Dataset Information

ToF-SIMS and XPS Characterization of Protein Films Adsorbed onto Bare and Sodium Styrenesulfonate-Grafted Gold Substrates.

ABSTRACT: The adsorption of single-component bovine serum albumin (BSA), bovine fibrinogen (Fgn), and bovine immunoglobulin G (IgG) films as well as multicomponent bovine plasma films onto bare and sodium styrenesulfonate (NaSS)-grafted gold substrates was characterized. The adsorption isotherms, measured via X-ray photoelectron spectroscopy, showed that at low solution concentrations all three single-component proteins adsorb with higher affinity onto gold surfaces compared to NaSS surfaces. However, at higher concentrations, NaSS surfaces adsorb the same or more total protein than gold surfaces. This may be because proteins that adsorb onto NaSS undergo structural rearrangements, resulting in a larger fraction of irreversibly adsorbed species over time. Still, with the possible exception of BSA adsorbed onto gold, neither surface appeared to have saturated at the highest protein solution concentration studied. Principal component (PC) analysis of amino acid mass fragments from time-of-flight secondary ion mass spectra distinguished between the same protein adsorbed onto NaSS and gold surfaces, suggesting that proteins adsorb differently on NaSS and gold surfaces. Explored further using peak ratios for buried/surface amino acids for each protein, we found that proteins denature more on NaSS surfaces than on gold surfaces. Also, using peak ratios for asymmetrically distributed amino acids, potential structural differences were postulated for BSA and IgG adsorbed onto NaSS and gold surfaces. PC modeling, used to track changes in plasma adsorption with time, suggests that plasma films on NaSS and Au surfaces become more Fgn-like with increasing adsorption time. However, the PC models included only three proteins, where plasma is composed of hundreds of proteins. Therefore, while both gold and NaSS appear to adsorb more Fgn with time, further study is required to confirm that this is representative of the final state of the plasma films.

SUBMITTER: Foster RN

PROVIDER: S-EPMC4821661 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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ToF-SIMS and XPS Characterization of Protein Films Adsorbed onto Bare and Sodium Styrenesulfonate-Grafted Gold Substrates.

Foster Rami N RN Harrison Elisa T ET Castner David G DG

Langmuir : the ACS journal of surfaces and colloids 20160322 13

The adsorption of single-component bovine serum albumin (BSA), bovine fibrinogen (Fgn), and bovine immunoglobulin G (IgG) films as well as multicomponent bovine plasma films onto bare and sodium styrenesulfonate (NaSS)-grafted gold substrates was characterized. The adsorption isotherms, measured via X-ray photoelectron spectroscopy, showed that at low solution concentrations all three single-component proteins adsorb with higher affinity onto gold surfaces compared to NaSS surfaces. However, at ...[more]

PMID: 26977542

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Project description:For immobilization of proteins onto surfaces in a specific and controlled manner, it is important to start with a well-defined surface that contains specific binding sites surrounded by a nonfouling background. For immobilizing histidine-tagged (his-tagged) proteins, surfaces containing nitrilotriacetic acid (NTA) headgroups and oligo(ethylene glycol) (OEG) moieties are a widely used model system. The surface composition, structure, and reactivity of mixed NTA/OEG self-assembled monolayers (SAMs) on Au substrates were characterized in detail using X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and surface plasmon resonance (SPR) biosensoring. XPS results for sequential adsorption of NTA thiols followed by OEG thiols showed that OEG molecules were incorporated into an incompletely formed NTA monolayer until a complete mixed SAM was formed. The surface concentration of NTA headgroups was estimated to be 0.9-1.3 molecule/nm2 in the mixed NTA/OEG monolayers, compared to 1.9 molecule/nm2 in pure NTA monolayers. Angle-dependent XPS indicated NTA headgroups were slightly reoriented toward an upright position after OEG incorporation, and polarization-dependent NEXAFS results indicated increased ordering of the alkane chains of the molecules. Nitrogen-containing and OEG-related secondary ion fragments from the TOF-SIMS experiments confirmed the presence of NTA headgroups and OEG moieties in the monolayers. A multivariate peak intensity ratio was developed for estimating the relative NTA concentration in the outermost (10 A) of the monolayers. SPR measurements of a his-tagged, humanized anti-lysozyme variable fragment (HuLys Fv) immobilized onto Ni(II)-treated mixed NTA/OEG and pure NTA monolayers demonstrated the reversible, site-specific immobilization of his-tagged HuLys Fv (108-205 ng/cm2) with dissociation rates (koff) between 1.0 x 10-4 and 2.1 x 10-5 s-1, both depending on the NTA surface concentration and orientation. The monolayers without Ni(II) treatment exhibited low nonspecific adsorption of his-tagged HuLys Fv (<2 ng/cm2).

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Dataset Information

ToF-SIMS and XPS Characterization of Protein Films Adsorbed onto Bare and Sodium Styrenesulfonate-Grafted Gold Substrates.

Publications

ToF-SIMS and XPS Characterization of Protein Films Adsorbed onto Bare and Sodium Styrenesulfonate-Grafted Gold Substrates.

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