Nanocubes are structures unfamiliar to many outside of the nanobiotechnology discipline. By name, these structures almost sound like a popular children’s toy. Illustrations of nanocubes even appear somewhat illusory, with their vivid primary colors and playful shapes. However, it was during the process of building one of these tiny cubes that revealed brand new information about how molecules bind together in natural environments.
Initially, researchers at the University of Tokyo’s Department of Basic Science set out to build several tiny, self-assembling structures using the power of the interactions between the molecules that compose them. These researchers were particularly interested in how the hydrophobic effect and its associated forces caused two molecules to behave in relation to one another. Generally, two molecules that are surrounded by water tend to move toward one another, due to the chemical force of each to repel water.
These other forces, known as Van Der Waals forces, are markedly present in hydrophobic reactions via the dispersion force. It is thought that dispersion forces are the primary force that keeps snowflakes arranged in their familiar, hexagonal patterns. Since the dispersion force is among one of the weakest forces in nature but is present in so many essential chemical interactions, studying it is both very important and very difficult.
Nanocubes and Dispersion Forces
Previously, studying weak dispersion forces under natural conditions was next to impossible. However, researchers were able to determine that the study of self-assembling nanocubes—molecules arranged in a structure that takes on a cube shape because of the nature of the dispersion forces between each molecule—could be amplified. Scientists carefully selected the molecules involved, choosing those with polarizable atoms that would be responsive to an electric field.
With so many reactive atoms, the collective dispersion forces were great enough to be measurable. As researchers added more and less polarizable atoms, they found they could measure changes in dispersion forces through a process called isothermal titration calorimetry. Their observations revealed that polarizable atoms increased dispersion forces and stabilized the nanocube’s structure, paving the way for continued research surrounding such atoms.
Scientists hope to continue studies of polarizable atoms and dispersion forces to create increasingly complex shapes. This could lead to the ability to design structured molecules that feature more binding surfaces on the exterior and allow them to remain stable and bind to more molecules when interacting with other molecules. Many of the discoveries involved in this groundbreaking research could potentially be used in the drug design and pharmaceutical industries.
Researchers continue to make new discoveries about how molecules bind together in natural environments. Drug researchers once believed that larger, or “heavier” molecules and atoms exert a stronger dispersion force upon other molecules and atoms.
However, further research seems to confirm that exchanging a “heavy” molecule for a lighter one has little effect on dispersion forces if the overall free energy exhibited remains the same. One thing is for sure, the future is bright for nanocubes and other nanostructures and this could mean advances in the design of medications and other molecules essential to human life.