Bisignate Surface-Enhanced Raman Optical Activity with Analyte-Capped Colloids.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40053825.
- Also identified by DOI 10.1021/acsnano.4c19027 and PMC identifier 11924305.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Spectroscopic detection of chiral compounds is often hampered by a low sensitivity. For Raman optical activity (ROA), the signal can be dramatically increased in surface-enhanced experiments. So far, however, reproducible surface-enhanced ROA (SEROA) spectra were obtained for a reporter molecule only via induced chirality, and the intensities were just proportional to the Raman scattering. In the present study, we show that the signal can be substantially increased if colloidal silver nanoparticles are prepared already in the presence of a chiral analyte. In this case, both the analyte's and reporter's bands are visible. In addition, some experiments provided bisignate SEROA patterns, thus significantly enhancing information about the molecular structure provided by this spectroscopic method. Increased electronic circular dichroism (ECD) of the capped aggregated colloids suggests that ECD and polarized Raman scattering (ECD-Raman) contribute to the monosignate SEROA intensities, while well-dispersed nonaggregating colloids are important for observation of true (bisignate) molecular vibrational SEROA.