Nanoparticle size and surface properties determine the protein corona with possible implications for biological impacts

Abstract

Nanoparticles in a biological fluid (plasma, or otherwise) associate with a range of biopolymers, especially proteins, organized into the "protein corona" that is associated with the nanoparticle and continuously exchanging with the proteins in the environment. Methodologies to determine the corona and to understand its dependence on nanomaterial properties are likely to become important in bionanoscience. Here, we study the long-lived ("hard") protein corona formed from human plasma for a range of nanoparticles that differ in surface properties and size. Six different polystyrene nanoparticles were studied: three different surface chemistries (plain PS, carboxyl-modified, and amine-modified) and two sizes of each (50 and 100 nm), enabling us to perform systematic studies of the effect of surface properties and size on the detailed protein coronas. Proteins in the corona that are conserved and unique across the nanoparticle types were identified and classified according to the protein functional properties. Remarkably, both size and surface properties were found to play a very significant role in determining the nanoparticle coronas on the different particles of identical materials. We comment on the future need for scientific understanding, characterization, and possibly some additional emphasis on standards for the surfaces of nanoparticles.

Fig. 1.

Dry pellet formed for carboxyl-modified polystyrene 50-nm particles incubated with increasing plasma concentrations. The error bars represent the difference from two separate experiments. SDS/PAGE for the samples is shown in Table S3.

Fig. 2.

Illustration of SDS/PAGE gels and bands excised. Lanes: 1, 100-nm amine-modified; 2, 50-nm amine-modified; 3, 100-nm plain; 4, 50-nm plain; 5, 100-nm carboxyl-modified; and 6, 50-nm carboxyl-modified. The selected lanes for the different particle types were cut according to the pattern shown to the right of the gels. The numbers to the right of the pattern show the numbering for the proteomic data found in Table S3. The plasma concentrations for the different samples were: 1, 2.8; 2, 0.56; 3, 0.28; 4, 0.56; 5, 0.56; and 6, 5.6 ml of plasma per m² particle surface.

Fig. 3.

Comparison of the overlap in the protein coronas of the different polystyrene particles. Graphs: 1, 100-nm amine-modified; 2, 50-nm amine-modified; 3, 100-nm plain; 4, 50-nm plain; 5, 100-nm carboxyl-modified; and 6, 50-nm carboxyl-modified. The fractions shown are calculated without including different Ig chains. (A–C) Comparison of the similarity between the coronas around different size particles with similar surface properties: fraction of proteins found on both particles (green), and fraction of proteins that is found on one size but not the other (white). (D and E) Comparison of the similarities of the corona for particles of the same size but different surface charges: fraction of proteins found on all three particles (green), fraction of proteins found on the amine-modified and plain particles (blue), fraction of proteins found on the plain and carboxyl-modified particles (yellow), fraction of proteins found on the amine- and carboxyl-modified particles (red), and fraction of proteins found on just one specific particle surface (white).