Skip over navigation

 

Electrostatic Actuation based Modulation of Binding Interaction between Protein and DNA Aptamer via Dynamic Force Spectroscopy

Xiao Ma (Iowa State University), Pranav Shrotriya (Iowa State University)

Experimental Nanobiomechanics

Mon 4:20 - 5:40

Barus-Holley 163

Seamless integration of artificial components with biological systems to form an elegant biotic-abiotic interface has promising application potential in biomedical engineering. One of the essential challenges is how to actuate or control the binding/dissociation behavior of biomolecules via external stimuli. The purpose of this investigation is to utilize Atomic Force Microscopy (AFM) to study the binding force between anti-coagulation protein thrombin and its binding pair DNA aptamer governed by electrostatic modulation. The thiolated aptamer was deposited onto gold substrate located in a liquid cell, and then repeatedly brought into contact with a thrombin-coated AFM tip under 0mV, 100mV and -100mV electrical fields respectively applied by a standard electrochemical cell. Force drop-offs during the pull-off process were measured to determine the unbinding force between the pair with loading rates spanning from 100pN/s to 40000pN/s. A large number of experiments were conducted to obtain statistically significant responses and dissociation forces associated with the last binding event were analyzed to understand the influence of electrical fields on molecular binding. The results from experiment show that the specific binding events of the pair were inhibited under the positive electrical fields. Due to the negatively charged nature of DNA aptamer, positive electrical fields can trigger large bending-down conformational transition of the strands, thus can inhibit the bond formation. There is no harmful influence on the molecular binding by negative electrical fields. The autocorrelation function analyses were conducted on all three cases for obtaining the elementary dissociation force, and showed that the specific binding maintain the same scale and nature of the force. The study confirms the idea of electrostatic modulation of the binding interaction between thrombin and DNA aptamer, thus proposes an application potential on biotic-abiotic interface design.