Organic Biomaterial with a Structure Controllable by Coin Magnets Developed
Professor Yong-beom Lim’s research team develops organic biomaterial with a structure controllable by coin magnets
Published in Nature Communications
The research team led by Professor Yong-beom Lim from the Department of Materials Science and Engineering at the College of Engineering has developed a self-assembling organic material with a nanostructure controllable with magnetic fields and an artificial chromosome with controllable DNA coating and release via magnets.
Self-assembling materials with structures controllable by magnetic fields can be utilized in data storage devices, intelligent DNA/mRNA gene therapies and vaccines, medical molecular imaging systems, and nanorobots. Most existing magnetically responsive self-assembling materials use paramagnetic or ferromagnetic metallic elements. DNA and certain proteins are known as magnetically responsive and purely organic compounds. However, as their sensitivity is considerably small, a special magnetic field generator emitting at least several Tesla is necessary. Expensive and massive equipment is required to generate such a strong magnetic field. In this context, the research team has developed the world’s first purely organic compound based on peptides, whose self-assembling structure can be altered even with coin-shaped magnets used in daily life.
As self-assembling materials, peptides are easy to synthesize, capable of realizing various structures and functions, and biocompatible. Specifically, among the secondary structures of peptides, the alpha-helix performs essential functions in the body, has rigid structural properties, and can be arranged by a magnetic field. Nevertheless, most alpha helices are stabilized only within protein structures; if they are isolated, the helix structure unwinds. Existing alpha helices that are stable even when isolated carry charges, making them unsuitable for the hydrophobic part of self-assembling molecules.
To develop a magnetically responsive self-assembling organic material, the team first developed an “MNP-helix” (monomeric nonpolar perfect alpha-helix), a nonpolar molecule that maintains a perfect alpha-helix structure even when it is a single molecule in aqueous solution. This MNP-helix was applied to the rod regions of rod-coil self-assembling building blocks. The rod-coil building blocks comprise a rigid hydrophobic rod region and a flexible hydrophilic coil region. The self-assembly behavior varies with the structural properties, such as the ratio of the rod to the coil, and chemical properties, including hydrophobicity and hydrophilicity. To control self-assembly through an external magnetic field, a balance between the force that drives the molecule to self-assemble due to hydrophobic interactions and that by which the MNP-helix rod responds to the magnetic field is critical. As the alpha-helix rod lengthened, the magnetic responsiveness improved. However, if it became too long, the hydrophobic interactions became extremely strong, weakening the self-assembly’s magnetic responsiveness.
The team developed an artificial chromosome by forming a complex with DNA using the magnetically responsive self-assembling organic material peptide they created. The artificial chromosome was assembled in stages. The electrostatic attraction between the peptide and DNA and the hydrophobic interactions among the peptides cooperatively formed a robust nanoribbon structure. Multiple layers of nanoribbons grew to form a larger structure, constituting the artificial chromosome, which effectively protected the DNA inside from degradative enzymes.
Rotating a magnet around the artificial chromosome, the team separated the DNA and peptide, restoring the DNA strands. DNA naturally tends to align perpendicular to the magnetic field, while peptides tend to align parallel to it, resulting in the disassembly of the DNA-peptide complex and the release of the DNA strand.
This study presented a new perspective—the self-assembling structure of organic materials can be controlled by a magnetic field using the newly developed alpha-helix peptide (MNP-helix)-based self-assembling organic material. It is expected to stimulate the development of various magnetically responsive self-assembling organic materials and investigations into the magnetic control methods of self-assembling organic materials.
Furthermore, the successful development of an artificial chromosome that coats, compresses, and protects DNA and restores DNA through a magnetic field is expected to affect various applied research fields, including the development of DNA memory and DNA/mRNA gene delivery systems.
This study was published in the globally renowned academic journal Nature Communications (IF 17.694) on May 29 2023, with You-jin Jung and Hyoseok Kim as co-first authors and Professor Yong-beom Lim as the corresponding author.
Professor Jong-Hyun Ahn
Professor Seong Chan Jun
Professor Donghyun Kim