Probing the Interaction of Bovine Serum Albumin with Copper Nanoclusters: Realization of Binding Pathway Different from Protein Corona

Abstract

With an aim to understand the interaction mechanism of bovine serum albumin (BSA) with copper nanoclusters (CuNCs), three different types CuNCs having chemically different surface ligands, namely, tannic acid (TA), chitosan, and cysteine (Cys), have been fabricated, and investigations are carried out in the absence and presence of protein (BSA) at ensemble-averaged and single-molecule levels. The CuNCs, capped with different surface ligands, are consciously chosen so that the role of surface ligands in the overall protein− NCs interactions is clearly understood, but, more importantly, to find whether these CuNCs can interact with protein in a new pathway without forming the "protein corona", which otherwise has been observed in relatively larger nanoparticles when they are exposed to biological fluids. Analysis of the data obtained from fluorescence, ζ-potential, and ITC measurements has clearly indicated that the BSA protein in the presence of CuNCs does not attain the binding stoichiometry (BSA/CuNCs > 1) that is required for the formation of "protein corona". This conclusion is further substantiated by the outcome of the fluorescence correlation spectroscopy (FCS) study. Further analysis of data and thermodynamic calculations have revealed that the surface ligands of the CuNCs play an important role in the protein−NCs binding events, and they can alter the mode and thermodynamics of the process. Specifically, the data have demonstrated that the binding of BSA with TA-CuNCs and Chitosan-CuNCs follows two types of binding modes; however, the same with Cys-CuNCs goes through only one type of binding mode. Circular dichroism (CD) measurements have indicated that the basic structure of BSA remains almost unaltered in the presence of CuNCs. The outcome of the present study is expected to encourage and enable better application of NCs in biological applications.

Antimicrobial Nano-Agents: The Copper Age

“…The surface ligands of NPs and the interplay with environmental protein (protein corona) can influence the uptake in cells and the interactions with organs, giving a relevant effect in the metabolic pathways, persistence, and toxicity. − Regarding CuNPs and protein corona formation, very few works can be found. Recently, Akhuli et al . investigated the interactions between bovine serum albumin and copper nanoclusters modified with tannic acid, chitosan, or cysteine, reporting that CuNPs interact with BSA without modifying its structure.…”

“…135−137 Regarding CuNPs and protein corona formation, very few works can be found. Recently, Akhuli et al 138 investigated the interactions between bovine serum albumin and copper nanoclusters modified with tannic acid, chitosan, or cysteine, reporting that CuNPs interact with BSA without modifying its structure. Investigations on bio/nano interactions and protein corona formation are of particular interest in order to shed light on ADME and the cellular uptake.…”

Lysozyme protected Cu Nano-Cluster: A Photo Switch for the Selective Sensing of Iron (Fe2+)

“…In our case we could see a very interesting sharp transition at ~10 nM which has not been seen earlier. 45,63,80 The initial high slope indicating the existence of static quenching as the kinetics can not be explained with diffusion controlled quenching only. 79 Involvment of static quenching is further confirmed by lifetime measurements.…”

The Multifarious Applications of Copper Nanoclusters in Biosensing and Bioimaging and Their Translational Role in Early Disease Detection

“…These noble metals are resistant to corrosion and oxidation, and are inert in the face of non-oxidizing acids, allowing researchers to work on these metals. Amongst all the metals, Au and Ag have been extensively researched in terms of their size-controlled synthesis, intermetallic reaction mechanisms, structural characterization, ligand-induced optical behavior, properties, biological applications, and catalytic performance [ 12 ]. Due to their comparatively simple chemical composition, Cu NCs are easily manipulated for optimization as compared to multicomponent systems (up-conversion nanoparticles and liposomes Cu).…”

“…Optical imaging technology has become a critical research tool in the field of biomedicine, thanks to its ability to visualize biomolecules, cells, tissues, and living organisms in real time and in three dimensions [ 12 ]. Compared with other technologies, optical imaging technology has a number of advantages, including the fact that it is non-invasive and safe, has excellent spatial resolution and visualization capabilities, produces a great volume of data quickly, and is a low-cost method.…”