Despite the importance of surface-bound biomolecules in biology and, increasingly, in biotechnologies, our understanding of the extent to which and mechanisms by which biomolecules interact with specific surfaces remain quite limited. In response, we have used a novel electrochemical method to experimentally measure the change in folding free energy that occurs when a simple DNA structure is attached to a number of chemically distinct, highly charged surfaces. Not surprisingly, the magnitude of the observed perturbation depends strongly on the charge of the surface, with increasingly negatively charged surfaces leading to increased destabilization. Conversely, attachment to a positively charged surface renders the folding of this negatively charged biomolecule irreversible. A simple model that considers only the excluded volume and electrostatic consequences of attachment quantitatively recovers the observed free energy on negatively charged surfaces as a function of charge and ionic strength, thus highlighting the important role that surface‑biopolymer electrostatics can play in the physics of surface attached biomolecules.

Entropic and electrostatic effects on the folding free energy of a surface-attached biomolecule: An experimental and theoretical study

249th National Meeting (2015)

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