Direct observation of interaction between proteins and blood-compatible polymer surfaces (original) (raw)
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Biomaterials, 2000
Platelet adhesion and spreading is suppressed when a poly(2-methoxyethylacrylate) (PMEA) surface is used, compared with other polymer surfaces. To clarify the reason for this suppression, the relationship among the amount of the plasma protein adsorbed onto PMEA, its secondary structure and platelet adhesion was investigated. Poly(2-hydroxyethylmethacrylate) (PHEMA) and polyacrylate analogous were used as references. The amount of protein adsorbed onto PMEA was very low and similar to that absorbed onto PHEMA. Circular dichroism (CD) spectroscopy was applied to examine changes in the secondary structure of the proteins after adsorption onto the polymer surface. The conformation of the proteins adsorbed onto PHEMA changed considerably, but that of proteins adsorbed onto PMEA di!ered only a little from the native one. These results suggest that low platelet adhesion and spreading are closely related to the low degree of the denaturation of the protein adsorbed onto PMEA. PMEA could be developed as a promising material to produce a useful blood-contacting surface for medical devices.
Journal of Colloid and Interface Science, 1986
The adsorption of proteins to polymers is typically irreversible. Even the use of detergents does not elute all the adsorbed protein from all polymers. The fundamental reasons for such apparently tight protein binding are not well understood, so a study of several aspects of elution was undertaken. A method for examining the interaction of proteins at the protein/polymer interface using SDS elutability as a measure of the protein-surface interaction strength was developed. The effects of polymer type, elution agent, elution conditions, protein type, protein concentration, sample age, and storage temperature on elutability were examined. The results show that protein elutability from polymers decreases slowly over a period of days at 4°C but proceeds much more rapidly at elevated temperatures. The results indicate that protein denaturation may be responsible for both the initial incomplete elution and the decreases in SDS elutability of fibrinogen and albumin from polymers with time.
Langmuir, 2006
Interaction forces between surfaces designed to be protein resistant and fibrinogen (Fg) were investigated in phosphatebuffered saline with colloid probe atomic force microscopy. The surfaces of the silica probes were coated with a layer of fibrinogen molecules by adsorption from the buffer. The technique of low-power, pulsed AC plasma polymerization was used to make poly(ethylene glycol) (PEG)-like coatings on poly(ethylene teraphthalate) by using diethylene glycol vinyl ether as the monomer gas. The degree of PEG-like nature of the films was controlled by use of a different effective plasma power in the chamber for each coating, ranging from 0.6 to 3.6 W. This produced a series of thin films with a different number of ether carbons, as assessed by X-ray photoelectron spectroscopy. The interaction force measurements are discussed in relation to trends observed in the reduction of fibrinogen adsorption, as determined quantitatively by 125 I radio-labeling. The plasma polymer coatings with the greatest protein-repelling properties were the most PEG-like in nature and showed the strongest repulsion in interaction force measurements with the fibrinogen-coated probe. Once forced into contact, all the surfaces showed increased adhesion with the protein layer on the probe, and the strength and extension length of adhesion was dependent on both the applied load and the plasma polymer surface chemistry. When the medium was changed from buffer to water, the adhesion after contact was eliminated and only appeared at much higher loads. This indicates that the structure of the fibrinogen molecules on the probe is changed from an extended conformation in buffer to a flat conformation in water, with the former state allowing for stronger interaction with the polymer chains on the surface. These experiments underline the utility of aqueous surface force measurements toward understanding protein-surface interactions, and developing nonfouling surfaces that confer a steric barrier against protein adsorption.
Blood compatibility of surfaces with superlow protein adsorption
Biomaterials, 2008
In this work, five self-assembled monolayers (SAMs) and three polymeric brushes with very low fibrinogen adsorption were prepared. The five SAMs are oligo(ethylene glycol) (OEG), phosphorylcholine (PC), oligo(phosphorylcholine) (OPC), and two mixed positively and negatively charged SAMs of SO 3 À / N þ (CH 3 ) 3 (SA/TMA) and COO À /N þ (CH 3 ) 3 (CA/TMA). Three polymer brushes were prepared on gold surfaces via surface-initiated atom transfer radical polymerization (ATRP) using three monomers, sulfobetaine methacrylate (SBMA), carboxybetaine methacrylate (CBMA), and oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Surface plasmon resonance (SPR) measurements show that although all of these surfaces are ''nonfouling'' to fibrinogen adsorption from buffer solution, their protein adsorption from undiluted human blood plasma varies widely. Polymer brushes exhibit much lower protein adsorption from plasma than any of the five SAMs tested. However, platelet adhesion measurements on plasma-preadsorbed surfaces show that all of these surfaces have very low platelet adhesion. Clotting time measurements using recalcified platelet poor plasma (PPP) incubation with the eight types of surfaces show that they do not shorten clotting times. Linear polymers of polySBMA and polyCBMA with similar molecular weights were also synthesized and characterized. In the presence of polyCBMA linear polymers, the clotting time of PPP was prolonged and increased with the concentration of the polymer, while no anticoagulant activity was observed for the polySBMA or PEG polymers. The unique anticoagulant activity of polyCBMA, as well as its high plasma protein adsorption resistance, makes polyCBMA a candidate for blood-contacting applications.
Effect of Preadsorbed Proteins on Cell Adhesion to Polymer Surfaces
Journal of Colloid and Interface Science, 1993
Adsorption of three different proteins and adhesion of cells onto various substrates in the presence of serum proteins were studied. Both the maximal protein adsorption and the maximal cell adhesion were observed on surfaces with water contact angle around 70°. Preadsorption of serum albumin prevented cell adhesion to all the substrates, whereas preadsorbed fibronectin (FN) enhanced cell adhesion to all the substrates, independent of their water wettability, except for poly(vinyl alcohol) and acrylamide-grafted films. Competitive adsorption of FN from mixed proteins, ranging from 0.03 to 0.07 p.g/cm2 , markedly influenced cell adhesion in the presence of serum. These results suggest that the effect of the water wettability of surfaces on cell adhesion in the presence of serum should occur through protein layers adsorbed directly to the substrate surfaces. ©1993 Academic Press, inc.
Journal of Biomaterials and Nanobiotechnology, 2012
Plasma proteins influence the initial adhesion of bacteria to biomaterials as well as interactions between bacteria and blood platelets on blood-contacting medical devices. In this paper, we study the effects of three human plasma proteins, albumin, fibrinogen (Fg), and fibronectin (Fn), on the adhesion of Staphylococcus epidemidis RP62A to polyurethane biomaterial surfaces, and also address how these three proteins affect bacterial interactions with human platelets on materials. Measurements of bacterial adhesion on polymer surfaces pre-adsorbed with a variety of proteins demonstrate that Fn leads to increased bacterial adhesion, with the order of effectiveness being Fn Fg > albumin. Immuno-AFM (atomic force microscopy) was used to assess the Fn adsorption/activity on surfaces and bacterial cell membranes by looking at molecular scale events. A correlation between molecular scale Fn adsorption and macroscale bacterial adhesion was observed, with an increased numbers of Fn-receptor recognition events measured on cell surfaces as compared to Fg-receptor recognition events, suggesting Fn is an important protein in bacterial adhesion. Monoclonal antibodies recognizing either the carboxyl-terminus or amino-terminus of Fn were coupled to AFM probes and used to assess the orientation of Fn adsorbed on a surface, with an increased amount of Fn carboxyl-terminus availability corresponding to higher bacterial adhesion. Interactions between bacteria and platelets were demonstrated with fluorescence and AFM imaging on the polyurethane surfaces, with albumin inhibiting bacteria-platelet interaction and platelet activation, and both Fg and Fn promoting adhesion of bacteria to platelets and apparent platelet activation, resulting in bacteria/platelet aggregation.