Mucins are macromolecular proteoglycans that are found in tear fluid,
saliva and other lubricating secretions. These molecules are known to adsorb
to a variety of surfaces, particularly to hydrophobic surfaces, but the
adsorption process is not well studied. Mucin coated surfaces give rise to
a significantly reduced adsorption of proteins, bacteria, and cells, so
an increased knowledge about the adsorption process is of large interest.
In this collaboration project between the Centre for Surface Biotechnology
at Uppsala University (Prof. K. Caldwell), Dept. of Chemistry at KTH, and
the Dept. of Applied Physics at Chalmers/GU, the adsorption behaviour of
mucin from bovine saliva onto hydrophobic model surfaces is studied. The
adsorption process is characterized in terms of its various phases, surface
arrangements at steady state and competitive adsorption with smaller proteins
that are also present in saliva.
The complex starting material (commercial bovine submaxillary mucin) has
been fractionated to yield a well-defined fraction with a molecular weight
of 2x106 Dalton (by static light scattering). The adsorption
behaviour of this fraction on hydrophobic model surfaces (polystyrene) has
been studied using QCM-D. Given that ultra-high molecular weight materials
of the mucin type are present in a multitude of conformations, reflecting
the concentration of the polymer, much attention has been focused on finding
conditions with reproducible adsorption behaviour. Such conditions have now
been identified, and an aliquot of “standard mucin” has just been forwarded
to KTH (Dr. Eva Blomberg, YKI) for adsorption studies by means of AFM and
surface force apparatus. It is anticipated that the final result of our
joint program will be at hand on June 1, 2004.
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