Human palatal saliva: Adsorption behaviour and the role of low-molecular weight proteins

In situ ellipsometry was employed to study adsorption from human palatal saliva (HPalS) in terms of dependence on surface wettability and saliva concentration ( ? 1%). Adsorbed amounts, kinetics, and elutability with buffer and sodium dodecyl sulphate (SDS) were determined. The low-molecular weight protein content of bulk HPalS was also investigated using two-dimensional gel electrophoresis, and this revealed the presence of a large group of proteins < 100 kDa in size. Adsorption to pure (hydrophilic) and methylated (hydrophobized) silica surfaces revealed that the total adsorbed amounts were greater on hydrophobized silica. Below concentrations of 0.5 and 0.25% saliva, adsorption was concentration dependent on hydrophobized and hydrophilic surfaces, respectively. The initial adsorption ( ? 30 min) was faster on hydrophobized surfaces. Addition of SDS removed more material than buffer rinsing on both surfaces. Analysis of the adsorption kinetics indicated that the presence of low-molecular weight proteins plays a role in adsorption from HPalS.