Revealing the Binding Structure of the Protein Corona on Gold Nanorods Using Synchrotron Radiation-Based Techniques: Understanding the Reduced Damage in Cell Membranes

Abstract

Regarding the importance of the biological effects of nanomaterials, there is still limited knowledge about the binding structure and stability of the protein corona on nanomaterials and the subsequent impacts. Here we designed a hard serum albumin protein corona (BSA) on CTAB-coated gold nanorods (AuNRs) and captured the structure of protein adsorption using synchrotron radiation X-ray absorption spectroscopy, microbeam X-ray fluorescent spectroscopy, and circular dichroism in combination with molecular dynamics simulations. The protein adsorption is attributed to at least 12 Au-S bonds and the stable corona reduced the cytotoxicity of CTAB/AuNRs. These combined strategies using physical, chemical, and biological approaches will improve our understanding of the protective effects of protein coronas against the toxicity of nanomaterials. These findings have shed light on a new strategy for studying interactions between proteins and nanomaterials, and this information will help further guide the rational design of nanomaterials for safe and effective biomedical applications.

Optical Aggregation of Gold Nanoparticles for SERS Detection of Proteins and Toxins in Liquid Environment: Towards Ultrasensitive and Selective Detection

“…Due to the interplay between the 226 electrostatic interaction of molecules surrounding the NRs with the positively charged CTAB bilayer 227 and the destabilization of the CTAB bilayer induced by the PBS at physiological pH, amino acid 228 residues of the protein get in close contact with NRs gold surface [63,64,65,66]. This yields the 229 formation of biomolecule-NRs complexes [65,67] in which individual NRs are stabilized by the 230 protein layer in the solution. The formation of the BIO-NRCs was studied on BSA, which is a protein 231 rich of sulfur spread over 17 disulfides (S-S), 5 methionine (S-CH3) and one free thiol (a cysteine 232 residue) [65].…”

“…This yields the 229 formation of biomolecule-NRs complexes [65,67] in which individual NRs are stabilized by the 230 protein layer in the solution. The formation of the BIO-NRCs was studied on BSA, which is a protein 231 rich of sulfur spread over 17 disulfides (S-S), 5 methionine (S-CH3) and one free thiol (a cysteine 232 residue) [65]. Disulfide bridges contribute to a stable protein tertiary structure as they give solidity 233 the -helix bundles.…”

“…When they interact with gold nanoparticles, the high sulfur affinity with gold 234 causes the disruption of the S-S bridges and the fast creation of the Au-S coordination [68]. As a 235 result, the protein forms a corona all-around the gold nanostructure changing its tertiary structure 236 [65]. Stable colloidal suspensions are obtained if the protein quantity is sufficient to recover the 237 surface and prevent attractive interaction causing precipitation [65].…”

“…As a 235 result, the protein forms a corona all-around the gold nanostructure changing its tertiary structure 236 [65]. Stable colloidal suspensions are obtained if the protein quantity is sufficient to recover the 237 surface and prevent attractive interaction causing precipitation [65]. This is also the case of NRs 238 covered with CTAB.…”

“…When we mix BSA (10 -4 M) in PBS (200 mM in water), the high ionic 239 concentration and the pH value of 7.2 causes the destabilization of the CTAB bilayer surrounding 240 the NRs [63]. The presence of BSA and its fast interaction with the gold surface (they form a stable 241 bound in less than 1 µs [65]) ensures a new protein capping layer that can stabilize the suspension.…”