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| The circular dichroism spectra for short spirals (red) and long spirals (blue). For longer spirals there is a red shift in the mode in the visible regime but not for the mode in the UV. Courtesy Nanotechnology. |
Topics: Biology, Chemistry, Materials Science, Nanotechnology
The chirality of molecular structures can significantly affect a substance’s effect on biological systems, but the low signal means distinguishing chiral signals can be challenging. Fledgling studies in chiral plasmonics hope to exploit the resulting enhancements in chiral detection, just as molecular sensing has benefited from techniques like surface-enhanced Raman scattering. Now researchers have extended the understanding of chiral plasmonics by identifying how structural parameters affect the chiral plasmon signals from silver nanospirals.
"This is like where we were in the 1990s with plasmons," says Zhifeng Huang, associate professor in the Physics Department at Hong Kong Baptist University (HKBU), who led this latest research. "People have been wondering whether it is possible to use chiral plasmons to amplify the signal of chiral molecules, but first we need to understand chiral plasmons." The stakes are high for enhancing chiral signal detection and differentiation, since it has an impact on pharmaceuticals, agriculture, food quality monitoring and control, disease diagnosis and treatment, and environmental protection and sustainable development.
Chirality refers to a property of structures that exist in two versions - "enantiomers" - that are mirror images of each other but cannot be superimposed. Examples of chiral molecules include penicillamine, where the right-handed version is effective for rheumatoid arthritis therapy, whereas the left-handed version is toxic, or aspartame, where the left-handed version tastes sweet and has been patented in the food industry, whereas the right-handed version is tasteless.
Nanotechweb: Helical structures affect chiral plasmons, Anna Demming
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