Professor Hak-Sung Kim and Yiseul Ryu, a Ph.D. student, both from the KAIST Department of Biological Sciences have developed a new method of constructing magnetic nanoparticle clusters (NPCs) using DNA-binding zinc finger (ZnF) proteins. The research was published on the online edition of Angewandte Chemie International Edition.

NPCs are clusters of nanoparticles such as magnetic nanoparticles, gold nanoparticles, and quantum dots. Their diameters range from one to 100 nanometers (nm). NPCs exhibit different group behaviors from single nanoparticles, a phenomenon that has gathered interest from researchers.

Specifically, NPCs and single nanoparticles have different optical and physical characteristics such as plasmon absorbance, energy transfer between particles, electron transfer, and conductivity. These characteristics allow NPCs to be used in bio and medical fields as well as nanoelectric or nanoplasmon devices.

For the NPCs to exhibit their unique characteristics, the cluster size and composition have to be controlled precisely. However, conventional methods have relied on chemical bindings, which required complicated steps rendering precise control very difficult.

To overcome such obstacles, Professor Kim and his research team turned his attention to ZnF proteins. ZnF proteins have zinc ions that bind specifically to a DNA sequence. Constructing NPCs using ZnF proteins is more biocompatible and allows for better control over the size and composition.

Professor Kim and his research team confirmed their findings with three different samples, which had DNA with varying lengths. The resulting NPCs had different sizes and shapes depending on the length of DNA used.

The constructed magnetic NPCs showed that the T2 relaxation rate was three times that of Feridex, a contrast media for magnetic resonance imaging (MRI). This result shows that magnetic NPCs can be utilized in MRI contrast media, fluorescence imaging, and drug delivery.

Professor Kim’s research has shown a new method of constructing supramolecular assemblies consisting of inorganic nanoparticles using the binding characteristics of DNA and protein. The newly developed method is expected to be applied in medical diagnosis, imaging, as well as drug and genome delivery.

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