We measured the absorbance shift to confirm that the concentration of cis- azobenzene increases according to the amount of UV exposure, and that the concentration of DNA signal increases accordingly.
Generally, the maximum absorbance of DNA is 260nm, and its molar extinction coefficient decreases on base pairing. So, according to the Beer's law, the absorbance of DNA increases when its double strand becomes single strands.
On the other hand, azobenzene has absorption at the wavelength of 350nm when it is in trans-form, and 440nm when in cis-form. Therefore, by observing the changes in these three wavelengths, one can see whether the DNA complex is dissociated by the isomerization of azobenzene.
We performed UV irradiation on azobenzene-introduced “UV-DNA converter” and measured the absorbance of each wavelength on each irradiation time. Thus, we confirmed the dissociation of azobenzene in cis-form, and the binding of it in trans-form.