Two Models of the Protein-Adsorption Processes

More than 10 years ago, Ikada et al. evaluated the free energy (ylw) of the interface between polymer and water, and the work of adhesion (W12,w) in water of bovine serum albumin (BSA) to the polymer surface [12]. According to a well-known concept of surface chemistry, Ikada derived the following equations. 

The values of W12,w were calculated by inserting values obtained for Yiw, Yiw, Y2w and yp2v, in Eq. (2.5). 

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], 

The bell-shape-profile concept for protein adsorption may be a useful guideline for researchers when they consider the adsorptive behavior of proteins on polymers with different degrees of hydrophilicity. As will be discussed in later Sect. (2.3), when material surfaces carry ionic groups, the contribution from 

Peppas et al. [16] presented a new method for calculating protein adsorption on polymeric surfaces. In their model, protein adsorption is regarded as an equilibrium reaction, which takes place on the polymer surface in competition with the adsorption of water. 

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