금 나노 입자를 활용한 표면증강라만산란 : 기초와 응용

Abstract

Discovered from pyridine adsorbed on the roughened silver, surface-enhanced Raman scattering (SERS) has been a useful technique to overcome the main disadvantage of Raman spectroscopy that the signals are weak. SERS has little limitations in sample and enable to analyze very small amounts with high sensitivity or solution sample. Also, this technique is a non-destructive method and advantageous for biological sample analysis. Numerous studies have studied widely to understand this phenomenon, extending Raman spectroscopy and applying for various fields such as plasmonic and chemical sensing in nanoscale.

Herein, basic, mechanism and application research on SERS with gold nanoparticles were conducted. On basic study, we optimized the SERS effect and figured out several factors with gold nanourchins (AuNUs) that had sharp tips and the rhodamine 6G (R6G) as the probe molecules, controlling the parameters individually that were binding time, metal-to-molecule ratio, centrifugation, and stirring that decided the SERS enhancement. Second, the mechanism of SERS, especially chemical enhancement, has been studied with the assumption that electron withdrawing group (EWG) promoted a charge-transfer. Gold nanorods (AuNRs) and thiophenol derivatives substituted with electrophilicity on para-position were used, proving the assumption on EWG but more complicated approaches such as intermolecular interaction and solvent effect were needed on electron donating group (EDG) study. Finally, cucurbit[n]urils (CB[n]), one of useful supramolecular materials, were used to overcome the limitation of SERS that the adsorbed molecules had to interact with metal surface. By encapsulation of the probe molecules in cucurbit[7]urils (CB[7]) with host-guest interaction and adsorbing CB[7] on surface of AuNRs, the enhanced signal showed a long-term stability for 20 days. These results are helpful to understand deeply SERS, providing information about its principle, mechanism, the factors affecting its enhancement and suggest the potential to utilize SERS on various fields by introducing supramolecular CB[n].