Shape dependent protein‐induced stabilization of gold nanoparticles: From a protein corona perspective

Abstract

Gold nanoparticles (AuNPs) are promising materials for many bioapplications. However, upon contacting with biological media, AuNPs undergo changes. The interaction with proteins results in the so‐called protein corona (PC) around AuNPs, leading to the new bioidentity and optical properties. Understanding the mechanisms of PC formation and its functions can help us to utilise its benefits and avoid its drawbacks. To date, most of the previous works aimed to understand the mechanisms governing PC formation and focused on the spherical nanoparticles, although non‐spherical nanoparticles are designed for a wide range of applications in biosensing. In this work, we investigated the differences in PC formation on spherical and anisotropic AuNPs (nanostars in particular) from the joint experimental (extinction spectroscopy, zeta potential and surface‐enhanced Raman scattering [SERS]) and computational methods (the finite element method and molecular dynamics [MD] simulations). We discovered that protein does not fully cover the surface of anisotropic nanoparticles, leaving SERS hot‐spots at the tips and high curvature edges ‘available’ for analyte binding (no SERS signal after pre‐incubation with protein) while providing protein‐induced stabilization (indicated by extinction spectroscopy) of the AuNPs by providing a protein layer around the particle's core. The findings are confirmed from our MD simulations, the adsorption energy significantly decreases with the increased radius of curvature, so that tips (adsorption energy: 2762.334 kJ/mol) would be the least preferential binding site compared to core (adsorption energy: 11819.263 kJ/mol). These observations will help the development of new nanostructures with improved sensing and targeting ability.

Spectroscopic Identification of Charge Transfer of Thiolated Molecules on Gold Nanoparticles via Gold Nanoclusters

“…Incubation of AuNP@Mol with BSA–AuNCs (see Table S4) resulted in the formation of a thin layer of BSA–AuNCs (∼7 nm equal to the size of BSA molecule) on the surface of AuNP@Mol, which can be seen in the TEM image presented in Figure c. This happens due to the binding of BSA on the AuNPs via electrostatic interaction as well as the interaction between disulfide and cysteine groups in BSA and the surface of AuNP (i.e., AuNP@Mol has a pH of 6–7 and AuNCs are in alkaline pH) . The conjugation of BSA-AuNCs to AuNP@Mol nanoparticles was further confirmed by NTA and UV–vis spectroscopy.…”

“…This happens due to the binding of BSA on the AuNPs via electrostatic interaction as well as the interaction between disulfide and cysteine groups in BSA and the surface of AuNP (i.e., AuNP@Mol has a pH of 6−7 and AuNCs are in alkaline pH). 36 The conjugation of BSA-AuNCs to AuNP@ Mol nanoparticles was further confirmed by NTA and UV−vis spectroscopy. An increase in the hydrodynamic sizes of all AuNPs after incubation with BSA−AuNCs as well as a redshift in the LSPR peak of AuNPs indicate the successful adsorption of BSA−AuNCs on the surface of different AuNP@ Mol samples (Figure S4).…”

Shape-Induced Variations in Aromatic Thiols Adsorption on Gold Nanoparticle: A Novel Method for Accurate Evaluation of Adsorbed Molecules

“…In contrast to lower amounts of MBA on AuNS, when MBA is present in excess, MBA most likely rapidly adsorbs on high surface-energy sites including tips which are believed to have superenhanced SERS intensity. The decrease in SERS signal after the initial binding could be associated with the rearrangement of thiols on the surface as schematically illustrated in Figure D with net migration from high-SERS less-stable reactive binding sites (high-curvature areas, such as tips ,, ) to the flatter areas with organization of the MBA into densely packed structures which do not produce as much SERS enhancement. The two-step decrease indicates the complexity of the rearrangement process.…”

Lectin-conjugated nanotags with high SERS stability: selective probes for glycans

“…35 However, citrate molecules that are loosely adsorbed on surface of AuNPs could be replaced with TFMBA molecules due to the strong chemical bond between Au and sulphur (i.e., Au-S bond). 36 When TFMBA is being used in excess, the surface of AuNPs is be fully covered by TFMBA molecules. 37 In this situation, there is a dramatic enhancement in their Raman signal, owing to an enhanced electric field around the AuNPs as well as the formation of an electric dipole under excitation with the 785 nm Raman laser, which is the common laser for biomedical applications 1,35 (Fig.…”

“…36 When TFMBA is being used in excess, the surface of AuNPs is be fully covered by TFMBA molecules. 37 In this situation, there is a dramatic enhancement in their Raman signal, owing to an enhanced electric field around the AuNPs as well as the formation of an electric dipole under excitation with the 785 nm Raman laser, which is the common laser for biomedical applications 1,35 (Fig. S3 †).…”