Strategy for improved analysis of peptides by surface‐enhanced Raman spectroscopy (SERS) involving positively charged nanoparticles

Abstract

A strategy for improved surface-enhanced Raman spectroscopy (SERS) measurements that extends the variety of analytes accessible to SERS analysis is developed. The strategy involves inducing aggregation by mixing positively charged nanoparticles which form SERS-active clusters when mixed with negatively charged silver nanoparticles fabricated using the Lee-Meisel process. To make positively charged nanoparticles, silver nanoparticles using the traditional Lee-Meisel process are fabricated and coated with a thin layer of silica and the silica modified with silane chemistry. Analytes with a significant amount of negative charge exhibit strong Raman bands when the strategy using these fabricated, positively charged nanoparticles for inducing cluster formation is used, enabling their detection and analysis. We envision the use of positively charged nanoparticles in cluster formation for expanding the range of analytes that can be detected using SERS and hence the range of applications SERS can play a role in.

Simple preparation of positively charged silver nanoparticles for detection of anions by surface-enhanced Raman spectroscopy

“…19 This model could explain how gradual addition of thiocholine aggregates a negatively charged colloid, as the positive head group would be attracted to the negative surface and reduce the charge on the nanoparticle, causing the colloid to aggregate even without direct reaction between the thiol and the Ag surface. 19 This model could explain how gradual addition of thiocholine aggregates a negatively charged colloid, as the positive head group would be attracted to the negative surface and reduce the charge on the nanoparticle, causing the colloid to aggregate even without direct reaction between the thiol and the Ag surface.…”

“…9 Detection of negatively charged analytes by co-adsorption onto conventional Ag and Au colloids which have a negative zeta potential will clearly be difficult because of the electrostatic repulsion between analyte and surface ions. 19 However, this method requires reaction with silane compounds, which is inefficient in aqueous solution, and the silica shell can diminish the SERS activity of the nanoparticles. to prepare colloids with surface ions that bind more weakly to the particles than the target molecules, so that when the target molecules are added they can displace the existing layer and be detected.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part III

“…Mitchell et al [21] have performed an experimental and statistical analysis for peptide detection using SERS. Ngola et al [22] developed a strategy for improved analysis of peptides by SERS involving positively charged nanoparticles. Wang et al [23] studied the adsorption of 4,4 -thiobisbenzenethiol on silver surfaces applying SERS while Shin [24] investigated the substrate-dependent SERS of 4-aminobenzenethiol adsorbed on Au surfaces.…”

SERS imaging for label-free detection of the phospholipids distribution in hybrid lipid membrane

“…The applications based on SERS have been demonstrated such as the detection of DNA/RNA, vesicles, proteins, pathogens, and so on [13][14][15][16][17][18]. Besides the recognition with labeled SERS probe, biomolecules can also be distinguished with the inherent molecular specificity of SERS spectra.…”