What is a chiral molecule?
A chiral molecule exists in two forms that are mirror images of each other but cannot be lined up exactly the same way. These pairs are called enantiomers.
Enantiomer molecules are often described as being respectively left-hand and right-hand, as they can be compared to your hands: They look the same, but you can’t stack them perfectly on top of each other.
So a molecule is chiral if:
- It has a mirror image
- That mirror image doesn’t fit exactly on top of it
This happens, because the molecule has a “center” with four different things attached. This forces it into a left-hand version and a right-hand version
Why is this important, you may ask. Well, the simple answer is: Your body is picky, and enantiomers can behave differently in biological systems.
Distinction of enantiomers with mirror image pairs of chiral molecules is vital. Even though the two molecules have the same chemical formula and bonding, their three-dimensional arrangements are different.
In practice this means that one can be a beneficial drug, while the other can be detrimental to human health, impacting on drug discovery and screening in biopharmaceutical applications.
Detection
Circular dichroism (CD) spectroscopy measures the difference in how chiral molecules absorb left-handed versus right-handed circularly polarized light in the ultraviolet and visible range.
This difference in absorption reveals whether a molecule is chiral, identifies its handedness, and – through the absorption strength – provides information about its concentration.
CD spectroscopy is therefore widely used for structural analysis and for studying chiral compounds.
However, CD signals are usually very weak, which makes detecting molecules at low concentrations difficult. To improve the detection of enantiomers, light-matter interactions must be enhanced to amplify the polarization-dependent absorption, producing signals strong enough to be reliably measured.
Turning up the interaction
Takayama aims to create a new CD spectroscopy method with nanostructures able to support highly localized light waves and enhance light-matter interaction, boosting its interaction with chiral molecules, improving sensitivity for biopharmaceutical applications.
Supported by the Carlsberg Foundation he will build a spectroscopic setup detecting chiral molecules optically, and allow the characterization and development of metasurfaces for sensing applications.
If successful, the developed technology can help speed up the screening process of medicine and drug development with fewer side effects.
