Open-access Surface-Enhanced Raman Scattering-Based Adsorption Isotherm of 4-Mercaptobenzoic Acid in Chitosan-Protected Gold Nanoparticles

Abstract

4-Mercaptobenzoic acid (4-MBA) adsorption behavior was studied through an adsorption isotherm with surface-enhanced Raman scattering as the spectroscopic probe molecule, using chitosan-protected gold nanoparticles (AuNP). As the surface coverage was lower, 4-MBA molecules were reoriented, which led to the carboxylate group interaction with AuNP, besides the thiolate interaction, based on experimental and density-functional theory-based results. The adsorption process was fitted considering Langmuir isotherms, and a Gibbs energy of adsorption of -25 kJ mol-1 was obtained.

Keywords:
4-mercaptobenzoic acid; gold nanoparticle; adsorption isotherm; surface-enhanced Raman spectroscopy; chitosan


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