Inferring the Interfacial Reactivity of Gold Nanoparticles by Surface Plasmon Resonance Measurements

Area of Science:

• Nanotechnology
• Surface Chemistry
• Analytical Chemistry

Background:

• Gold nanoparticles (GNPs) functionalization is essential for applications but optimizing it is complex.
• Current methods for assessing GNP grafting and stability are time-consuming and resource-intensive.
• Developing efficient methods to predict GNP surface reactivity is critical.

Purpose of the Study:

• To investigate ligand reactivity on gold surfaces using Surface Plasmon Resonance (SPR) as a model for GNP suspensions.
• To compare the grafting efficiency and stability of two thiolated ligands (thioglycolic acid and 6-mercaptohexanoic acid) under various conditions.
• To validate SPR as a predictive tool for GNP functionalization.

Main Methods:

• Utilized Surface Plasmon Resonance (SPR) to monitor ligand grafting on a gold surface.
• Employed optical absorption spectroscopy to monitor ligand grafting on gold nanoparticles (GNPs).
• Compared grafting efficiency and suspension stability for thioglycolic acid (TA) and 6-mercaptohexanoic acid (MHA) under different conditions.

Main Results:

• SPR measurements on gold surfaces accurately predicted ligand reactivity observed in GNP suspensions.
• Both SPR and optical absorption indicated that low concentrations of thiols in aqueous solutions yield optimal grafting and stability.
• The study identified optimal conditions for functionalizing GNPs with TA and MHA.

Conclusions:

• Surface Plasmon Resonance (SPR) is a suitable and efficient method for predicting the outcome of gold nanoparticle (GNP) functionalization.
• Optimizing GNP functionalization involves introducing thiol molecules in dilute aqueous solutions.
• This approach reduces material waste and accelerates the development of functionalized GNPs for various applications.