Enhanced fibronectin adsorption on carbon nanotube/poly(carbonate) urethane: independent role of surface nano-roughness and associated surface energy

The contribution of nanoscale surface roughness on the adsorption of one key cell adhesive protein, fibronectin, on carbon nanotube/poly(carbonate) urethane composites of different surface energies was evaluated. Systematic control of various surface energies by creating different nanosurface roughness features was performed by mixing two promising biomaterials: multi-wall carbon nanotubes and poly(carbonate) urethane. High ratios of carbon nanotubes coated with poly(carbonate) urethane provided for greater hydrophilic surfaces because of higher nanosurface roughness although pure carbon nanotube surfaces were extremely hydrophobic. Fabrication methods followed in this study generated various homogenous nanosurface roughness values (ranging from 2 to 20nm root mean square (RMS) AFM roughness). With the aid of such nanosurface roughness values in composites, a model was developed that linearly correlated nanosurface roughness and associated nanosurface energy to fibronectin adsorption. Specifically, independent contributions of surface chemistry (70%) and surface nano-roughness (30%) were found to mediate fibronectin adsorption. The results of the present study showed why carbon nanotube/poly(carbonate) urethane composites enhance cellular functions and tissue growth by delineating the importance of their physical nano-roughness on promoting the adsorption of a protein well known to be critical for mediating the adhesion of anchorage-dependent cells.     

Protein binding properties of surface-modified porous polyethylene membranes

In this study, we quantified the adsorption of immunoglobulin G (IgG) protein onto several polyelectrolyte-modified sintered porous polyethylene (PPE) membranes. The polymer surfaces had both cationic and anionic charges obtained via the adsorption of polyethylenimine (PEI) and polyacrylic acid (PAA), respectively, onto plasma-activated PPE. The amount of IgG adsorption was determined by measuring the gamma radiation emitted by [125I]-IgG radio labeled protein. By studying the impact of pH and ionic strength on IgG adsorption, we attempted to characterize the role and nature of the electrostatic interactions involved in the adsorption process to better understand how these interactions were influenced by the charge and structure of immobilized polyelectrolyte complexes at modified membrane surfaces. We were able to show that surface modification of PPE membranes with adsorbed PEI monolayers and PEI-PAA bilayers can greatly improve the IgG binding ability of the membrane under optimized conditions. We also showed that the observed improvement in the IgG binding is derived from electrostatic interactions between IgG and the polyelectrolyte surface. In addition, we found that the greatest IgG adsorption occurred when the IgG and the surface possessed predominantly opposite charges, rather than when the surface possessed the greatest electrostatic charge. Finally, we have found that the molecular weight of the terminating polyelectrolyte has a noticeable effect upon the electrostatic interactions between IgG and the PEI-PAA bilayer-modified PPE surfaces.     

Molecular simulation of protein adsorption and desorption on hydroxyapatite surfaces

Protein adsorption and desorption on material surfaces play a key role in the biocompatibility of medical implants, biomineralization and protein separation. In this report, the adsorption and desorption behavior of the 10th type III module of fibronectin (FN-III(10)) with different orientations on hydroxyapatite (HAP) (001) surface were systematically studied by molecular dynamics (MD) and steered MD simulations. These studies show that the electrostatic energy plays a dominant role in the interaction between the model protein and the HAP surface. The values of the interaction energy not only relates to the number of adsorbed sites but also the type. The charged -COO(-) and -NH(3)(+) are the strongest groups that interact with the surface, while other groups like charged guanido group, neutral amino and hydroxyl groups have considerable interactions with the surface. The effects of these groups on interaction energy were quantitatively investigated.     

Platelet adhesion and cellular interaction with poly(ethylene oxide) immobilized onto silicone rubber membrane surfaces

Cellular interaction and platelet adsorption were investigated on poly(ethylene oxide) (PEO) immobilized silicone rubber membrane (SR) which has polyacrylic acid grafts on the surfaces. Polyacrylic acid (PAA) had been introduced to the SR surface after Ar plasma treatment of SR surfaces to introduce peroxide groups. Surface characterizations were made using ATR-FTIR, ESCA, SEM, and contact angle measurements. Experimental results obtained by ESCA high resolution curve fitting spectra indicated that the amount of bisamino PEO of different molecular weights immobilized onto SR surfaces were similar, which showed that the influence of the length of molecular chains (-C-C-O-) on the reactivity of terminal amino group is negligible. The wettability of modified SR surfaces increased with an increase in PEO molecular weight. Biological studies such as corneal epithelial cell culture and blood platelet adhesion were performed to understand the biocompatibility of modified SR surfaces. Biological studies using corneal epithelial cells showed that cell migration, attachment and proliferation onto PEO-20000 immobilized SR surface were suppressed, whereas these biological activities on PEO-600 were enhanced. Another study on platelet adhesion revealed that many platelets attached to PEO-600 immobilized SR, while platelet deposition was rarely observed on SR grafted with PEO-3350. The effects of different PEO molecular chains on biological response were discussed.     

Protein adsorption on polymer surfaces: calculation of adsorption energies

In an attempt to understand the mechanisms of protein adsorption at the solid-liquid interface, we have calculated the interaction potential energy between the protein and the polymer surface by a computer simulation approach. The adsorption of four proteins--lysozyme, trypsin, immunoglobulin Fab, and hemoglobin--on five polymer surfaces was examined. The model polymers used for the calculation were polystyrene, polyethylene, polypropylene, poly(hydroxyethyl methacrylate), and poly(vinyl alcohol). All possible orientations of the protein on the polymer surfaces were simulated and the corresponding interaction energies for the initial contact stage of protein adsorption were calculated. In the calculation of interaction energies, the hydrophobic interaction was not treated explicitly owing to the difficulty in the theoretical treatment. The results showed that the interaction energy was dependent on the orientation of the protein on the polymer surfaces. The energy varied from -850 to +600 kJ/mol with an average of about -155 kJ/mol. The interaction energy was also dependent on the type of polymer. The average interaction energies of the four proteins with poly(vinyl alcohol) were always lower than those with the other polymers. The interaction energy was not dependent on the protein size. It was found that the dispersion attraction played the major role in protein adsorption on neutral polymer surfaces.     

Protein adsorption to poly(ethylene oxide) surfaces.

Surfaces containing poly(ethylene oxide) (PEO) are interesting biomaterials because they exhibit low degrees of protein adsorption and cell adhesion. In this study different molecular weight PEO molecules were covalently attached to poly(ethylene terephthalate) (PET) films using cyanuric chloride chemistry. Prior to the PEO immobilization, amino groups were introduced onto the PET films by exposing them to an allylamine plasma glow discharge. The amino groups on the PET film were next activated with cyanuric chloride and then reacted with bis-amino PEO. The samples were characterized by scanning electron microscopy, water contact angle measurements, gravimetric analysis, and electron spectroscopy for chemical analysis (ESCA). The adsorption of 125I-labeled baboon fibrinogen and bovine serum albumin was studied from buffer solutions. Gravimetric analysis indicated that the films grafted with the low-molecular-weight PEO contained many more PEO molecules than the surfaces grafted with higher-molecular-weight PEO. The high-molecular-weight PEO surfaces, however, exhibited greater wettability (lower water contact angles) and less protein adsorption than the low-molecular-weight PEO surfaces. Adsorption of albumin and fibrinogen to the PEO surfaces decreased with increasing PEO molecular weight up to 3500. A further increase in molecular weight resulted in only slight decreases in protein adsorption. Protein adsorption studies as a function of buffer ionic strength suggest that there may be an ionic interaction between the protein and the allylamine surface. The trends in protein adsorption together with the water contact angle results and the gravimetric analysis suggest that a kind of "cooperative" water structuring around the larger PEO molecules may create an "excluded volume" of the hydrated polymer coils. This may be an important factor contributing to the observed low protein adsorption behavior.     

Protein adsorption on polymer surfaces: calculation of adsorption energies

In an attempt to understand the mechanisms of protein adsorption at the solid-liquid interface, we have calculated the interaction potential energy between the protein and the polymer surface by a computer simulation approach. The adsorption of four proteins-lysozyme, trypsin, immunoglobulin F_ab, and hemoglobin-on five polymer surfaces was examined. The model polymers used for the calculation were polystyrene, polyethylene, polypropylene, poly(hydroxyethyl methacrylate), and poly(vinyl alcohol). All possible orientations of the protein on the polymer surfaces were simulated and the corresponding interaction energies for the initial contact stage of protein adsorption were calculated. In the calculation of interaction energies, the hydrophobic interaction was not treated explicitly owing to the difficulty in the theoretical treatment. The results showed that the interaction energy was dependent on the orientation of the protein on the polymer surfaces. The energy varied from - 850 to + 600 kJ/mol with an average of about - 155 kJ/mol. The interaction energy was also dependent on the type of polymer. The average interaction energies of the four proteins with poly(vinyl alcohol) were always lower than those with the other polymers. The interaction energy was not dependent on the protein size. It was found that the dispersion attraction played the major role in protein adsorption on neutral polymer surfaces.     

椭偏光学显微成像法研究胶原在表面的吸附

我们利用椭偏光学显微成像技术研究了胶原蛋白在亲水疏水表面的吸附,考察了不同pH值、不同吸附时间、不同离子强度以及BSA的存在对胶原在亲水、疏水表面吸附的影响。结果表明,胶原在亲水表面的吸附量在较短时间内即接近于吸附饱和值,而在疏水表面吸附则持续较长时间,最终胶原在疏水表面的吸附量大于在亲水表面的吸附量。胶原在两种表面的吸附量均在pH为7.2时为最大。BSA存在时,疏水表面上BSA对胶原的竞争吸附影响比亲水表面大。     

On the role of CO2 laser treatment in the human serum albumin and human plasma fibronectin adsorption on zirconia (MGO-PSZ) bioceramic surface

The nature of the surface strongly influences the composition and recognizability of the adsorbed protein layer, which in turn affects the subsequent cellular interactions. Thus, to understand the biological response to a material, especially in vitro, one must fully understand the nature of the adsorbed protein film that forms on the material. This study investigates the fundamental interactions between the human serum albumin (no-cell adhesive) and human plasma fibronectin and bioinert ceramic following CO(2) laser treatment. The analysis of the albumin and fibronectin adsorption was conducted on the untreated and CO(2) laser-modified magnesia partially stabilized zirconia (MgO-PSZ) bioceramic using an ellipsometry. It was found that the adsorptions of albumin and fibronectin were influenced by the surface properties. The albumin adsorption was affected by the surface roughness and wettability characteristics of the MgO-PSZ and decreased with these properties, while the fibronectin adsorption was increased with wettability characteristics and predominantly governed by this property. Moreover, the considerable change in the polar component of surface energy, gamma(sv) (p), and its effect on protein adsorption implied that the albumin and fibronectin adsorption on the MgO-PSZ surfaces was probably due to the polar and chemical interactions. The value of this work is to provide a novel technique and useful information for manipulating protein adsorption and thereof cellular interactions.     

Quantitative evaluation of interaction force of fibrinogen at well-defined surfaces with various structures

The effects of functional groups and structures at the surface of biomaterials on protein adsorption were examined using direct interaction force measurements. Three kinds of surface structures were evaluated: polymer brushes, self-assembled monolayers with low molecular weight compounds, and surfaces with conventional polymer coatings. These surfaces had various functional groups including phosphorylcholine (PC) group. The surface characterization demonstrated that surface wettability and flexibility depended on both the structure of the surface and the functional groups at the surface. The interactions of protein with these surfaces were evaluated by a force vs. distance curve using an atomic force microscope (AFM). We used fibrinogen as the protein, and the fibrinogen was immobilized on the surface of the AFM cantilever by a conventional technique. It was observed that the interaction force of fibrinogen was strongly related to surface hydrophobic nature and flexibility. That is, the interaction force increased with the increasing hydrophobic nature of the surface. The relationship between the amount of fibrinogen adsorbed on the surface and the interaction force showed good correlation in the range of fibrinogen adsorption from 0 to 250?ng/cm², that is, in a monolayered adsorption region. The interaction force decreased with increasing surface viscoelasticity. The most effective surface for preventing fibrinogen adsorption was the polymer brush surface with phosphorylcholine (PC) groups, that is, poly(2-methacryloyloxyethyl phosphorylcholine) brush. The interaction force of this sample was less than 0.1?nN and the amount of fibrinogen adsorbed on the surface was minimal. It was found that the evaluation of protein adsorption based on the interaction force measurement is useful for low-protein adsorption surfaces. It was demonstrated that an extremely hydrophilic and flexible surface could weaken the protein interactions at the surface, resulting in greater resistance to protein adsorption.     

Printing patterns of biospecifically-adsorbed protein

The advancement of elastomeric patterning techniques in recent years has significantly enhanced our ability to spatially control biomaterial surface chemistry at the micrometre level. The application of this technology to the patterning of biomolecules onto solid surfaces has created many potential applications including the development of advanced biosensors, combinatorial library screening and the formation of tissue engineering templates. In this paper, we describe the direct patterning of protein by microcontact printing. An important consideration for the fabrication of protein micropatterns intended for these applications is the nature of the protein immobilization to a substrate. To date, the patterning of proteins by direct microcontact printing (microCP) has relied on the non-covalent adsorption to a substrate. Ideally, the proteins need to be firmly anchored onto a surface without adversely effecting their activity. Here, the high affinity avidin-biotin receptor-ligand interaction has been exploited to form arrays of avidin molecules onto a polymeric substrate expressing biotin moieties. This has created a generic technique by which any biotinylated species can be subsequently immobilized into defined patterns. Utilizing atomic force microscopy (AFM), the patterned surfaces have been characterized to molecular resolution. The micropatterned sample supported cell adhesion when biotin-(G)11-GRGDS was bound to the avidin bearing arrays.     

Poly(ethylene oxide)-modified carboxylated polystyrene latices - immobilization chemistry and protein adsorption

α,ω-Diamino poly(ethylene oxides) (PEOs) with different molecular weights (148, 1000, and 3400) were covalently immobilized onto carboxylated polystyrene latices. The immobilization of PEO was carried out with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in aqueous media. The reaction conditions were optimized to obtain a maximal coupling of PEO. The degree of coupling was determined by the surface concentration of amino groups. The maximal surface concentrations of amino groups were close to what is expected for a complete coverage of the surface with PEO. Adsorption of albumin from a buffer solution onto PEO-containing surfaces was about 85% less than the albumin uptake by unmodified polystyrene latices. Protein adsorption from plasma dilutions was lower on surfaces containing PEO molecules with a higher molecular weight. The reduction of the protein uptake from plasma by surfaces containing PEO-3400 molecules was only 40% compared to the adsorption to unmodified surfaces. These results indicate that plasma proteins have a low affinity for surfaces modified with PEO. However the PEO modified surfaces are by no means 'protein resistant' when exposed to plasma.     

Surface modification using silanated poly(ethylene glycol)s

Surface-grafted poly(ethylene glycol) (PEG) molecules are known to prevent protein adsorption to the surface. The protein-repulsive property of PEG molecules are maximized by covalent grafting. We have synthesized silanated monomethoxy-PEG (m-PEG) for covalent grafting of PEG to surfaces with oxide layers. Two different trialkoxysilylated PEGs were synthesized and characterized. The first trialkoxysilylated PEG was prepared by direct coupling of m-PEG with 3-isocyanatopropyltriethoxysilane through a urethane bond (silanated PEG I). The other silanated PEG (silanated PEG II) containing a long hydrophobic domain between PEG and a silane domain was prepared by reacting m-PEG with 1,6-diisocyanatohexane and 10-undecen-1-ol in sequence before silylation with 3-mercaptopropyl trimethoxysilane. Silanated PEGs I and II were grafted onto glass, a model surface used in our study. The PEG-grafted glass surfaces were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Although contact angle did not change much as the bulk concentration of silanated PEG used for grafting increased from 0.1 to 20 mg/ml for both PEGs I and II, the surface atomic concentrations from XPS measurements showed successful PEG grafting. Surface PEG grafting increased concentration of surface carbon but decreased silicone concentration. The high resolution C1s spectra showed higher ether carbon with lower hydrocarbon compositions for the PEG-grafted surfaces compared to the control surface. AFM images showed that more PEG molecules were grafted onto the surface as the bulk concentration used for grafting was increased. AFM images of the dried surfaces showed that the surfaces were not completely covered by PEG molecules. After hydration, however, the surface appears to be covered completely probably due to the hydration of the grafted PEG chains. Glass surfaces modified with silanated PEGs reduced fibrinogen adsorption by more than 95% as compared with the control surface. Silanated PEGs provides a simple method for PEG grafting to the surface containing oxide layers.     

Albumin adsorption onto pyrolytic carbon: a molecular mechanics approach.

A number of implants of cardiac valve prosthesis, vascular prosthesis, and coronary stents present a pyrolytic carbon interface to blood. Plasma protein adsorption is essential for the hemocompatibility of the implanted devices. This work quantitatively evaluates the molecular interaction force between a biomaterial surface (pyrolytic carbon) and plasma protein (albumin) binding sites through a simplified molecular model of the interface consisting of (i) multioriented graphite microcrystallites; (ii) selected fragments of albumin; and (iii) a water environment. A number of simplifying assumptions were made in the calculation: the albumin molecule was divided into hydrophobic and hydrophilic subunits (helices); an idealized clean, nonoxidized polycrystalline graphite surface was assumed to approximate the surface of pyrolytic carbon. The interaction forces between albumin helices and pyrolytic carbon surfaces are evaluated from potential energy data. These forces are decomposed into a normal and a tangential component. The first one is calculated using a docking procedure (F( perpendicular tot MAX) = 4.16 x 10(-20) N). The second one (F( parallel)), calculated by mean of geometric models estimating the energy variation associated with the protein sliding on the material surface, varies within the range +/-9.62 x 10(-21) N. The molecular simulations were performed using the commercial software package Hyperchem 5.0 (Hyperchem, Hypercube, Canada).     

Interaction of calcium and phosphate in apatite coating on titanium with serum albumin

A Ca-deficient carbonate apatite coating on titanium was prepared by pre-calcifying titanium in a saturated Ca(OH)2 solution and then immersing in a supersaturated calcium phosphate solution. The interaction of the protein with the apatite coating on titanium was investigated by scanning electron microscopy with X-ray energy dispersion spectroscopy. X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. During immersion of the coating in bovine serum albumin (BSA) solution, accompanied by an adsorption of BSA onto the coating, calcium and phosphate ions dissolved and reprecipitated, resulting in the formation of the coating containing BSA from the surface to subsurface layers. The adsorption modified the structure and morphology of the apatite coating on titanium and changed the protein configuration. It was also found that the protein chemically adsorbed onto surfaces containing calcium or phosphorus, showed that both Ca and P on the apatite coating were the binding sites with protein. The BSA adsorption onto the coating involved several elements and groups. In this process. Ca played an essential role, and the interaction of Ca on the apatite coating with the protein stimulated the bond of the protein at P sites.     

Self-assembled biomimetic monolayers using phospholipid-containing disulfides

Several phospholipid-based disulfide molecules were synthesized and attached onto the gold-coated silicon wafer using the self-assembling method. The syntheses of these surface-modifying agents were conducted by introducing bromoethylphosphorate (PBr), phosphorylcholine (PC) or phosphorylethanolamine (PE) groups on the terminals of a dialkyl disulfide. After disulfides adsorption onto gold substrate surfaces, the composition, the film thickness, and the conformational order of self-assembled monolayer surfaces were explored and discussed in detail based on reflection-absorption infrared spectroscopy, contact angle measurement, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and so on. The monolayer having the PBr end group could also be converted to a PC surface by treating with trimethylamine. The model functional surfaces of Au-SC11-PC, -PE, -PBr, -OH or corresponding mixed layers were used to mimic biomembrane surfaces. The monolayer having PC groups was found to reduce fibrinogen adsorption as evaluated from protein adsorption experiments using quartz crystal microbalance. It also showed relatively low platelet adherence compare to the glass, PBr and PE surfaces. The cell viability test also revealed that the PC surface displayed lower cytotoxicity than other surfaces.     

A molecular modeling study of the effect of surface chemistry on the adsorption of a fibronectin fragment spanning the 7-10th type III repeats

Although it is well documented that proteins adsorb onto biomaterial surfaces, relatively little is quantitatively understood about the effects of adsorption on protein orientation and conformation. Because this is the primary determining factor of protein bioactivity, the ability to accurately predict a protein's orientation and conformation following adsorption will be essential for the rational design of biomaterial surfaces to control biological responses. Force field-based computational chemistry methods provide an excellent means to theoretically address this issue, with the nontrivial requirement that the force field must be tailored to appropriately represent protein adsorption behavior. Accordingly, we have modified an existing force field (CHARMm) based on semiempirical quantum-mechanical peptide adsorption data to enable it to simulate protein adsorption behavior in an implicit aqueous environment. This modified force field was then applied to predict the adsorption behavior of the 7-10 type III repeats of fibronectin on functionalized surfaces. Predicted changes in adsorption energy and adsorption-induced conformation as a function of surface chemistry were found to correlate well with experimentally observed trends for these same systems. This work represents a first attempt towards the development of a molecular mechanics force field that is specifically parameterized to accurately simulate protein adsorption to biomaterial surfaces.     

Irreversible adsorption of human serum albumin to hydrogel contact lenses: a study using electron spin resonance spectroscopy.

Human serum albumin (HSA) was specifically spin labelled with 4-maleimido-tempo (MSL) at its cysteine 34 residue (HSA-MSL). The irreversible adsorption of HSA-MSL to hydrogel contact lenses (etafilcon A, tefilcon and vifilcon A) was investigated using electron spin resonance (ESR) spectroscopy. Changes in ESR spectral characteristics of adsorbed HSA-MSL as compared to HSA-MSL in solution displayed an additional immobilisation of the spin label due to the adsorption. This immobilisation of MSL corresponds to a large conformational alteration of the HSA-MSL near the modified Cys 34 residue. For both etafilcon A and tefilcon, the rate of irreversible adsorption was relatively slow compared with that of vifilcon A where the maximum state of immobilisation and hence conformational change occurred within the first hour of adsorption. Furthermore, tefilcon produced markedly different ESR spectra where a strong conformational change to a less mobile protein was apparent. This supported a model where the direct irreversible adsorption of HSA from solution dominated on tefilcon as opposed to conversion of the adsorbed protein from the reversible to the irreversible state on both etafilcon A and vifilcon A. HSA-MSL adsorption onto hydrophobic poly(methylmethacrylate) (PMMA) and hydrophilic poly(N-ter-butylacrylamide) (PTBAM) latex beads was also investigated. The spin label MSL was found to be less mobile when HSA was adsorbed onto PMMA compared with PTBAM beads. It was also found that the rate of irreversible adsorption of HSA is far higher onto PMMA surfaces than onto PTBAM surfaces.     

Adsorption of enzymes at the solid-liquid interface. I. Trypsin on polystyrene latex

The enzyme, trypsin, has been used to study conformational changes which occur when protein adsorption onto well-characterized, emulsifier-free, polystyrene latex surface takes place. The adsorption isotherm is of the high affinity, Langmuirian type with plateau adsorption of trypsin of 2.8 mg m-2. The enzymic activity of adsorbed trypsin to low molecular weight substrate is found to decrease as the surface coverage decreases indicating that 'spreading' or unfolding of the native protein conformation, with consequent loss of enzymic activity, occurs. On the close packed surface such 'spreading' is inhibited by steric factors. The view that protein adsorption onto hydrophobic surfaces is dominated by the entropy gain due to protein unfolding to maximize hydrophobic interactions is thus supported.     

Calculation of solvation interaction energies for protein adsorption on polymer surfaces.

Of the interactions that govern protein adsorption on polymer surfaces, solvation interactions (repulsive hydration and attractive hydrophobic interactions) are thought to be among the most important. The solvation interactions in protein adsorption, however, have not been dealt with in theoretical calculation of the adsorption energy owing to the difficulties in modelling such interactions. We have evaluated the solvation interaction energies using the fragment constant method of calculating the partition coefficients of amino acids. The fundamental assumption of this approach is that the partition coefficients of amino acids between water and organic solvent phases are related to the free energies of transfer from bulk water to the polymer surface. The X-ray crystallographic protein structures of lysozyme, trypsin, immunoglobulin Fab, and hemoglobin from the Brookhaven Protein Data Bank were used. The model polymer surfaces were polystyrene, polypropylene, polyethylene, poly(hydroxyethyl methacrylate) [poly(HEMA)], and poly(vinyl alcohol). All possible adsorption orientations of the proteins were simulated to study the effect of protein orientation on the solvation interactions. Protein adsorption on either hydrophobic or hydrophilic polymer surfaces was examined by considering the sum of solvation and other interaction energies. The results showed that the contribution of the solvation interaction to the total protein adsorption energy was significant. The average solvation interaction energy ranged from -259.1 to -74.1 kJ/mol for the four proteins on the hydrophobic polymer surfaces, such as polystyrene, polypropylene, and polyethylene. On the other hand, the average solvation interaction energies on hydrophilic surfaces such as poly(HEMA) and poly(vinyl alcohol) were larger than zero. This indicates that repulsive hydration interactions are in effect for protein adsorption on hydrophilic polymer surfaces. The total interaction energies of the proteins with hydrophobic surfaces were always lower than those with more hydrophilic surfaces. This trend is in agreement with the experimental observations in the literature. This study suggests that consideration of the solvation interaction energies is necessary for accurate calculation of the protein adsorption energies.