Effect of a hydrophobic phospholipid lining of the gastric mucosa in bioadhesion

The role of a model hydrophobic phospholipid simulating lining of the gastric mucosa, as to adhesion of polymers with different surface functional groups and surface hydrophobicities, was evaluated using an in vitro gastric mucus model.

Front-faced fluorescence measurement was used to determine adhesion of fluorescent polystyrene microspheres with different surface functional groups. Contact angle measurements and sticking bubble technique were used to measure relative surface hydrophobicity of the polymers.

Adhesion of fluorescent polystyrene microspheres using front-faced fluorescence measurement revealed the hydrophobic phospholipid lining of the in vitro gastric mucus model did not allow adhesion of microspheres with -COOH and -NH(2) functional groups, whereas it did allow adhesion of microspheres with hydrophobic attributes. In addition, in vitro adhesive force studies using diblock copolymers of polystyrene and polyacrylate showed that the in vitro adhesive force between the hydrophobic phospholipid lining of the in vitro gastric mucus model and the polymer increased when the surface hydrophobicity of the polymer increased.

The hydrophobic phospholipid acts as an adhesion barrier to hydrophilic bioadhesive polymers and polymers with surface functional groups of carboxylic acid and amine. The hydrophobic phospholipid lining of the gastric mucosa should be taken into considerations for screening and designing of a new gastric bioadhesive polymer.