Quantitative analysis of the protein corona on FePt nanoparticles formed by transferrin binding

Abstract

Nanoparticles are finding a rapidly expanding range of applications in research and technology, finally entering our daily life in medical, cosmetic or food products. Their ability to invade all regions of an organism including cells and cellular organelles offers new strategies for medical diagnosis and therapy (nanomedicine), but their safe use requires a deep knowledge about their interactions with biological systems at the molecular level. Upon incorporation, nanoparticles are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a 'protein corona'. These nanoparticle -protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here we have quantitatively analysed the adsorption of human transferrin onto small (radius approx. 5 nm) polymer-coated FePt nanoparticles by using fluorescence correlation spectroscopy. Transferrin binds to the negatively charged nanoparticles with an affinity of approximately 26 mM in a cooperative fashion and forms a monolayer with a thickness of 7 nm. By using confocal fluorescence microscopy, we have observed that the uptake of FePt nanoparticles by HeLa cells is suppressed by the protein corona compared with the bare nanoparticles.

Dissociation coefficients of protein adsorption to nanoparticles as quantitative metrics for description of the protein corona: A comparison of experimental techniques and methodological relevance

“…The resulting data set d h (c(P)) of hydrodynamic diameters determined at different protein concentrations c(P) can be fitted with the Hill model, yielding the protein concentration in which half of the NP surface is saturated with protein K' D , the maximum number N max of proteins which can be bound per NP, and the Hill coefficient n [11]. The group of Nienhaus et al has used such FCS measurements to determine protein adsorption of several proteins to different NP surfaces [21,24,26,[40][41][42][43][44][45]. Notably FCS measurements can be performed in situ, i.e.…”

Interaction of colloidal nanoparticles with their local environment: the (ionic) nanoenvironment around nanoparticles is different from bulk and determines the physico-chemical properties of the nanoparticles

“…The more protein molecules are adsorbed on the NP surface, the bigger the size of each NP becomes [29,41,42]. In the case of highly colloidal stable NPs with narrow size distribution, it was shown that in solutions with only one type of protein (such as for example human bovine serum [29,43] or transferrin [30,44]) adsorbed proteins under saturation conditions form a monolayer on top of the NP surface. Often, interaction of proteins with NPs is unwanted and thus needs to be circumvented.…”

“…interaction between NPs and proteins [28]) affects both, the NPs, as well as their local environment. Adsorbed proteins clearly change two key parameters of NPs: their hydrodynamic diameter [29,30] and in many cases also their colloidal stability [31][32][33]. On the other hand, the NPs may also affect (some types of ) adsorbed proteins, in particular via structural changes, which may lead to dysfunction of the proteins [34 -36].…”

Effects of the Presence or Absence of a Protein Corona on Silica Nanoparticle Uptake and Impact on Cells

“…[23][24][25][26][27][28][29] In particular, even though the details of the uptake mechanisms are still unresolved (indeed, details are still missing even for nanoparticles exposed to cells in presence of serum), [30][31] it has been observed that nanoparticle uptake in serum free conditions is, in most cases, higher than what measured for the same nanoparticle in the presence of serum, [23][24][25][26][27] or also a more simple protein solution (such as for instance what observed for FePt nanoparticles in the presence of albumin or transferrin). 29 Moreover, different reports have shown that nanoparticle impact is also affected by the presence or absence of a protein coating (or other coatings) on their surface, and that the presence of a corona in serum can mitigate the toxicity of the bare materials. [32][33][34][35][36] In order to further explain and to connect these different outcomes, we have studied how uptake and impact of silica nanoparticles in A549 lung epithelial cells are affected by the presence or the absence of a pre-formed corona in serum.…”