Enhanced interaction with membrane surface groups

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). 

Although the presence of buffering moieties on membrane surfaces reduces the apparent diffusion coefficient of a proton, it can enhance the probability that protons in the bulk phase will interact with groups on a membrane surface. This feature is demonstrated by the experiments presented in Figure 3. The measured parameter in these experiments was the protonation of a pH indicator adsorbed to the surface of a micelle made of uncharged detergent (Brij 58). The protons were released in the bulk from a hydrophilic proton emitter, 2-naphthol-3,6-disulfonate. The protons released in the bulk react by a diffusion-controlled reaction with the micelle-bound indicator and lead to a fast protonation phase. The perturbation then relaxes,... 

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