Characteristics of the media used to disperse PAA NPs and silica NPs.

<p>Characteristics of the media used to disperse PAA NPs and silica NPs.</p

Relative abundance of proteins identified in samples of silica NPs dispersed in different media.

<p>Silica NPs were dispersed in different media and incubated for 1h in 10% or 100% FBS. Proteins were separated from NPs, analysed on SDS-PAGE and identified by MS. Spectral counts were used as a measure of individual protein in a sample. Legend is further explained in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169552#pone.0169552.t003" target="_blank">Table 3</a>. The differences in protein corona composition of silica NPs dispersed in PBS, NaCl and RPMI-1640 were significant compared to protein corona of silica NPs dispersed in dH2O (p < 0.05).</p

Relative abundance of proteins identified in samples of PAA NPs dispersed in different media.

<p>PAA NPs were dispersed in different media and incubated for 1h in 10% or 100% FBS. Proteins were separated from NPs, analysed on SDS-PAGE and identified by MS. Spectral counts were used as a measure of individual protein in a sample. Legend is further explained in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169552#pone.0169552.t003" target="_blank">Table 3</a>. The differences in protein corona composition of PAA NPs dispersed in PBS, NaCl and RPMI-1640 were significant compared to protein corona of PAA NPs dispersed in dH2O (p < 0.05).</p

FTIR measurements.

<p>Samples were dried on the diamond crystal from solutions/dispersions prior to ATR-FTIR measurements. A: ATR-FTIR spectra of cobalt ferrite NPs (Co ferrite NPs), PAA, PAA NPs and silica NPs. B: ATR-FTIR spectra of cobalt ferrite NPs (Co ferrite NPs), PAA, and PAA NPs in the 1900–900 cm^-1 region. C: ATR-FTIR spectrum of silica NPs in the 4000–600 cm^-1 region.</p

Dispersion of Nanoparticles in Different Media Importantly Determines the Composition of Their Protein Corona

<div><p>Protein corona of nanoparticles (NPs), which forms when these particles come in to contact with protein-containing fluids, is considered as an overlooked factor in nanomedicine. Through numerous studies it has been becoming increasingly evident that it importantly dictates the interaction of NPs with their surroundings. Several factors that determine the compositions of NPs protein corona have been identified in recent years, but one has remained largely ignored—the composition of media used for dispersion of NPs. Here, we determined the effect of dispersion media on the composition of protein corona of polyacrylic acid-coated cobalt ferrite NPs (PAA NPs) and silica NPs. Our results confirmed some of the basic premises such as NPs type-dependent specificity of the protein corona. But more importantly, we demonstrated the effect of the dispersion media on the protein corona composition. The differences between constituents of the media used for dispersion of NPs, such as divalent ions and macromolecules were responsible for the differences in protein corona composition formed in the presence of fetal bovine serum (FBS). Our results suggest that the protein corona composition is a complex function of the constituents present in the media used for dispersion of NPs. Regardless of the dispersion media and FBS concentration, majority of proteins from either PAA NPs or silica NPs coronas were involved in the process of transport and hemostasis. Interestingly, corona of silica NPs contained three complement system related proteins: complement factor H, complement C3 and complement C4 while PAA NPs bound only one immune system related protein, α-2-glycoprotein. Importantly, relative abundance of complement C3 protein in corona of silica NPs was increased when NPs were dispersed in NaCl, which further implies the relevance of dispersion media used to prepare NPs.</p></div

List of serum proteins found in the corona of PAA and silica NPs.

<p>List of serum proteins found in the corona of PAA and silica NPs.</p

NPs protein coronas by theoretical pI of their constituting proteins.

<p>PAA (A, B) and silica (C, D) NPs were dispersed in different media and incubated for 1 h in 10% (A, C) or 100% (B, D) FBS. Proteins constituting NPs coronas were separated by SDS-PAGE and identified by MS. Theoretical pIs were calculated using Compute pI/Mw tool from the ExPASy portal.</p

Analysis of NPs protein corona using SDS-PAGE.

<p>PAA (A) and silica (B) NPs were dispersed in different media (dH₂O, NaCl, PBS, RPMI) and incubated for 1 h in 10% or 100% FBS. Samples denoted with (+) contained PAA (A) or silica (B) NPs. In samples without NPs (-) were the proteins which adhered to plastic despite thorough washing. Only the bands that were different in respective test and control sample (mobbed red) were excised and analysed by MS. M denotes lanes loaded with molecular mass standards. Molecular mass is given in kDa.</p

Characterization of PAA NPs and silica NPs in different dispersion media with or without 10% FBS.

<p>Z-average size, hydrodynamic diameter, PDI values, and zeta potential are presented. Statistically significant differences determined for different media compared to samples in dH2O are denoted with an asterisk.</p

NPs protein coronas by Gene Ontology (GO) biological process of constituting proteins.

<p>PAA (A, B) and silica (C, D) NPs were dispersed in different media and incubated for 1h in 10% (A, C) or 100% (B, D) FBS. Proteins forming corona of NPs were separated by SDS-PAGE and characterized by MS. GO information was acquired from the UniProt database.</p