Structural characterisation and dynamic modelling of pegylated graphene oxide with Ag and Cu nanocluster

Abstract

Graphene (G) and graphene oxide (GO) are increasingly employed in energy, materials, and healthcare sectors. Silver (Ag) and copper (Cu) nanomaterials, including their nanoclusters, are crucial for advanced antimicrobial therapies and improving the performance of materials in energy and biomedical applications. However, achieving uniform dispersion and stability in both hydrophobic and hydrophilic environments remain a challenge. This study addresses these challenges by synthesizing and characterizing PEGylated GO30 functionalised with Ag and Cu nanoclusters through amide bond formation. Using TEM, SEM, UV–Visible spectroscopy, FTIR, Raman spectroscopy, TGA, and molecular dynamics (MD) simulations, we identified optimal strategies and mechanism for stabilising these nanoclusters as well as the nanostructures. The oxidation and subsequent PEGylation of graphene significantly enhance the interaction energy of Ag nanoclusters by 239.47 kcal/mol and Cu nanoclusters by 259.98 kcal/mol. This functionalisation (GO-PEG-NH2) also substantially reduces nanocluster mobility on the graphene-based surface, with mean squared displacement (MSD) values of 20–30 Å2 at 500 ps, compared to 150–175 Å2 for non-functionalised graphene clusters. SEM and TEM analyses show that PEGylation promotes nanoparticle dispersion and reduces aggregation on GO30 sheets, achieving a more consistent size distribution of 10–20 nm. U-Visible spectroscopy reveals that PEGylated Ag nanoparticles exhibit a stable plasmonic response between 400–450 nm, while the broadening of decomposition peaks indicates improved thermal stability and uniform heat distribution. Overall, PEGylation markedly enhances the stability, dispersion, and functionality of metal nanoclusters on graphene-based materials, underscoring their potential for drug delivery, antimicrobial technologies, and energy storage, while laying a strong foundation for future research in functional nanomaterials.