Differences In Protein Adsorption Research Articles

Efficacy of a Solution Containing 33% Trichloroacetic Acid and Hydrogen Peroxide in Decontaminating Machined vs. Sand-Blasted Acid-Etched Titanium Surfaces.

This in vitro study assessed the efficacy of a solution containing 33% trichloroacetic acid (CCl3COOH; TCA) and hydrogen peroxide (H2O2) in decontaminating machined (MAC) and sand-blasted acid-etched (SBAE) titanium surfaces. A total of 80 titanium disks were prepared (40 MAC and 40 SBAE). Streptococcus sanguinis and Enterococcus faecalis strains were incubated on 36 samples, while the remaining 44 were kept as controls. Roughness analysis and scanning electron microscopy were used to evaluate the surface features before and after TCAH2O2 treatment. The viability of human adipose-derived mesenchymal stem cells (ASCs) after TCAH2O2 decontamination was assessed with a chemiluminescent assay along with cell morphology through fluorescent staining. TCAH2O2 preserved the surface topography of MAC and SBAE specimens. It also effectively eradicated bacteria on both types of specimens without altering the surface roughness (p > 0.05). Also, no significant differences in protein adsorption between the pristine and TCAH2O2-treated surfaces were found (p = 0.71 and p = 0.94). While ASC proliferation remained unchanged on MAC surfaces, a decrease was observed on the decontaminated SBAE specimens at 24 and 48 h (p < 0.05), with no difference at 72 h (p > 0.05). Cell morphology showed no significant changes after 72 h on both surface types even after decontamination. This study suggests TCAH2O2 as a promising decontamination agent for titanium surfaces, with potential implications for peri-implant health and treatment outcomes.

Altered Proinflammatory Responses to Polyelectrolyte Multilayer Coatings Are Associated with Differences in Protein Adsorption and Wettability.

A full understanding of the relationship between surface properties, protein adsorption, and immune responses is lacking but is of great interest for the design of biomaterials with desired biological profiles. In this study, polyelectrolyte multilayer (PEM) coatings with gradient changes in surface wettability were developed to shed light on how this impacts protein adsorption and immune response in the context of material biocompatibility. The analysis of immune responses by peripheral blood mononuclear cells to PEM coatings revealed an increased expression of proinflammatory cytokines tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1β, monocyte chemoattractant protein (MCP)-1, and interleukin (IL)-6 and the surface marker CD86 in response to the most hydrophobic coating, whereas the most hydrophilic coating resulted in a comparatively mild immune response. These findings were subsequently confirmed in a cohort of 24 donors. Cytokines were produced predominantly by monocytes with a peak after 24 h. Experiments conducted in the absence of serum indicated a contributing role of the adsorbed protein layer in the observed immune response. Mass spectrometry analysis revealed distinct protein adsorption patterns, with more inflammation-related proteins (e.g., apolipoprotein A-II) present on the most hydrophobic PEM surface, while the most abundant protein on the hydrophilic PEM (apolipoprotein A-I) was related to anti-inflammatory roles. The pathway analysis revealed alterations in the mitogen-activated protein kinase (MAPK)-signaling pathway between the most hydrophilic and the most hydrophobic coating. The results show that the acute proinflammatory response to the more hydrophobic PEM surface is associated with the adsorption of inflammation-related proteins. Thus, this study provides insights into the interplay between material wettability, protein adsorption, and inflammatory response and may act as a basis for the rational design of biomaterials.

Mesocellular Silica Foams (MCFs) with Tunable Pore Size as a Support for Lysozyme Immobilization: Adsorption Equilibrium and Kinetics, Biocomposite Properties.

The effect of the porous structure of mesocellular silica foams (MCFs) on the lysozyme (LYS) adsorption capacity, as well as the rate, was studied to design the effective sorbent for potential applications as the carriers of biomolecules. The structural (N2 adsorption/desorption isotherms), textural (SEM, TEM), acid-base (potentiometric titration), adsorption properties, and thermal characteristics of the obtained lysozyme/silica composites were studied. The protein adsorption equilibrium and kinetics showed significant dependence on silica pore size. For instance, LYS adsorption uptake on MCF-6.4 support (pore diameter 6.4 nm) was about 0.29 g/g. The equilibrium loading amount of LYS on MCF-14.5 material (pore size 14.5 nm) increased to 0.55 g/g. However, when the pore diameter was larger than 14.5 nm, the LYS adsorption value systematically decreased with increasing pore size (e.g., for MCF-30.1 was only 0.27 g/g). The electrostatic attractive interactions between the positively charged lysozyme (at pH = 7.4) and the negatively charged silica played a significant role in the immobilization process. The differences in protein adsorption and surface morphology for the biocomposites of various pore sizes were found. The thermal behavior of the studied bio/systems was conducted by TG/DSC/FTIR/MS coupled method. It was found that the thermal degradation of lysozyme/silica composites was a double-stage process in the temperature range 165–420–830 °C.

TiO2 Coating and UV Photofunctionalization Enhance Blood Coagulation on Zirconia Surfaces.

This in vitro study was designed to evaluate the effect of sol-gel derived TiO2 coating on blood coagulation, blood protein adsorption, and platelet response on zirconia surfaces. Square-shaped zirconia (n=96) (10x10x2 mm) was cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n=32) were fabricated: (a) zirconia coated with sol-gel derived TiO2, (b) zirconia coated with sol-gel derived TiO2 and treated with ultraviolet (UV) irradiation for 1 hour, and (c) non-coated zirconia as control. The coatings were prepared from tetraisopropyl orthotitanate solution by dip-coating. The thrombogenicity of the specimens was evaluated using a whole blood kinetic clotting time method where the extent of blood clotting was evaluated at 10, 20, 30, 40, 50, and 60 minutes (n=4/time point, total n=24/group). Scanning electron microscope images were taken to observe platelet morphologies after 1-hour incubation with platelet-rich plasma (PRP) (n=5/group). Surface characteristics were visualized using atomic force microscopy (n=1/group). Adsorption of plasma proteins and fibronectin on each surface was studied by gel electrophoresis (n=2/group). Significant differences were observed in blood coagulation between the test groups at 20-, 30-, 40-, and 50-minute time points (p<0.005). UV treated TiO2 coated specimens showed fastest blood coagulation followed by TiO2 coated and non-coated specimens. Furthermore, platelets appeared at a higher activation state on coated specimens. Gel electrophoresis revealed no difference in protein adsorption among the experimental groups. In summary, TiO2 coatings promoted blood coagulation, and it was further enhanced by UV treatment, which has the potential to hasten the wound healing process in vivo.

The profile of adsorbed plasma and serum proteins on methacrylic acid copolymer beads: Effect on complement activation.

Polymer beads made of 45% methacrylic acid co methyl methacrylate (MAA beads) promote vascular regenerative responses in contrast to control materials without methacrylic acid (here polymethyl methacrylate beads, PMMA). Invitro and invivo studies suggest that MAA copolymers induce differences in macrophage phenotype and polarization and inflammatory responses, presumably due to protein adsorption differences between the beads. To explore differences in protein adsorption in an unbiased manner, we used high resolution shotgun mass spectrometry to identify and compare proteins that adsorb from human plasma or serum onto MAA and PMMA beads. From plasma, MAA beads adsorbed many complement proteins, such as C1q, C4-related proteins and the complement inhibitor factor H, while PMMA adsorbed proteins, such as albumin, C3 and apolipoproteins. Because of the differences in complement protein adsorption, follow-up studies focused on using ELISA to assess complement activation. When incubated in serum, MAA beads generated significantly lower levels of soluble C5b9 and C3a/C3adesarg in comparison to PMMA beads, indicating a decrease in complement activation with MAA beads. The differences in adsorbed protein on the two materials likely alter subsequent cell-material interactions that ultimately result in different host responses and local vascularization.

The effect of elastomer chain flexibility on protein adsorption

Cells are known to respond differently when grown on materials of varying stiffness. However, the mechanism by which a cell senses substrate stiffness is unknown. Lower crosslink density elastomers formed from acrylated star-poly(d,l lactide-co-ϵ-caprolactone) have previously been shown to support higher smooth muscle cell proliferation in in vitro culture. This difference in growth was hypothesized to be due to differences in protein adsorption that resulted from differences in polymer chain mobility at the surface. Therefore, layer mass and viscoelastic properties were measured for HSA, IgG, fibronectin, vitronectin, and serum supplemented media adsorbed to elastomers of two crosslink densities. Significantly more fibronectin adsorbed to the lower crosslink density surface while significantly more IgG adsorbed to the higher crosslink density surface. Furthermore, differences in fibronectin and IgG layer shear moduli were observed, suggesting that there was a difference in the conformation of the adsorbed protein. ATR-FTIR analysis showed that the lower crosslink density elastomer absorbed more surface water. The increased amount of water may cause greater entropic gains upon protein adsorption to the lower crosslink density surface, which increases total protein adsorption from serum and may cause differences in protein conformation and thus cell behavior.

Atomic Force Microscopy and Analytical Ultracentrifugation for Probing Nanomaterial Protein Interactions

Upon contact with the human body, nanomaterials are known to interact with the physiological surroundings, especially with proteins. In this context, we explored analytical methods to provide biologically relevant information, in particular for manufactured nanomaterials as produced by the chemical industry. For this purpose, we selected two batches of SiO(2) nanoparticles as well as four batches of CeO(2) nanoparticles, each of comparably high chemical purity and similar physicochemical properties. Adsorption of serum proteins and bovine serum albumin (BSA) was quantified by SDS-PAGE in combination with densitometry and further investigated by atomic force microscopy (AFM) and analytical ultracentrifugation (AUC). The protein adsorption to SiO(2) nanoparticles was below the limit of detection, regardless of adjusting pH or osmolality to physiological conditions. In contrast, the four CeO(2) nanomaterials could be classified in two groups according to half-maximal protein adsorption. Measuring the work of adhesion and indention by AFM for the BSA-binding CeO(2) nanomaterials revealed the same classification, pointing to alterations in shape of the adsorbed protein. The same trend was also reflected in the agglomeration behavior/dispersibility of the four CeO(2) nanomaterials as revealed by AUC. We conclude that even small differences in physicochemical particle properties may nevertheless lead to differences in protein adsorption, possibly implicating a different disposition and other biological responses in the human body. Advanced analytical methods such as AFM and AUC may provide valuable additional information in this context.

Sequence, structure, and function of peptide self-assembled monolayers.

Cysteine is commonly used to attach peptides onto gold surfaces. Here we show that the inclusion of an additional linker with a length of four residues (-PPPPC) and a rigid, hydrophobic nature is a better choice for forming peptide self-assembled monolayers (SAMs) with a well-ordered structure and high surface density. We compared the structure and function of the nonfouling peptide EKEKEKE-PPPPC-Am with EKEKEKE-C-Am. Circular dichroism, attenuated total internal reflection Fourier transform IR spectroscopy, and molecular dynamics results showed that EKEKEKE-PPPPC-Am forms a secondary structure while EKEKEKE-C-Am has a random structure. Surface plasmon resonance sensor results showed that protein adsorption on EKEKEKE-PPPPC-Am/gold is very low with small variation while protein adsorption on EKEKEKE-C-Am/gold is high with large variation. X-ray photoelectron spectroscopy results showed that both peptides have strong gold-thiol binding with the gold surface, indicating that their difference in protein adsorption is due to their assembled structures. Further experimental and simulation studies were performed to show that -PPPPC is a better linker than -PC, -PPC, and -PPPC. Finally, we extended EKEKEKE-PPPPC-Am with the cell-binding sequence RGD and demonstrated control over specific versus nonspecific cell adhesion without using poly(ethylene glycol). Adding a functional peptide to the nonfouling EK sequence avoids complex chemistries that are used for its connection to synthetic materials.

Cell adhesion on chiral surface: The role of protein adsorption

Chirality is one of the basic, unique, and most appealing features of biological molecules; however, many intriguing chiral phenomena in biological world remains insufficiently revealed yet. In this research, we fabricated chiral surfaces by assembling natural chiral amino acids-cysteine of opposite configurations (D- and L-) onto gold surfaces, respectively, and investigated the adhesion of the L929 fibroblast on them. No significant differences were observed in the density of adherent cells under serum-free culture condition; while in serum-containing condition, significantly more cells adhered on the L-Cys assembled surfaces. This phenomenon suggested that serum protein might play an important role in mediating the selective adhesion of cells on chiral surfaces. Hence, we adopted both radiolabeling and surface plasmon resonance (SPR) techniques to monitor protein adsorption onto the above surfaces. The results evidently showed more proteins adsorbed onto surfaces assembled with L-Cys. We propose that the difference in protein adsorption on chiral surfaces as demonstrated in this paper might not only shed light on the ensuing investigation of bio-related chirality phenomena, but also provide a novel strategy for the rational design and fabrication of novel biomaterials and bio-related devices based on chiral effects.

Effects of thermal treatments on protein adsorption of Co–Cr–Mo ASTM-F75 alloys

Post-manufacturing thermal treatments are commonly employed in the production of hip replacements to reduce shrinkage voids which can occur in cast components. Several studies have investigated the consequences of these treatments upon the alloy microstructure and tribological properties but none have determined if there are any biological ramifications. In this study the adsorption of proteins from foetal bovine serum (FBS) on three Co-Cr-Mo ASTM-F75 alloy samples with different metallurgical histories, has been studied as a function of protein concentration. Adsorption isotherms have been plotted using the surface concentration of nitrogen as a diagnostic of protein uptake as measured by X-ray photoelectron spectroscopy. The data was a good fit to the Langmuir adsorption isotherm up to the concentration at which critical protein saturation occurred. Differences in protein adsorption on each alloy have been observed. This suggests that development of the tissue/implant interface, although similar, may differ between as-cast (AC) and heat treated samples.

Characterization of a calcium phosphate–TiO 2 nanotube composite layer for biomedical applications

Well-ordered nanotube arrays of titania ~ 0.7 μm high and about 40 or 110 nm in diameter were prepared via electrochemical oxidation at constant voltage (10, 15, 20 or 25 V) in a mixture of 0.86 wt.% of NH 4F, glycerol and deionized water. The effect of annealing the nanotubes at 600 °C on their morphology and structure was examined using SEM and TEM techniques. These substrates are suitable supports for a calcium phosphate coating deposited by a simple immersion in Hank solution. The nucleation and growth of a calcium phosphate (Ca–P) coating deposited on TiO 2 nanotubes (NT) from Hanks' solution was investigated using SEM. XPS and FTIR surface analytical techniques were used to characterize the self-organized porous TiO 2 layers covered with calcium phosphate coatings before and after protein adsorption. Our results confirm that the nanotubular titania layer became stable after annealing at 600 °C, while its internal structure changed from amorphous to crystalline anatase, and eventually, a mixture of anatase and rutile. These thermally stabilized TiO 2 nanotubes significantly enhance apatite formation in Hanks' Balanced Salt Solution as compared to pure Ti covered with a native oxide layer. The Ca–P/TiO 2 NT/Ti surface adsorbs a higher amount of protein (bovine serum albumin, BSA) for a geometric surface area than does the Ti surface. The above difference in protein adsorption suggests a more promising initial cellular response for a Ca–P/TiO 2 NT/Ti composite than for a typical Ti implant surface.

Preparation of superhydrophilic microrough titanium implant surfaces by alkali treatment

A new strategy to render intrinsically hydrophobic microrough titanium implant surfaces superhydrophilic is reported, which is based on a rapid treatment with diluted aqueous sodium hydroxide solutions. The physicochemical characterization and protein interaction of the resulting superhydrophilic implant surfaces are presented. The superhydrophilicity of alkali treated microrough titanium substrates was mainly attributed to deprotonation and ion exchange processes in combination with a strong enhancement of wettability due to the roughness of the used substrates. Albeit these minor and mostly reversible chemical changes qualitative and quantitative differences between the protein adsorption on untreated and alkali treated microrough titanium substrates were detected. These differences in protein adsorption might account for the enhanced osseointegrative potential of superhydrophilic alkali treated microrough implant surfaces. The presented alkali treatment protocol represents a new clinically applicable route to superhydrophilic microrough titanium substrates by rendering the implant surface superhydrophilic "in situ of implantation".

Interaction of plasma proteins with commercial protein repellent polyvinyl chloride (PVC): a word of caution

Protein adsorption onto polymers remains a problem. In recent years, several protein-repellent PVC tubings have been developed. Although several studies report the interaction between plasma coagulation proteins and PVC, few address the interaction with other plasma proteins. Two commercial brands of untreated medical grade PVC tubing, phosphorylcholine-coated PVC tubing, triblock-copolymer (polycaprolactone-polydimethylsiloxane-polycaprolactone)-treated PVC tubing and poly-2-methoxyethylacrylate (PMEA)-coated tubing were exposed for 60 minutes to human plasma. A broad spectrum of plasma proteins was found on all tubing. The adsorbed albumin to total protein ratio is lower than the similar ratio in plasma while alpha1 and alpha2 globulins are over-represented in the protein spectrum. On PMEA tubing, not only alpha globulins, but also beta and gamma globulins, are found in high concentrations in the adsorbed protein. PMEA tubing and uncoated PVC tubing of brand B had a higher amount of protein adsorbed compared against all other tubing (p < 0.05). There were no statistical differences in protein adsorption between the triblock-copolymer-treated tubing, the phosphorylcholine-coated tubing and the uncoated PVC tubing of brand A. The average thickness of the protein layer was 23 nm. Plasma protein adsorption still exists on uncoated and protein-repellent tubing and can initiate a systemic inflammatory reaction.

Quantification of Surface-Bound Proteins by Fluorometric Assay: Comparison with Quartz Crystal Microbalance and Amido Black Assay

Protein adsorption is of major and widespread interest, being useful in the fundamental understanding of biological processes at interfaces through to the development of new materials. A number of techniques are commonly used to study protein adhesion, but few are directly quantitative. Here we describe the use of Nano Orange, a fluorometric assay, to quantitatively assess the adsorption of bovine fibrinogen and albumin onto model hydrophilic (OH terminated) and hydrophobic (CH3 terminated) surfaces. Results obtained using this method allowed the calibration of previously unquantifiable data obtained on the same surfaces using quartz crystal microbalance measurements and an amido black protein assay. Both proteins were found to adsorb with higher affinity but with lower saturation levels onto hydrophobic surfaces. All three analytical techniques showed similar trends in binding strength and relative amounts adsorbed over a range of protein concentrations, although the fluorometric analysis was the only method to give absolute quantities of surface-bound protein. The versatility of the fluorometric assay was also probed by analyzing protein adsorption onto porous superhydrophobic and superhydrophilic surfaces. Results obtained using the assay in conjunction with these surfaces were surface chemistry dependent. Imbibition of water into the superhydrophilic coatings provided greater surface area for protein adsorption, although the protein surface density was less than that found on a comparable flat hydrophilic surface. Superhydrophobic surfaces prevented protein solution penetration. This paper demonstrates the potential of a fluorometric assay to be used as an external calibration for other techniques following protein adsorption processes or as a supplemental method to study protein adsorption. Differences in protein adsorption onto hydrophilic vs superhydrophilic and hydrophobic vs superhydrophobic surfaces are highlighted.

Surface functionalized titanium thin films: Zeta-potential, protein adsorption and cell proliferation

The relationship between electric charge at a material surface and protein adsorption is essential to understand the mechanism of biological integration of materials with tissues. This study investigated the influence of titanium thin films’ surface chemistry and surface electric charge (zeta-potential) properties on protein adsorption and cell proliferation. Titanium thin films were surface functionalized with different functional end groups, such as CH CH 2, NH 2 and COOH groups in order to produce surfaces with a variety of electric charge properties. The chemical compositions, electric charges and wettability were investigated by using X-ray photoelectron spectroscopy (XPS), zeta-potential measurements and water contact angle measurements, respectively. XPS revealed the surface functionalization of titanium films with CH CH 2, NH 2, and COOH groups, which were converted from CH CH 2 groups. Ti COOH samples showed the lowest water contact angles and zeta-potential compared to all other samples investigated in this study. NH 2-terminated titanium films displayed intermediate contact angles of 70.3 ± 2.5°. Fibrinogen adsorption on titanium films and surface functionalized titanium films were investigated in this study. Ti–COOH samples displayed a lower protein adsorption than all other groups, such as NH 2 , CH CH 2-terminated titanium thin films. A tendency that the lower zeta-potential of the samples, the lower the protein adsorption at their surfaces was observed. In vitro cell proliferation tests were also performed on the different surface functionalized titanium films. NH 2-terminated titanium films displayed good cell proliferation and cell viability tendency. However, a lower cell proliferation on COOH-terminated titanium films was observed compared with NH 2-terminated titanium films. This effect was attributed to the difference in protein adsorption of these samples.

Biological responses to cationically charged phosphorylcholine-based materials in vitro

Phosphorylcholine (PC)-based polymers have been used in a variety of medical device applications to improve biocompatibility. The use of PC-based materials for biomaterials is associated with low protein adsorption, reduced complement activation, low inflammatory response and cell adhesion. For some medical device applications however, materials that support cell adhesion are also beneficial, allowing host interaction and encouraging full incorporation within the body. As previous studies have suggested that cell adhesion to materials is enhanced by the addition of charge, PC-based polymers have therefore been modified to incorporate various concentrations of cationic charge. In this study, the affect of cationic charge on a range of biological responses was investigated. In vitro assays have been used to assess the adsorption of protein onto the materials surface, the adhesion of mouse fibroblasts and rabbit corneal epithelial cells and the adhesion of human mononuclear cells and granulocytes. The results corroborate previous work showing that PC without charge significantly reduces protein adsorption, cell adhesion and inflammatory cell activation. The addition of cationic charge to PC polymers however, resulted in an increase in all of the above responses. This increase did not however, increase linearly with cationic monomer concentration. The differences in cell adhesion are discussed in terms of differences in protein adsorption, cytotoxicity and/or stability of the different cationic polymer coatings.

Adsorption of endotoxins on glass in the presence of cationic proteins.

Endotoxin activity was detected in empty glass tubes where endotoxins were incubated with lysozyme, histone or RNaseA, indicating adsorption of endotoxins on glass in the presence of cationic proteins. In the case of lysozyme, the recovery of spiked endotoxins (90.0%) using polystyrene tubes for incubation was much greater than the recovery (28.5%) using glass tubes, suggesting that lysozyme-mediated adsorption of endotoxins on glass is a major cause of poor recovery of spiked endotoxins in the LAL assay using glass tubes. In contrast, the recovery of spiked endotoxins (64.7%) using polystyrene tubes in the presence of the non-cationic protein BSA was less than the recovery (103.9%) using glass tubes. The difference in endotoxin recovery using glass or polystyrene tubes in the presence of cationic proteins or BSA can be explained by differences in protein adsorption on the tubes. Consequently, care must be exercised in selecting containers used for the LAL assay of proteins which bind to endotoxins.

Protein adsorption in glutaraldehyde-preserved bovine pericardium and porcine valve tissues

Background. Proteins adsorbed by bioprosthetic tissues after implantation play a major role in the process of calcification. We investigated whether there are differences in protein adsorption between bovine pericardial and porcine valvular tissues that could correlate with the differences observed clinically.Methods. Glutaraldehyde-treated bovine pericardial and porcine valve samples were implanted subcutaneously in rats and retrieved 1 month after implantation. Total protein content was assessed by Lowry’s method. Qualitative analysis was performed by polyacrylamide gel electrophoresis. Quantitative analysis was performed by densitometry.Results. Total protein content showed a higher protein concentration in porcine valve tissue than in pericardialtissue: 149 ± 22.6 μg/mg dry tissue versus 108 ± 12.7 μg/mg dry tissue (38% increase). In pericardial tissue, four protein bands (17, 16, 15.5, and 13.5 kd) showed decreased concentration when compared with porcine valve tissue, whereas one band (11 kd) showed increased concentration.Conclusions. Significant differences were found in protein content between bovine pericardial and porcine valve tissues. Correlations with clinical findings may lead to a better understanding of the mechanism involved in the process of calcification, particularly the role played by the structure of the tissues.

Analysis of plasma protein adsorption on polymeric nanoparticles with different surface characteristics.

Plasma protein adsorption patterns on colloidal drug carriers acquired after i.v. administration depend on their surface characteristics and are regarded as key factors for their in vivo organ distribution. Polymeric latex particles with strongly differing surface properties were synthesized as models for colloidal drug carriers for tissue-specific drug targeting via the intravenous route. Physicochemical characterization was performed for size, surface charge density, zeta potential, and surface hydrophobicity. The interactions with human plasma proteins were studied by way of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Considerable differences in protein adsorption on the latex particles were detected with regard to the total amount of surface-bound protein on the various particle types as well as specific proteins adsorbed, for example, fibrinogen, albumin, and a recently identified plasma glycoprotein. Possible correlations between protein adsorption patterns and the physicochemical characteristics and topography of the polymeric surfaces are shown and discussed. Knowledge about protein-nanoparticle interactions can be utilized for the rational design of colloidal drug carriers and also may be useful for optimizing implants and medical devices.

Surfaces modified with PEO by the Williamson reaction and their affinity for proteins

Poly(ethylene oxide) (PEO) was immobilized by the Williamson ether synthesis onto halogenated surfaces such as poly(vinylidene chloride), surface-brominated polypropylene, and surface-brominated poly(ethylene terephthalate). PEO (Mw 20,000) was converted to its sodium salt and reacted for various times with the halogen-containing surfaces at 95°C in the melt, or as a solution in 2-methoxyethyl ether. X-ray photon spectroscopy and water contact-angle measurements confirmed the surface-immobilization of PEO. The adsorption from phosphate buffer of human serum albumin, immunoglobulin G (IgG) and fibrinogen, and murine IgG was reduced after modification of the surfaces. In addition, IgG adsorption from pooled human sera was diminished. The difference in protein adsorption between test samples and controls exhibited a strong dependence on input protein concentration. © 1997 John Wiley & Sons, Inc.