Dynamic Behavior of Surface-Enhanced Raman Spectra for Rhodamine 6G Interacting with Gold Nanorods: Implication for Analyses under Wet versus Dry Conditions

Abstract

We report the dynamic behavior of surface-enhancement Raman scattering (SERS) spectra using rhodamine 6G dye (R6G, 10–8 mol L–1) adsorbed on gold nanorods (AuNRs). SERS spectra displayed a strong time-dependence intensity in wet to dry transition states. FEG-SEM images reveal a stacking of AuNRs organization that can lead to Raman signal improvements due to the formation of a 3D hot spot matrix that acts as a trap for target molecules. AuNRs nanostructured films were efficiently employed to form SERS substrates. The independent random AuNR organization in the SERS spectra exhibits a characteristic profile of intensities due to different dielectric environmental conditions. Despite the variations observed in the spectra array, a pattern was recognized by statistical analysis. Multidimensional analysis ensured the distinction of the study’s requirements applied to the SERS response, exhibiting a silhouette coefficient of 0.92 with the least-squares projection technique. Changes in the SERS spectra profile from wet to dry state conditions of R6G dye solution can be interpreted as the dynamic behavior of R6G molecules correlated to distinct molecular adsorption and (or) surface distribution of the R6G molecules proving different plasmonic resonances. Simulations obtained from BEM calculation in experimental data corroborate that the SERS enhancement is strongly dependent on the nanoparticle coupling in nanoscale and the dielectric environment.

Au@Ag Dendritic Nanoforests for Surface-Enhanced Raman Scattering Sensing

“…De Barros et al [ 42 ] presented the theoretical evaluation of the SERS enhancement factor, , by boundary element method (BEM) numerical calculation. The SERS enhancement factor, related to numerous wavelengths of light, can be evaluated using near-field electromagnetic field intensity; see Equation (1) of [ 42 ]. represents the focusing efficiency of the source light in step (i).…”

“…Results for the SERS enhancement factor [ 42 ], , which are related to various wavelengths of light, can be calculated using the following equation: …”

Silicon Microchannel-Driven Raman Scattering Enhancement to Improve Gold Nanorod Functions as a SERS Substrate toward Single-Molecule Detection

“…Consequently, it creates a tremendous impact on the optoelectronic properties with the most desirable configuration for SERS applications . Herein, the LSPR band of the colloidal AuNR solution is characterized at 715 nm, with the side-by-side AuNR arrangement favoring a blue shift in the LSPR band using a 633 nm excitation wavelength, which was already reported by our group . Therefore, we are working on the resonance particle condition that leads to a significant intensified field.…”

“…Several strategies have been developed for a better performance of SERS substrates, , such as the aggregation of nanoparticles induced by organic solvents like alcohols, or using cucurbit­[urils] molecules to form a large number of hot spots. Alternative SERS strategies have been reported for the analyte drying dynamics on a SERS substrate , and in situ analysis performed by microfluidic-type continuous flow methodologies . de Barros et al used a SERS approach based on different dielectric environment analyses to explain the dependence of SERS signals in a relationship to the dynamic behavior of rhodamine 6G (R6G) when adsorbed on a gold nanorod (AuNR) surface.…”

“…Alternative SERS strategies have been reported for the analyte drying dynamics on a SERS substrate , and in situ analysis performed by microfluidic-type continuous flow methodologies . de Barros et al used a SERS approach based on different dielectric environment analyses to explain the dependence of SERS signals in a relationship to the dynamic behavior of rhodamine 6G (R6G) when adsorbed on a gold nanorod (AuNR) surface.…”