Nanoscale Study of DNA–Cu(2+) Interactions by Liquid-Cell Electron Microscopy

[Image: see text] Metal ions are indispensable constituent elements of the human body, among which Cu(2+) plays an important role in various biochemical reactions in the human body and is an essential element for maintaining human health. Studying the interaction between Cu(2+) and DNA can be helpful to further understand the mechanism of Cu(2+) behavior in organisms. In this paper, we investigated the DNA–Cu(2+) complex by transmission electron microscopy (TEM) and used in situ liquid-cell TEM to observe the dynamic processes of interactions between DNA and Cu(2+). Results show that the binding of Cu(2+) to DNA leads to the bending of the DNA strand and provides an anchor site for activating Cu(2+) for the nucleation and growth of copper crystals. Bound by the DNA strand, the copper crystals are arranged along the curved strand, showing the same arrangement pattern as guanine on the DNA sequence. It is believed that the study will further elaborate the interaction mechanism by directly observing the DNA–Cu(2+) complex at the nanometer scale and benefit the related biomedical research studies.