Fig. 3
From: Advances in aptamer screening and aptasensors’ detection of heavy metal ions
A, B At low concentration of Cd2+, the thickness increases and the density decreases with the increase of mass load. It is speculated that the binding of Cd2+ to aptamer is mainly through the binding of phosphate group. C, D At high concentration of Cd2+, the thickness decreases and density increases with increased load. It is speculated that Cd2+ leads to the conformational transformation of DNA through the π-π stacking of bases [104]