Surface-enhanced Raman Scattering and Localized Surface Plasmon Resonance Detection of Aldehydes Using 4-ATP Functionalized Ag Nanorods

Abstract

AbstractFormaldehyde, acetaldehyde, and benzaldehyde are well-known carcinogens affecting human health adversely. Thus, there is a need for efficient detection of these aldehydes. This work uses 4-aminothiophenol (4-ATP) functionalized silver nanorods (Ag NRs) to detect these three aldehydes. The detection mode includes localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS). The LSPR band of 4-ATP functionalized Ag NRs shows a linear decrease in absorbance with the increase in formaldehyde and acetaldehyde concentrations. A sensitivity of 0.96 and 0.79 ΔA/mM for formaldehyde and acetaldehyde were obtained. In the case of benzaldehyde, a nearly exponential decrease in absorbance with the increase in concentrations was observed. Above 98.4 μM concentration, the absorbance diminishes completely. The LoD for formaldehyde and acetaldehyde detection using LSPR is 33.8 and 24.6 μM, respectively. The SERS studies reveal that the 4-ATP binds to Ag NRs through both –SH and –NH2 groups and facilitates the inter-particle charge transfer process. The appearance of b2 modes of vibration for 4-ATP evidences this charge transfer process. In the presence of aldehydes, the change in the band shape, relative intensities, and band position were observed primarily in b2 modes of vibration, evidencing the modulation in the charge transfer process. These remarkable changes were seen in μM concentration of aldehydes. Therefore, detection of these aldehydes with 4-ATP functionalized Ag NRs using SERS is possible in concentrations as low as ~ 1 μM.