Table 2.

Properties of protein films over polystyrene (PS) surfaces obtained at the end of the isotherms or by direct adsorption of protein solutions (1-mg/mL concentration, T = 298 K, pH 6 for BSA and $\beta$-lactoglobulin and pH 7 for $\beta$-casein). The adsorbed mass $m_f$ is obtained by QCM-D, and the thickness $h_{\mathrm{AFM}}$ is obtained by AFM in air (see the height profiles in Figure 5). The area per protein is computed from $m_f$ of the direct adsorption using Equation (1).

Protein Film	Isotherm ${\mathit{m}}_{\mathit{f}}$ (mg/m2)	Direct ads ${\mathit{m}}_{\mathit{f}}$ (mg/m2)	${\mathit{a}}_{\mathit{p}}$ (nm2)	${\mathit{h}}_{\mathbf{AFM}}$ (nm)
PS-$\beta$-lg	1.41 ± 0.03	2.1 ± 0.2	14.4	∼3
PS-BSA	1.88 ± 0.08	3.8 ± 0.4	29	∼5
PS-$\beta$-cas	3.7 ± 0.1	6.1 ± 0.7	–	∼7