vertical scale of panel (c) is almost four times smaller than those in panels (a) and (b). []{data-label="fdil300"}](Fig3)

Three-steps adsorption
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By increasing the dilution (i.e. reducing $X_P$) all the surface concentrations tends toward the same large-time limit (Fig. \[fdil300\]). Alb concentration reaches a shallow minimum at a time $t^*_{X_P}$ that depends on $X_P$ and approximately corresponds to that of maximum surface concentration of IgG.

This time $t^*_{X_P}$ coincides, within our numerical precision, also with the beginning of a “linear” regime, i.e. a regime of constant adsorption rate, for the Fib. This linear regime represent a second step in the Fib adsorption and precedes a third step during which $C^S_F$ saturates. This three-steps kinetics has been experimentally observed, and numerically reproduced, in single protein adsorptions on thin SiO$_2$ layers, both hydrophilic or with an additional hydrophobic monolayer, at room temperature and at 37.5 $^\circ$C [@Quinn2008; @Bellion2008]. The authors of those works interpreted this behavior as a consequence of protein diffusion at the surface and of the occurrence of conformational changes. However, they did not study the case with competitive adsorption.

Here, instead, we observe that the regime of constant Fib adsorption rate coincides with the IgG desorption and the slow 