Researchers at the University of Missouri discovered a way to draw tiny patterns on living cells without hurting them. They used a method called ice lithography. Lithography is a process that creates small designs, often for computer chips. Traditional lithography uses liquids that can damage fragile materials like cells or carbon nanotubes.
This research is published in Nano Letters. The Missouri researchers replaced liquid with frozen ethanol. Ethanol is a type of alcohol that freezes into a protective ice layer. This ice shields delicate biological surfaces during the patterning process. The method allows scientists to work with materials too fragile for older techniques. They tested it on Halobacterium salinarum, a microorganism with a purple protein that captures sunlight for energy, like a natural solar panel.
The researchers place the biological material on a cold surface in a scanning electron microscope. They lower the temperature below -150°C, then add ethanol vapor. The vapor freezes into a thin ice layer over the material. An electron beam, a stream of charged particles, draws patterns in the ice. After warming the surface, untouched ice turns into gas and disappears, leaving the solid pattern behind.
How the process advances science
This ice lithography method creates patterns smaller than 100 nanometers. The process leaves the biological material nearly unchanged, losing less than one nanometer of thickness. This precision opens possibilities for creating new technologies, like solar panels using biological materials.
The discovery combines biology, chemistry, and physics. Researchers used a tool called surface-enhanced Raman scattering to study the patterned material. This tool shows how light interacts with molecules, revealing the material resembles carbon fiber. They also found ketene, a temporary chemical formed during the process. Ketene helps explain how ethanol ice becomes a stable, solid pattern.
Only three labs worldwide use ice lithography, and Missouri’s is the only one in North America. Their use of ethanol ice sets them apart, as water ice can harm delicate materials. This breakthrough could change how scientists handle life’s smallest parts, like molecules and proteins.
