Non-thiolated intermolecular and interfacial interactions near gold nanostars and their effect on SERS

Vibrational spectroscopy utilizes vibrational and rotational motion to detect molecules and discern information about chemical bonds. One type of vibrational spectroscopy, Raman scattering, relies on the presence, location, and shape of spectral features to identify molecules and study individual chemical bonds. Surface-enhanced Raman scattering (SERS) is an analytical technique utilizing chemical and electromagnetic enhancements, of Raman scattering, generated near a nanoparticle surface to detect molecular vibrations with high sensitivity. SERS enables molecular detection of concentrations approaching pico- and femtomolar by enhancing Raman intensities from 1 to 13 orders of magnitude. Though SERS has significant advantages, the challenges associated with this technique are equally large in certain scenarios because the nature and design of nanoparticles limits the number and types of molecules detectable through SERS. This thesis explores and addresses a few of the current challenges associated with SERS by further expanding the technical applications through discerning new methods of detection for two different analytes aspirin and Δ9 -tetrahydrocannabinol in solution. The subsequent sections of this study cover the recent advances in SERS before discussing co-solvent effects on non-thiolated molecular detection and the application to saliva samples involving drug-induced impairment.