Surface-enhanced Raman scattering for ultrasensitive chemical analysis of 1 and 2-naphthalenethiols

Abstract

The results of the search for the optimal experimental conditions for ultrasentitive chemical analysis of 1-naphthalenethiol (1-NAT) and 2-naphthalenethiol (2-NAT) using surface-enhanced Raman scattering (SERS) are discussed. The report begins with a review of the vibrational spectra, including infrared and Raman spectra of the target molecules, and the interpretation of the observed frequencies aided by local density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) level of theory. Several metal nanostructures were tested for SERS activity, including island films and colloids of silver, gold and copper. Correspondingly, the most effective laser line for excitation in the visible and near infrared region was sought. The achieved detection limit for 1-naphthalenethiol, and for 2-naphthalenethiol, on silver nanostructures is in the zeptomole regime.

Surface-enhanced hyper Raman hyperspectral imaging and probing in animal cells

“…All bands in the spectrum of the pMBA SEHRS label in the culture medium are in good agreement with the SEHRS spectrum of pMBA obtained on different silver nanostructures and discussed in detail recently. 18 The spectrum of the 2-NAT SEHRS label in culture medium displays bands that are also known from the SERS spectra of 2-NAT 34,35 and of the same 2-NAT SERS labels composed of silver nanoparticles 11 though with different relative intensities. The SEHRS spectra obtained from the SEHRS probes at the incubation concentration in the culture medium show very weak signals, due to the relatively small number of reporter molecules in this experiment.…”

“…Compared to the signals obtained from the SEHRS labels in the culture medium, the SEHRS signatures are more enhanced when obtained inside the cells, due to the high concentrations of silver nanoparticles that are yielded inside the focal volume in regions with many endosomal structures 9 and the beneficial plasmonic properties that are generated during the formation of different vesicular structures. 10 The full coverage of the silver nanostructures with the reporter molecules and their interaction via the thiol group 29,34 prevents an interaction of other molecules so that no intrinsic signals from the culture medium (Fig. 1b) or from the cells (Fig.…”

Probing Ionic Diffusion Dynamics through the Modulation of Polymer Shell Using Surface-Enhanced Raman Spectroscopy

“…Raman active ligands such as 2-napthalenthiol (2-NT) can produce characteristics SERS spectrum when attached onto metallic surfaces [17]. In this study, this ligand was chosen to tune the interfacial energy between Au-polymer [18], forming core-shell nanoparticles of AuNP@ PSPAA [19].…”

“…In this study, this ligand was chosen to tune the interfacial energy between Au-polymer [18], forming core-shell nanoparticles of AuNP@ PSPAA [19]. In order to probe the effect of ionic diffusion, small amount of cyanide was added and allowed to be diffused across PS, under varying experimental parameters, to etch the AuNPs over 90 h. We monitored the Raman shift of 1067 cm -1 corresponding to the symmetric C-H bending vibrational mode of 2NT, which has a strong SERS intensity [17], and envisioned that as ionic diffusion of cyanide proceeds, the intensity of this band will decrease. As the AuNPs are being etched by the cyanide ions, soluble ions of Au(CN)2-will be formed.…”

“…While the resulting AuNP@Cholesterol@PSPAA allows us to probe the effects of cholesterol in relation to its ionic permeability with PS, the lack of strong SERS signal makes it difficult for us to monitor the rate of cyanide diffusion. Therefore, we adopted a dual ligand approach, by using both 2NT and TC, where we are able to make use of the SERS signals of the former ligand [17] to probe the effects of ionic diffusion across PS. Additionally, we also chose a shorter PSPAA chain, consisting of 17 units of PS and 83 PAA, to better understand the cholesterol-PS interaction.…”