Rheological characterisation of mixed gels of mucin and alginate

Aqueous mixtures of purified mucin and alginate have been shown to form weak viscoelastic gels under appropriate conditions. These mixed gels of mucin and alginate have been studied by both small deformation and large deformation rheology, and the effects of temperature and ionic strength on small deformation rheology have been investigated. The gels were rheologically reversible, flowing as the shear stress was increased and recovering their solid dominant properties as the shear stress decreased, and thermally stable showing little change in small deformation rheology in the range 10–60 °C. The effect of ionic strength on gel rheology was indicative of the presence of electrostatic interactions within the gel matrix. Based on these investigations, we propose that mixed mucin alginate gels are maintained by both heteropolymeric mucin–alginate interactions and homopolymeric mucin–mucin interactions. The ability of alginate to interact with mucin and promote mucin–mucin interactions may also have relevance to understanding the clinical problems associated with pulmonary infection with the alginate secreting bacterium Pseudomonas aeruginosa in cystic fibrosis patients.