Selective protein adsorption

St and divinylbenzene (DVB) were polymerized in a dispersion of acryl-amide-methacrylic acid-methylenebisacrylamide terpolymer particles (25). Fine polystyrene particles were formed in/on each seed terpolymer particle. The former was smaller by about one-twentieth than the latter. The distribution of polystyrene particles depended on the cross-link density. Different amounts of St and DVB were charged in the seeded polymerization, and the resulting composite particles were used for protein adsorption measurement to assess the hydrophobicity of the particle surface. The adsorbed amount was almost proportional to the amount of St and DVB charged. In contrast, cells were less stimulated by the 5% St-containing particle than by the 0% St-containing one, that is, the seed particle. This phenomenon is attributed to selective protein adsorption on the 5% St-containing particle (26). 

In this section, we will highlight the use of the grafting technique for designing polymeric biomaterial surfaces that exhibit non-fouling property, selective protein adsorption, enhanced tissue adhesion, and minimum frictional damage to mucosa membranes. 

Selection of polymer pairs for surface patterns that would group proteins. AFM topography (a) and phase oontrast (o) images of spin-cast film blends PS/PMMA (a) and PS/PEO (c) and fluorescence micrographs (b,d) and intensity scans (b, d ) of adsorbed lectins lentil lectin LcH (b,b ) and concanavalin A ConA (d,d ). Highly selective protein adsorption enabling fabrication of test plates for protein microarrays (e) is concluded only for the PS/PEO pair. 

Zemla J, Lekka M, Raczkowska J, Bemasik A, Rysz J, Budkowski A. Selective protein adsorption on polymer patterns formed by self-organization and soft lithography. Biomacromolecules 2009 10 2101-9. 

The formulator must be aware of the potential for binding when filtering protein solutions. Because of the cost of most protein materials, a membrane should be used that minimizes protein adsorption to the membrane surface. Typical filter media that minimize this binding include hydrophilic polyvinylidene difluoride and hydroxyl-modified hydrophilic polyamide membranes [17a]. Filter suppliers will evaluate the compatibility of the drug product with their membrane media and also validate bacterial retention of the selected membrane. 

Recent reports describe the use of various porous carbon materials for protein adsorption. For example, Hyeon and coworkers summarized the recent development of porous carbon materials in their review [163], where the successful use of mesoporous carbons as adsorbents for bulky pollutants, as electrodes for supercapacitors and fuel cells, and as hosts for protein immobilization are described. Gogotsi and coworkers synthesized novel mesoporous carbon materials using ternary MAX-phase carbides that can be optimized for efficient adsorption of large inflammatory proteins [164]. The synthesized carbons possess tunable pore size with a large volume of slit-shaped mesopores. They demonstrated that not only micropores (0.4—2 nm) but also mesopores (2-50 nm) can be tuned in a controlled way by extraction of metals from carbides, providing a mechanism for the optimization of adsorption systems for selective adsorption of a large variety of biomolecules. Furthermore, Vinu and coworkers have successfully developed the synthesis of... 

In contrast to other analytical methods, ion-selective electrodes respond to an ion activity, not concentration, which makes them especially attractive for clinical applications as health disorders are usually correlated to ion activity. While most ISEs are used in vitro, the possibility to perform measurements in vivo and continuously with implanted sensors could arm a physician with a valuable diagnostic tool. In-vivo detection is still a challenge, as sensors must meet two strict requirements first, minimally perturb the in-vivo environment, which could be problematic due to injuries and inflammation often created by an implanted sensor and also due to leaching of sensing materials second, the sensor must not be susceptible to this environment, and effects of protein adsorption, cell adhesion, and extraction of lipophilic species on a sensor response must be diminished [13], Nevertheless, direct electrolyte measurements in situ in rabbit muscles and in a porcine beating heart were successfully performed with microfabricated sensor arrays [18],... 

As a technique for selective surface illumination at liquid/solid interfaces, TIRF was first introduced by Hirschfeld(1) in 1965. Other important early applications were pioneered by Harrick and Loeb(2) in 1973 for detecting fluorescence from a surface coated with dansyl-labeled bovine serum allbumin, by Kronick and Little(3) in 1975 for measuring the equilibrium constant between soluble fluorescent-labeled antibodies and surface-immobilized antigens, and by Watkins and Robertson(4) in 1977 for measuring kinetics of protein adsorption following a concentration jump. Previous rcvicws(5 7) contain additional references to some important early work. Section 7.5 presents a literature review of recent work. 

The low selectivity and adsorption effect of proteins on capillary wall have been noted as disadvantages of the Hummel-Dreyer method in CE (54). 

Discuss with your neighbor how protein adsorption can still be spontaneous (AG < 0), even though some of these processes are endothermic (AH > 0). Look up values for the solid surface energies of the two substrates in Appendix 4 (you may have to select similar materials, but this is sufficient for these purposes). How do these enthalpies compare in magnitude to the respective surface energies ... 

Specific domains of proteins (for example, those mentioned in the section Organic Phase ) adsorbed to biomaterial surfaces interact with select cell membrane receptors (Fig. 8) accessibility of adhesive domains (such as specific amino acid sequences) of select adsorbed proteins may either enhance or inhibit subsequent cell (such as osteoblast) attachment (Schakenraad, 1996). Several studies have provided evidence that properties (such as chemistry, charge, and topography) of biomaterial surfaces dictate select interactions (such as type, concentration, and conformation or bioactivity) of plasma proteins (Sinha and Tuan, 1996 Horbett, 1993 Horbett, 1996 Brunette, 1988 Davies, 1988 Luck et al., 1998 Curtis and Wilkinson, 1997). Albumin has been the protein of choice in protein-adsorption investigations because of availability, low cost (compared to other proteins contained in serum), and, most importantly, well-documented conformation or bioactive structure (Horbett, 1993) recently, however, a number of research groups have started to examine protein (such as fibronectin and vitronectin) interactions with material surfaces that are more pertinent to subsequent cell adhesion (Luck et al., 1998 Degasne et al., 1999 Dalton et al., 1995 Lopes et al., 1999). 

Recent studies have attempted to further elucidate mechanisms of protein adsorption on biomaterial surfaces. For example, Ellingsen (1991) reported that adsorption of calcium on titanium surfaces subsequently enhanced binding of select proteins. In contrast, adsorption of other ions (such as... 

Select proteins that mediate adhesion of specific anchorage-dependent cells (such as osteoblasts, fibroblasts, and endothelial cells) on substrate surfaces have been identified (Underwood and Bennett, 1989 Thomas et al., 1997 Ayad et al, 1994). For example, adsorption of fibronectin and vitronectin on tissue-culture polystryene subsequently enhanced osteoblast, fibroblast, and endothelial cell adhesion (Underwood and Bennett, 1989). More importantly, fibronectin and vitronectin adsorption on borosilicate glass, in a competitive environment, maximized fibroblast and osteoblast adhesion, respectively (Thomas et al., 1997). Ayad et al. (1994) reported that enhanced adsorption of laminin on tissue-culture polystyrene promoted subsequent endothelial cell adhesion. These studies provided evidence that adsorption of specific protein(s) can, subsequently, control select cell adhesion on material surfaces. 

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