Protein adhesion, polymer surfaces

Tamada Y, Ikada Y (1993) Effect of preadsorbed proteins on cell adhesion to polymer surfaces. J Colloid Interface Sci 155 334-339... 

Partial results of the calculation are cited in Table 2, which shows that the work of adhesion is expressed as a bell-shape curve. In other words, the maximal adsorption of protein takes place on polymer surface having intermediate hydrophilicity. Ikada et al. confirmed this by the results of BSA adsorption on 8 polymer surfaces [12], and also by those of albumin and fibronectin adsorption on 13 polymer surfaces [14]. L-Cell attachment also showed a bell-shape profile [15],... 

Random polypeptides have traditionally been synthesized by copolymerization of amino acid NCAs. Methods for the synthesis and application of random copolymers have been extensively reviewed (e.g., ref1221), and thus only a single example is given here. A second class of random polypeptides includes organized polymeric assemblies that incorporate bioactive sequences and/or structures. Such polymers have been developed for modulation of protein-ligand interactions/231 protein adsorption to surfaces/241 and cell adhesion/25-281 Several examples for the synthesis of these polymeric assemblies are provided below. 

There are several recent examples of the switching of nonspecific protein binding on polymer surfaces by application of an external stimulus. Alexander and coworkers demonstrated that protein adhesion can be controlled on PNIPAM surface brushes [14, 181]. For instance, it was reported that the adsorption of FITC-labeled bovine serum albumin (FITC-BSA) on PNIPAM/hexadecanethiol micropatterned surfaces could be tuned by LCST. However, this effect was found to be less pronounced after prolonged incubation times or repeated heating/cooling cycles. The authors suggested that this behavior could be due to unspecific PNIPAM-protein interactions [14],... 

Keywords protein adsorption cell adhesion polymer brush surface modification biofouling PEO a-chymotrypsin IgG... 

It has been found that the polymer surface having appropriately grafted nonionic, water-soluble polymer chains minimizes protein adsorption and cell adhesion. It should be noted that such minimum protein adsorption has been well known for a long time for hydrogels used for protein analysis such as polyacrylamine (PAAm) gel for electrophoresis, sephadex for protein gel filtration, and soft agar for cell culture. It is likely that the surface structure of these hydrogels resembles that of the grafted surface described above. 

Our studies (19) indicated that proteins were readily adsorbed from aqueous solution onto hydrophobic polymer surfaces with Langmuir type adsorption and that the rate of adsorption toward a plateau surface concentration depends on the polymer nature. In the study of competitive adsorption from a protein mixture solution (20), fibrinogen and y-globulin adsorb onto FEP very rapidly compared with PEUU and SR. Therefore, the FEP surface in contact with blood has more acceptor sites for platelet adhesion than does the PEUU or SR surface. 

Polymer surface modifications are omnipresent in applications where the surface properties of materials with favorable bulk properties are insufficient. By altering the surface characteristics using physical or chemical modification the desired surface properties may be achieved. Such treatments are required e.g. to enhance printability of films, the adhesion of paints, metal or other coatings, biocompatibility, protein resistances/reduced biofouling, etc. The diverse approaches met in practice include, among others, wet chemical and gas phase chemistry, plasma or corona, UV/ozone and flame treatments. In most cases surface chemical modification reactions take place that alter the surface energy in a desired way. For example,... 

Other materials have also been studied for their ability to reduce protein adsorption onto surfaces. Because many cell membranes are based on phospholipids, polymers containing phospholipid-type head groups have been utilized for this purpose. Poly(2-methacroylethyl phosphoryl choline) could be plasma deposited onto silicone rubber and the adhesion of albumin reduced by factors of up to 80 (Fig. 

These studies indicate that heparin directly affixed to a surface does not provide optimal, solution-like, anticoagulant behavior. The immobilization of heparin directly to the polymer surface resulted in alterations of the surface properties relative to control surfaces, which greatly influenced the plasma protein adsorption characteristics, a controlling factor in platelet adhesion and overall blood compatibility (12). 

Recent experiments indicate that polymers that contain a balance of hydrophobic (nonpolar) and hydrophilic (polar) chemical groups show minimal protein adsorption and cell adhesion (6). With the intent of rationally designing a contact lens material that would minimize protein adsorption, the adsorption of lysozyme, albumin, and immunoglobulin G (IgG) to a series of hydrophobic and hydrophilic polymers and copolymers was measured. The polymers ranged from 100% poly(methyl methacrylate) (PMMA) to 100% poly(2-hydroxyethyl methacrylate) (PHEMA). Adsorption varied significantly for each protein, as did the elutability of the proteins from the surfaces. 

The microscopic events that eventually lead to breakdown and degradation of implanted polyurethanes have been studied. Following implantation, the polymer surface becomes coated with a layer of protein, which enhances the adhesion of macrophages. The activated macrophages release oxidative factors, such as peroxide and superoxide anion, which accelerate chemical degradation of the polymer. The complement protein C3bi appears to be critical in the adhesion and activation of phagocytic cells [50]. 

Several authors have reported that protein adsorption is a maximum on hydrophobic substrates whereas others claim that it is more pronounced on hydrophilic surfaces (15=12). In an attempt to clarify the situation and to elucidate the fundamental mechanisms involved in bioadhesion we have examined the adhesion of various biological cells to a number of polymer surfaces (28-33). The... 

When each of the acrylate or methacrylate polymers was preincubated with whole plasma, the platelet reactivity of the surfaces upon subsequent exposure to whole blood decreased significantly (Fig. 3). On the other hand, with many other polymers this effect of plasma was not seen. Of 20 varieties of segmented polyurethanes examined, none showed this behavior (22), and platelet adhesion to polystyrene was also unaffected by plasma pretreatment ( ). The phenomenon of plasma-induced passivation of methacrylate and acrylate polymers presumably involves selective adsorption of specific plasma proteins by the surfaces and/or a particular alteration of the adsorbed protein once bound. 

One possible objection to the comparison of protein adsorption on flat surfaces with platelet adhesion and activation in polymer-coated bead columns is raised by the work of Vroman et al. (28) who showed that protein adsorption onto surfaces from plasma in narrow... 

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