Thermodynamics and Mechanisms of the Interactions between Ultrasmall Fluorescent Gold Nanoclusters and Human Serum Albumin, γ-Globulins, and Transferrin: A Spectroscopic Approach

Abstract

Noble metal nanoclusters (NCs) show great promise as nanoprobes for bioanalysis and cellular imaging in biological applications due to ultrasmall size, good photophysical properties, and excellent biocompatibility. In order to achieve a comprehensive understanding of possible biological implications, a series of spectroscopic measurements were conducted under different temperatures to investigate the interactions of Au NCs (∼1.7 nm) with three model plasmatic proteins (human serum albumin (HSA), γ-globulins, and transferrin). It was found that the fluorescence quenching of HSA and γ-globulins triggered by Au NCs was due to dynamic quenching mechanism, while the fluorescence quenching of transferrin by Au NCs was a result of the formation of a Au NC-transferrin complex. The apparent association constants of the Au NCs bound to HSA, γ-globulins, and transferrin demonstrated no obvious difference. Thermodynamic studies demonstrated that the interaction between Au NCs and HSA (or γ-globulins) was driven by hydrophobic forces, while the electrostatic interactions played predominant roles in the adsorption process for transferrin. Furthermore, it was proven that Au NCs had no obvious interference in the secondary structures of these three kinds of proteins. In turn, these three proteins had a minor effect on the fluorescence intensity of Au NCs, which made fluorescent Au NCs promising in biological applications owing to their chemical and photophysical stability. In addition, by comparing the interactions of small molecules, Au NCs, and large nanomaterials with serum albumin, it was found that the binding constants were gradually increased with the increase of particle size. This work has elucidated the interaction mechanisms between nanoclusters and proteins, and shed light on a new interaction mode different from the protein corona on the surface of nanoparticles, which will highly contribute to the better design and applications of fluorescent nanoclusters.

Human Serum Albumin in the Presence of AGuIX Nanoagents: Structure Stabilisation without Direct Interaction

“…This would result in a decrease in the fluorescence quenching (Ksv and kq) and an increase in the fluorescence yield [73], which is different from our results. This result is in agreement with the dynamic quenching of HSA by AuNPs reported by Foo et al and Yin et al [74,75].…”

Differences between the binding modes of enantiomers S/R-nicotine to acetylcholinesterase

“…When the drug and protein combine, the chromophore absorption peak position or peak width of the biomacromolecular protein may be changed, which can be used to determine the inuence of the binding on the protein conformation. 46 As shown in Fig. 11, the absorption spectrum of AChE at around 205 nm corresponds to the peptide bond absorption of the AChE.…”

Investigating the Interaction of Nanodiamonds with Human Serum Albumin and Induced Cytotoxicity

“…Several previous reports have investigated the interactions of various nanomaterials with HSA and the induced structure change and stability of proteins [15][16][17]. Yin et al investigated the interactions of Au nanoclusters with three model proteins (HSA, c-globulins, and transferrin), and the hydrophobic force between them was proved [18]. Zhang et al used HSA to modify a gadolinium-fullerene derivative for obtaining a macromolecular magnetic resonance imaging contrast agent [19].…”