Image: Capasso Lab/Harvard SEAS

These beetles may look like two different species, but they’re the same individual. The difference lies in how they were photographed, using a new lens that allows scientists to “see” one of the most fundamental properties of biology: chirality.

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Many of the building blocks of life are geometrically chiral, meaning they come in a “left handed” or “right handed” version but not both. The amino acids that make up our proteins, for instance, are all left handed, while the backbone of our DNA is built of right-handed sugars. Being able to distinguish molecules based on chirality is crucial in everything from drug design to origins of life research. But until now, scientists have needed bulky and expensive equipment to do so.

Image: Capasso Lab/Harvard SEAS

Now, engineers at Harvard are making chirality as easy as selfies with an ultra-compact, flat lens that can immediately determine the handedness of an object, by exploiting the direction of rotation (a.k.a. polarization) of light. When the polarization of light “matches” the chirality of a material, the material becomes illuminated.

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For instance, when right-polarized light was shone on the beetle above, its features were indistinct. But strike the same beetle with left-polarized light, and its left-handed chirality is instantly revealed.

In the short term, this lens could help food and drug manufactures easily distinguish between, say, the artificial sweeter Aspartame and its bitter, wrong-handed doppelgänger. Or it could spot the difference between a drug that helps people and one that wreaks havoc on the body.

Thinking more wishfully, future humans might use a version of this chirality lens to study life on other worlds. A tiny geometric shift could mean the difference between a planet that’s compatible our biology and one that isn’t—and that’s ideally something we’d like to know before we send out colonists.

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[Harvard News]