Understanding the nanoparticle–protein corona using methods to quantify exchange rates and affinities of proteins for nanoparticles

Abstract

Due to their small size, nanoparticles have distinct properties compared with the bulk form of the same materials. These properties are rapidly revolutionizing many areas of medicine and technology. Despite the remarkable speed of development of nanoscience, relatively little is known about the interaction of nanoscale objects with living systems. In a biological fluid, proteins associate with nanoparticles, and the amount and presentation of the proteins on the surface of the particles leads to an in vivo response. Proteins compete for the nanoparticle ''surface,'' leading to a protein ''corona'' that largely defines the biological identity of the particle. Thus, knowledge of rates, affinities, and stoichiometries of protein association with, and dissociation from, nanoparticles is important for understanding the nature of the particle surface seen by the functional machinery of cells. Here we develop approaches to study these parameters and apply them to plasma and simple model systems, albumin and fibrinogen. A series of copolymer nanoparticles are used with variation of size and composition (hydrophobicity). We show that isothermal titration calorimetry is suitable for studying the affinity and stoichiometry of protein binding to nanoparticles. We determine the rates of protein association and dissociation using surface plasmon resonance technology with nanoparticles that are thiol-linked to gold, and through size exclusion chromatography of protein-nanoparticle mixtures. This method is less perturbing than centrifugation, and is developed into a systematic methodology to isolate nanoparticle-associated proteins. The kinetic and equilibrium binding properties depend on protein identity as well as particle surface characteristics and size.

Assessing nanoparticle toxicity in cell-based assays: influence of cell culture parameters and optimized models for bridging the in vitro–in vivo gap

“…Finally, it is known that NP can interact with their environment and in most cases avidly bind serum proteins to their surface to form a protein corona 65 . The nature of this corona depends on the physicochemical properties of the NP and on the composition of the microenvironment (e.g.…”

Nanoparticle Adhesion to the Cell Membrane and Its Effect on Nanoparticle Uptake Efficiency

“…[14][15][16] However, NPs dispersed in a biological fluid are rapidly covered by biomolecules, such as proteins and lipids, forming a biomolecular 'corona' that effectively screens the bare NP surface. [17][18][19][20][21][22] When cells are exposed to NPs it is therefore, in realistic circumstances, typically not the bare NP surface that interacts with the cell but the NP-biomolecular corona complex. [23][24][25] Consequently, it becomes interesting to correlate NP uptake not to properties of the bare NP, but to properties of the NP-biomolecular corona complex.…”

Regimes of Biomolecular Ultrasmall Nanoparticle Interactions

“…Firstly, size (in combination with surface) may be used to control, indeed even nearly eliminate, long‐lived interactions between particle and the biomolecular environment. This suggests a transition between the regime where the particle corona identity is relatively fixed3b to one where it fluctuates rapidly. Certainly, this will lead to quite distinct biological outcomes, potentially interpolating between (non‐associating) molecular drug, and more conventional nanoparticle activity, all of which may be “pre‐screened” prior to biological or in vivo studies.…”