Chiral Gold Nanofibers as Substrates Toward SERS-Based Chiral and Flexible Sensing

Chiral plasmonic nanostructures offer unique opportunities for combining surface-enhanced Raman scattering (SERS) with enantioselective molecular recognition. However, their integration into practical sensing platforms remains challenging. Here, we demonstrate high-aspect-ratio chiral gold nanofibers as versatile substrates for sensitive, chiral, and flexible SERS sensing. Using trans-1,2-bis(4-pyridyl)ethene as a model analyte, the chiral gold nanofibers enable molecular detection down to 1 nM and exhibit higher SERS efficiency (between 2-3× higher) than benchmark nanomaterials such as chiral and achiral gold nanorods. Beyond molecular detection, the chiral gold nanofibers provided indications of composition-dependent discrimination between D- and L-cysteine in mixtures with different enantiomeric compositions above analyte concentrations of, at least, 10 mM. Finally, the chiral gold nanofibers retain their SERS activity after integration into low-cost, flexible paper scaffolds, enabling spatial mapping and recovery of characteristic molecular fingerprints across the heterogeneous surface. These results establish chiral gold nanofibers as potential multifunctional plasmonic building blocks that combine molecular sensitivity, enantioselective recognition, and compatibility with flexible surfaces, providing a route toward adaptable platforms for label-free chiral sensing.