Studies on the Interactions between Bovine β-Lactoglobulin and Chitosan at the Solid-Liquid Interface

• Type: Article in International Scientific Journal
• Date: 2010

Authors

José M. Campiña (Author) Other; Hileia K. S. Souza (Author) FEUP; João Borges (Author) Other; Ana Martins (Author) Other; Maria Pilar Gonçalves (Author) FEUP; Fernando Silva (Author) Other

Journal

Title: Electrochimica Acta

Vol. 55 No. 28

Pages: 8779-8790

ISSN: 0013-4686

Publisher: Elsevier

Indexing

ISI Web of Science

Scopus

Scientific classification

FOS: Engineering and technology > Other engineering and technologies

Other information

DOI: 10.1016/j.electacta.2010.08.012

Abstract (EN): Chitosan ultrathin films have been formed on polycrystalline Au substrates using the LbL technique with the purpose of studying its interaction with bovine β-lactoglobulin (β-LG) at the solid-liquid interface. The immobilization of chitosan was followed by Quartz Crystal Microbalance with energy dissipation (QCM-D), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The behavior of the chitosan films in the presence of β-LG solutions with different bulk concentrations ([β-LG]), ionic strength (I), and pH has been investigated using the same techniques plus Atomic Force Microscopy (AFM). The results showed that for pHs lower than protein's pI, weak intermolecular forces (H bonding, Van der Waals, hydrophobic, etc.) are established between β-LG and chitosan (especially close to the pI) leading to low coverage nonspecific adsorption. On the contrary when pH > pI, strong ionic bonding through attractive electrostatic interactions lead to high coverage adsorbed phases composed of large β-LG aggregates. The adsorption process was shown to consist of a relatively fast step (in which these interactions are predominant) which is followed, once the β-LG monolayer is exceeded, by the slow formation of thicker and increasingly viscoelastic films through β-LG self-aggregation. QCM-D and AFM experiments unveiled the role of [β-LG] and I on the formation of these aggregates. The adsorption isotherm built from impedance data in the medium-low [β-LG] range (0.001-0.3 mg mL-1), showed good fitting to the Langmuir model confirming that the formation of one β-LG monolayer is achieved in this concentration range.

Language: English

Type (Professor's evaluation): Scientific