@article {17593, title = {Studies on the Interactions between Bovine β-lactoglobulin and Chitosan at the Solid{\textendash}Liquid Interface}, journal = {Electrochimica Acta}, volume = {55}, year = {2010}, month = {2010-12-01 00:00:00}, pages = {8779-8790}, publisher = {Elsevier}, abstract = {

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{\textendash}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{\textquoteright}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{\textendash}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.

}, keywords = {AFM, Bovine β-Lactoglobulin, Chitosan, CV, EIS, Electron transfer, Gold, LbL deposition, polyelectrolytes, Probes, protein adsorption, QCM-D, self-assembly}, doi = {10.1016/j.electacta.2010.08.012}, url = {http://www.sciencedirect.com/science/article/pii/S0013468610010674}, author = {Campi{\~n}a, J. M. and Souza, H. K. S. and Borges, J. and Martins, A. and Gon{\c c}alves, M. P. and Silva, F.} }