New research could improve detection of chiral molecules in pharmaceuticals and biotechnology

Ohio University physicist Alexander Govorov and colleagues have developed a groundbreaking method for detecting molecular chirality with unprecedented sensitivity. The study, published in Science Advances, introduces spiral gold plasmonic metastructures that amplify both electric and superchiral optical near fields. These structures enhance nonlinear optical processes, particularly circularly polarized second-harmonic generation, which creates a highly sensitive optical signal when chiral molecules interact with their surfaces.

The key advantage of this nonlinear chiroptical sensing approach lies in its dramatic amplification of weak molecular chiroptical signals. Traditional linear methods, such as circular dichroism and optical rotatory dispersion spectroscopy, scale approximately as P, where P is the plasmonic electromagnetic enhancement factor. In contrast, the new nonlinear approach scales approximately as P², allowing for the detection of chirality at extremely low concentrations.

This enhanced sensitivity has significant implications for various fields. In pharmaceuticals, it enables reliable and highly sensitive on-chip detection of chiral molecules and drugs, facilitating rapid and efficient quality control and development processes. In biomedical analysis, the technology allows for faster and more accurate detection of enantiomers in biological samples, potentially leading to more precise diagnoses and treatments.

Additionally, the system's ability to distinguish between different enantiomers even in racemic mixtures without chromatographic separation could revolutionize fields such as agriculture, environmental monitoring, and forensic studies, where identifying molecular handedness is crucial.