Study of the pH sensitive DNA motor
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.
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
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.