Potential use of mucins as biomaterial coatings. I. Fractionation, characterization, and model adsorption of bovine, porcine, and human mucins.

Previously, we presented evidence that mucins have potential as biomaterial coatings. Here, we reveal substantial batch-to-batch variations for a frequently used commercial bovine salivary mucin preparation (BSM) and stress the importance of standardizing mucins intended for comparative purposes. "Mild" fractionation strategies, aiming at preserving natural mucin functions, were used to prepare two more defined BSM fractions as well as three mucin fractions from porcine gastric (PGM) and human salivary (MG1) sources. While the BSM and PGM were highly purified and mainly adopted random coil conformations in solution, the MG1 contained mucin-bound components (1.6 wt% albumin) and appeared compact. Average molar masses and root-mean-square radii for the predominant BSM, PGM, and MG1 species spanned 0.8-4.2 MDa and 46-86 nm, respectively. An ellipsometric evaluation, using hydrophilic and hydrophobic silica, showed the mucin adsorption to be slow and related to mucin charge, size, conformation, and compositional complexity. The mass uptakes on hydrophobic silica averaged 2.6, 2.6, and 5.0 mg/m(2), for BSM, PGM, and MG1, respectively. Finally, we find that stable mucin coatings can be formed on polymers of different wettability. The reported mucin preparations serve as platforms for a series of studies on the biocompatibility of mucin coatings.