Biomacromolecular-Assembled Nanoclusters: Key Aspects for Robust Colloidal SERS Sensing.

Area of Science:

• Nanotechnology and Materials Science
• Analytical Chemistry
• Spectroscopy

Background:

• Superstructures of gold nanospheres exhibit enhanced surface-enhanced Raman scattering (SERS) capabilities.
• Achieving reliable and quantitative colloidal SERS probes requires addressing hotspot excitation, analyte adsorption, and stability.

Purpose of the Study:

• To investigate core/satellite gold nanosphere superstructures as a model system for robust colloidal SERS probes.
• To optimize SERS efficiency, analyte adsorption monitoring, and colloidal stability for practical sensing applications.

Main Methods:

• Assembly of core/satellite gold nanosphere superstructures using bovine serum albumin (BSA) as a linker and stabilizer.
• Quantification of SERS activity using 4-mercaptobenzoic acid (MBA) as a model analyte.
• Analysis of SERS efficiency, limit of detection, and colloidal stability under varying conditions.

Main Results:

• BSA coating provides electrosteric stabilization and its spectral signature acts as an internal standard for monitoring analyte adsorption kinetics.
• The superstructures achieved a limit of detection of 10^-7 M for MBA, demonstrating high SERS efficiency.
• Superstructures exhibited superior colloidal stability compared to individual protein-coated or citrate-stabilized gold nanoparticles.

Conclusions:

• Core/satellite gold nanosphere superstructures offer a robust platform for quantitative SERS sensing.
• The study provides practical guidelines for designing stable and efficient colloidal SERS probes by understanding hotspot formation mechanisms.