Modelling and measurements of fibrinogen adsorption on positively charged microspheres

Adsorption of fibrinogen on positively charged microspheres was theoretically and experimentally studied. The structure of monolayers and the maximum coverage were determined by applying the experimental measurements at pH=3.5 and 9.7 for NaCl concentration in the range of ${10}^{-3}-0.15$ M. The maximum coverage of fibrinogen on latex particles was precisely determined by the AFM method. Unexpectedly, at pH=3.5, where both fibrinogen molecule and the latex particles were positively charged, the maximum coverage varied between 0.9 mg m${}^{-2}$ and 1.1 mg m${}^{-2}$ for ${10}^{-2}$ and 0.15 M NaCl, respectively. On the other hand, at pH=9.7, the maximum coverage of fibrinogen was larger, varying between 1.8 mg m${}^{-2}$ and 3.4 mg m${}^{-2}$ for ${10}^{-2}$ and 0.15 M NaCl, respectively. The experimental results were quantitatively interpreted by the numerical simulations.