Characterization of silane-modified immobilized gold colloids as a substrate for surface-enhanced Raman spectroscopy

Area of Science:

• Nanotechnology
• Surface Science
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful technique for molecular analysis.
• Developing stable and reproducible SERS substrates is crucial for reliable measurements.
• Hydrophobic surfaces present unique challenges for adsorption studies.

Purpose of the Study:

• To characterize immobilized gold colloid particles as SERS substrates for hydrophobic surfaces.
• To investigate the effect of gold aggregation on SERS enhancement.
• To evaluate the protective and adsorptive properties of a C-18 alkylsilane coating.

Main Methods:

• Preparation and characterization of gold colloid on glass substrates.
• Atomic force microscopy (AFM) for surface morphology.
• Optical extinction spectroscopy for plasmon resonance.
• SERS measurements to assess enhancement and adsorption.
• Self-assembly of octadecyltrimethoxysilane (OTS) for surface modification.

Main Results:

• SERS enhancement increased with gold particle aggregation until plasmon resonance shifted.
• Gold colloid substrates demonstrated stability and reproducible SERS enhancement.
• C-18 silane coating successfully inhibited chemisorption of a disulfide reagent.
• Physisorption at the C-18/solution interface was minimally affected by the silane layer.
• Overcoated gold substrates showed reproducible and stable SERS enhancement.

Conclusions:

• Immobilized gold colloid particles coated with C-18 silane are effective SERS substrates for hydrophobic surfaces.
• The C-18 layer selectively blocks gold interactions while preserving physisorption.
• These substrates offer stability, reproducibility, and suitability for studying adsorption phenomena.