The interfacial organization of mucin (glycoprotein) in the presence of chromium(111) complexes has been assessed from the surface pressure-molecular area (pi-A) isotherms in Langmuir films at air-water interface and the surface energy of their LB films through contact angle measurements. At pH 7.0, the electrostatic interaction of [Cr(en)(3)]Cl-3 with mucin was found to bring about changes in the average surface area from 3.26 to 1.47 nm(2); suggesting the possible formation of large aggregates of mucin. Adsorption experiments using surface potential measurements reveal that [Cr(en)(3)]Cl-3 binds at a much faster rate to the available binding sites in mucin when compared to [Cr(salen)(H2O)(2)](ClO4) which binds coordinatively to mucin. (C) 2002 Elsevier Science B.V. All rights reserved.