| Abstract
| - Quartz crystal microbalance with dissipation monitoring (QCM-D) has been employed to study theinteractions between (−)-epigallocatechin gallate (EGCG) and bovine serum albumin (BSA) surface.The adsorbed mass, thickness, and viscoelastic properties of EGCG adlayer on BSA surface at variousEGCG concentrations, temperatures, sodium chloride concentrations, and pH values have beendetermined by QCM-D in combination with the Voigt model. The adsorption isotherm of EGCG onBSA surfaces can be better described by the Freundlich model than the Langmuir model, indicatingthat EGCG adsorption on BSA surfaces is dominated by nonspecific hydrophobic interactions, assupported by stronger EGCG adsorption at higher temperature. Shifts in the Fourier transform infraredspectra of the BSA surface with and without EGCG adsorption disclose that hydrogen bonding mightalso be involved in EGCG adsorption on BSA surfaces. The addition of salt and change of pH canalso influence the EGCG adsorption on BSA surfaces. Usually, higher EGCG adsorption leads tohigher values of viscosity and shear elastic modulus of EGCG adlayer, which can be explained bythe aggregation of BSA through EGCG bridges. Compared with EGCG, nongalloylated (+)-catechinshows much lower adsorption capacity on BSA surfaces, suggesting the importance of the galloylgroup in polyphenol/protein interactions. Keywords: (−)-Epigallocatechin gallate; bovine serum albumin; interfacial interaction; mass, viscoelastic properties; hydrophobic interaction; hydrogen bonding; galloyl group
|
