ELECTROSTATIC NANOTITRATION OF WEAK BIOCHEMICAL BONDS

We introduce a new method to measure the energetics and range of weak biochemical bonds using functionalized vesicles. Large bilayer regions are held in molecular proximity by osmotic depletion forces to enable rapid specific bonding. By fixing an electrical charge to the tetheri ng site of the functional group on one surface, persistent adhesion of the vesicles after removal of the depletion stress is titrated agains t the clamped electrostatic potential of the opposite surface. We demo nstrate the method with DNA bases and obtain new information on the ra nge of their specific interactions.