence of naturation and adsorption are derived too. The phase diagram is constructed qualitatively.