In situ nucleation and growth of silver nanoparticles in membrane materials: a controllable roughened SERS substrate with high reproducibility

Abstract

A controllable roughened silver surface with high surface-enhanced Raman scattering (SERS) activity and high reproducibility has been developed in this study. This silver surface was prepared by silver nucleation in polyelectrolyte multilayers (PEMs) and silver-enlarged growth. First, the small Ag nuclei were synthesized by NaBH 4 in situ reduction of Ag ions on a surface of PEMs. Then the small Ag nuclei formed were effectively enlarged by using a mixture of commercially available reagents named Li Silver. The optical properties and morphologies of the silver substrates have been investigated by ultraviolet-visible (UV-vis) spectroscopy and atomic force microscopy (AFM). The UV-vis and AFM results revealed that the small Ag nuclei separately appeared on the PEMs after NaBH 4 in situ reduction. The size of the enlarged Ag nanoparticles can be easily controlled with the immersing cycle in Li Silver. 4-Mercaptopyridine (4-MPY) and Rhodamine 6G (R6G) have been used as Raman probes to evaluate the properties of the new SERS substrates. It has been found that the enhancement factor of R6G reached ∼10 9 after treatment in Li Silver. Reproducibility has been investigated using the SERS signal intensity at 1094 cm −1 of 4-MPY. Signals collected over multiple spots within the same substrate resulted in a relative standard deviation (RSD) of 6.38%, while an RSD of 10.33% was measured in signals collected from different substrates.

Glass‐embedded silver nanoparticle patterns by masked ion‐exchange process for surface‐enhanced Raman scattering

“…As can be seen, R6G can be detected down to 1 nM concentration. Raman signal of R6G has been demonstrated at this concentration level, [15,16,27] and even lower concentrations have been detected. [28] However, the sensitivity of a biosensor can also be influenced by the incubation conditions and the measurement parameters.…”

“…To obtain the enhancement factor, we use in our calculation the formula G = (I surf /I flu ) × (N Raman /N surf ) × 10 9 derived from Ref. [27], as their excitation wavelength (514.5 nm) is close to ours. In this formula, N Raman and N surf denote the number of R6G molecules which contribute to the unenhanced Raman and SERS intensities respectively, I surf denotes the corresponding SERS intensity, and I flu is the fluorescence intensity under the same experimental conditions with the unenhanced Raman scattering.…”

Advance in Tribology Study of Polyelectrolyte Multilayers

“…Then, the postbinding chemistries include reduction, hydroxide, sulfidation, and growth nanoparticles from the cationic precursors [49,50,68]. For instance, the schematic diagram of the preparation process of in situ CuS/ZnS nanoparticles hybrid PEMs is shown in Figure 5.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part IV

“…[5] The nanostars were fabricated from anistropic metallic nanoparticles, and the shape of these particles provided noticeably stronger SERS response compared to the corresponding spherical nanoparticles of the same size. Membrane material providing a controllable roughened surface for the in situ nucleation and growth of polyelectrolyte silver multilayers that yielded high SERS activity and high reproducibility was reported by Zhou et al [6] SERS spectra of 2-amino-5-nitropyridine (ANP) on colloidal silver triangular nanoplates were measured by Sant'Ana et al using samples with different mean sizes and surface plasmon frequencies. [7] Here, detailed characterization of morphology and concentration allowed a quantitative correlation between the SERS profiles and the mean size of the nanoplates.…”