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    In situ investigations of Fe3+ induced complexation of adsorbed Mefp-1 protein film on iron substrate

    Year: 2013

    Journal: Journal of Colloid and Interface Science Volume 404, 15 August 2013, Pages 62–71, 20130628

    Authors: Fan Zhang a, Majid Sababi a, Tore Brinck b, Dan Persson c, Jinshan Pan a, Per M. Claesson a d

    Last authors: Per M. Claesson

    Organizations: a KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden b KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Applied Physical Chemistry, Teknikringen 36, SE-100 44 Stockholm, Sweden c Swerea KIMAB, P.O. Box 704, SE-7164 07 Kista, Sweden d SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm, Sweden

    Country: Sverige, Sweden

    A range of in situ analytical techniques and theoretical calculations were applied to gain insights into the formation and properties of the Mefp-1 film on iron substrate, as well as the protein complexation with Fe3+ ions. Adsorption kinetics of Mefp-1 and the complexation were investigated using QCM-D. The results suggest an initially fast adsorption, with the molecules oriented preferentially parallel to the surface, followed by a structural change within the film leading to molecules extending toward solution. Exposure to a diluted FeCl3 solution results in enhanced complexation within the adsorbed protein film, leading to water removal and film compaction. In situ Peak Force Tapping AFM was employed for determining morphology and nano-mechanical properties of the surface layer. The results, in agreement with the QCM-D observations, demonstrate that addition of Fe3+ induces a transition from an extended and soft protein layer to a denser and stiffer one. Further, in situ ATR-FTIR and Confocal Raman Micro-spectroscopy (CRM) techniques were utilized to monitor compositional/structural changes in the surface layer due to addition of Fe3+ ions. The spectroscopic analyses assisted by DFT calculations provide evidence for formation of tri-Fe3+/catechol complexes in the surface film, which is enhanced by Fe3+ addition.