Study of the pH sensitive DNA motor


General Introduction


I-motif is a 4-strands-helix (tetraplex) DNA secondary structure which could be formed by sequences with multiple continuous cytosins in slightly acidic circumstances. pH dependence offers an opportunity to control the statement of the DNA strand and actuate it as a motor through acidity variation.


Driven Methods               

item1.jpg item2.jpgitem3.jpg            

We have successfully driven the folding & unfolding of i-motif structure via the alternate addition of acid and base, via UV light, and via electricity. Following the evolution, this DNA motor can now work robustly, efficiently and automatically with noncontact energy input. Further innovations and improvements of the motor driven methods are expected.


Mechanical & Dynamic Study                       item4.jpg item5.jpg

Single molecular force spectroscopy, including AFM and magnetic tweezers, has been used to study the mechanical information of the DNA motor with Pico Newton resolution. Additionally, the kinetic and thermal-dynamic behaviors of i-motif motor are studied using optical spectroscopy. Besides their theoretical significances, these researches can also give directions to the application of this DNA motor.



With the pH dependence and the remarkable distinction between tetraplex and duplex, i-motif motor has been used to control the distance between objects in nanometer scale. We have used this motor to construct smart surfaces with controllable wettability, charge density, surface tensity and photo-electricity. We also realized a pH controlled DNA tweezers and the pH induced revisable aggregation of gold nanoparticles. It is believable that much more tasks which need variable distances in nano world could be facilitated by this DNA motor system.