title: Surface rearrangement of adsorbed EGCG-mucin complexes on hydrophilic surfaces.
abstract: The kinetic adsorption-desorption behaviour of porcine gastric mucin in the presence of physiologically relevant concentrations of the polyphenol epigallocatechin gallate (EGCG) was investigated using high-resolution kinetic optical waveguide lightmode spectroscopy (OWLS) and atomic force microscopy (AFM). Comparison with dynamic light scattering results from EGCG-mucin mixtures indicates that discrete particles are formed whose size increases with increasing EGCG:mucin ratio. These particles are deduced to be the adsorbing entities, which fuse on the surface to form complex surface layers. At low molar EGCG:mucin ratios (<∼1000), aggregates fuse on the surface to form a monolayer similar to one of pure mucin. With increasing EGCG concentration, the surface assembly of aggregates becomes consistent with their rearrangement and spreading in the shape of a spherical segment. At the highest molar ratios investigated (>12,000) the particles begin to destabilize. The presence of EGCG leads to birefringence hysteresis during adsorption-desorption, indicating structural rearrangement, even at molar ratios ∼1000. The intensification of the phenomenon with increasing EGCG:mucin ratio mimics what was previously observed with the increase of mucin concentration in an EGCG-free system.
authors.affiliation: Department of Materials, Cranfield University, Bedfordshire, MK43 0AL, UK; Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK.
authors.forename: J
authors.initials: J
authors.lastname: McColl
authors.affiliation: Department of Materials, Cranfield University, Bedfordshire, MK43 0AL, UK; Nanobiosensorics Laboratory, MTA-EK-MFA, Konkoly-Thege Miklós út 29-33, 1121 Budapest, Hungary.
authors.forename: R
authors.initials: R
authors.lastname: Horvath
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, The University of Queensland, Brisbane, QLD, 4072, Australia; Unilever Discover, Unilever, Colworth Science Park, Bedfordshire, MK44 1LQ, UK. Electronic address: gleb.yakubov@uq.edu.au.
authors.forename: G E
authors.initials: GE
authors.lastname: Yakubov
authors.affiliation: Department of Materials, Cranfield University, Bedfordshire, MK43 0AL, UK; Clore Laboratory, University of Buckingham, MK18 1EG, UK. Electronic address: jeremy.ramsden@buckingham.ac.uk.
authors.forename: J J
authors.initials: JJ
authors.lastname: Ramsden
mesh_terms: D000327:Adsorption; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D005752:Gastric Mucins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D013499:Surface Properties
chemical_list: D005752:Gastric Mucins; D002392:Catechin; C045651:epigallocatechin gallate
keywords: Clustering; Glycoprotein; Hysteresis; Kinetics; OWLS; Polyphenol