Exploring the nanoscale: AFM-IR visualization of cysteine adsorption on gold nanoparticles

Dominika Święch; Kamila Kollbek; Piotr Jabłoński; Marta Gajewska; Gaetano Palumbo; Magdalena Oćwieja; Natalia Piergies

doi:10.1016/j.saa.2024.124433

Exploring the nanoscale: AFM-IR visualization of cysteine adsorption on gold nanoparticles

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Oct 5:318:124433. doi: 10.1016/j.saa.2024.124433. Epub 2024 May 9.

Authors

Dominika Święch¹, Kamila Kollbek², Piotr Jabłoński², Marta Gajewska², Gaetano Palumbo³, Magdalena Oćwieja⁴, Natalia Piergies⁵

Affiliations

¹ AGH University of Krakow, Faculty of Foundry Engineering, av. Mickiewicza 30, PL-30059 Krakow, Poland. Electronic address: dswiech@agh.edu.pl.
² AGH University of Krakow, Academic Centre for Materials and Nanotechnology, av. Mickiewicza 30, PL-30059 Krakow, Poland.
³ AGH University of Krakow, Faculty of Foundry Engineering, av. Mickiewicza 30, PL-30059 Krakow, Poland.
⁴ Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
⁵ Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland.

PMID: 38761470
DOI: 10.1016/j.saa.2024.124433

Abstract

This study focuses on the adsorption process of L-cysteine (Cys), a sulfur-containing amino acid, onto monolayers of gold nanoparticles (AuNPs) prepared through distinct protocols on mica substrates. Two types of AuNPs were prepared using two different methods: the first employed a physical approach, which combined the Inert Gas Condensation (IGC) technique with the magnetron sputtering method, while the second utilized a chemical method involving the reduction of tetrachloroauric acid with trisodium citrate (TC). The characterization of AuNPs was performed using transmission electron microscopy (TEM) and atomic force microscopy (AFM), of up to 5 ± 1.3 nm for bare AuNPs obtained through vacuum techniques, and up to 12 ± 5 nm for negatively charged, citrate-stabilized TCAuNPs(-). The application of spectroscopic techniques based on the surface-enhanced effects allows for describing the adsorption process in both micro- and nanoscale systems: Cys/bare AuNPs and Cys/ TCAuNPs(-). The commonly used surface-enhanced Raman spectroscopy (SERS) technique provided insights into adsorption behaviours at the microscale level. In the case of TCAuNPs(-), an interaction involving the lone electron pair of sulfur (S) atom and metal surface, while on the bare AuNPs, S is adsorbed on the surface, but the cleavage of the SH group is not discernible. Nanoscale analysis was complemented using AFM combined with the surface-enhanced infrared absorption spectroscopy (AFM-SEIRA) technique. AFM-SEIRA map indicated the formation of hot spot which were predominantly located between aggregated TCAuNPs(-) and on specific NPs surfaces (area between NPs and gold-coated tip). Results from the SERS and AFM-SEIRA techniques were in good agreement, underscoring the comprehensive understanding achieved through the chosen experimental approach regarding the Cys interactions with layers of AuNPs.

Keywords: L-cysteine (Cys); atomic force microscopy in combination with surface-enhanced infrared absorption spectroscopy (AFM-SEIRA); gold nanoparticles (AuNPs); surface–enhanced Raman spectroscopy (SERS).