Protein Adsorption onto Silica Nanoparticles:  Conformational Changes Depend on the Particles' Curvature and the Protein Stability

Abstract

We have analyzed the adsorption of protein to the surfaces of silica nanoparticles with diameters of 6, 9, and 15 nm. The effects upon adsorption on variants of human carbonic anhydrase with differing conformational stabilities have been monitored using methods that give complementary information, i.e., circular dichroism (CD), nuclear magnetic resonance (NMR), analytical ultracentrifugation (AUC), and gel permeation chromatography. Human carbonic anhydrase I (HCAI), which is the most stable of the protein variants, establishes a dynamic equilibrium between bound and unbound protein following mixture with silica particles. Gel permeation and AUC experiments indicate that the residence time of HCAI is on the order of approximately 10 min and slowly increases with time, which allows us to study the effects of the interaction with the solid surface on the protein structure in more detail than would be possible for a process with faster kinetics. The effects on the protein conformation from the interaction have been characterized using CD and NMR measurements. This study shows that differences in particle curvature strongly influence the amount of the protein's secondary structure that is perturbed. Particles with a longer diameter allow formation of larger particle-protein interaction surfaces and cause larger perturbations of the protein's secondary structure upon interaction. In contrast, the effects on the tertiary structure seem to be independent of the particles' curvature.

Immunomodulatory properties of silver nanoparticles contribute to anticancer strategy for murine fibrosarcoma

“…37 This NP-PC formation is aided by several forces, such as hydrogen bonds, solvation forces, van der Waals interaction, and others. 38,39 Nanoparticles can also modify the structure and therefore, the function of the adsorbed proteins in NP-PCs, which thus alter the overall activity of the nanoparticles. This modification of the adsorbed proteins in NP-PCs may involve specific foldings, which may lead to a change in the conformation of the epitopes of the adsorbed protein.…”

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO2 Nanoparticles

“…[60][61][62] Physical parameters such as the surface curvature of NPs were proposed to play a role in the competitive adsorption of proteins in the process, resulting in the formation of the hard corona. 22 It could be of interest to investigate the possible contribution of different amounts and distributions of surface silanols to the composition of the hard protein corona on SiO 2 NPs. To the best of our knowledge, the formation of a protein corona on pyrolytic silica NPs has not been investigated yet.…”

Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

“…13 Protein adsorption on nanoparticles can be affected by the high surface curvature of the particles. [14][15][16][17] Much attention was paid to the question to what extent the structure of proteins is perturbed by adsorption onto hydrophilic or hydrophobic nanoparticles, [17][18][19] or if the interaction with their strongly curved surface can promote aggregation and brillation of proteins. 20,21 On the other hand, it is also possible that the adsorption of the protein causes bridging of two or more nanoparticles.…”