| AVS 55th International Symposium & Exhibition | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session with Focus on Engineered Bio-Interfaces and Sensors |
| Presenter: | E. Briand, Chalmers University of Technology, Sweden |
| Authors: | E. Briand, Chalmers University of Technology, Sweden F. Höök, Chalmers University of Technology, Sweden B. Kasemo, Chalmers University of Technology, Sweden S. Petronis, Chalmers University of Technology, Sweden |
| Correspondent: | Click to Email |
The added value of using synchronized Electrochemical Impedance Spectroscopy (EIS) and Quartz Crystal Microbalance with Dissipation (QCM-D) monitoring is that phenomena and properties, hidden for one of the techniques, may be dynamically resolved by the other one. EIS provides information about the electrical properties of the studied system, while QCM-D provides information about adsorbed mass variations and viscoelastic properties of the adlayer. We have here applied these combined techniques to study (i) supported lipid bilayer formation and (ii) subsequent pore formation using gramicidin D. The results demonstrate how these techniques in combination provide new insights about this and similar bio-adlayer systems. (i) The signatures, produced by the two techniques, of lipid bilayer formation on SiO2 from nanosized POPC liposomes, are quite different. The well established QCM-D signature tells that the initial kinetic phase consists of intact liposome adsorption, followed by vesicle rupture and fusion of lipid bilayer patches to a coherent bilayer. In contrast, EIS does not show any change in impedance until slightly before the critical liposome coverage is reached, where rupture and bilayer formation begins. Furthermore, at the end of the process, where the QCM-D ∆f and ∆D signals have reached stable bilayer values, the electrical resistance still varies for several minutes, indicating a rearrangement/annealing process and/or additional minor addition of lipids. The absolute value of the bilayer resistance was found to significantly improve when cations were present in the buffer. (ii) Using a high resistance bilayer as the starting point, the insertion of gramicidin D was followed by QCM-D and EIS. By simultaneously recording EIS signals and changes in the viscoelastic properties (QCM-D) of the bilayer, at different GrD concentrations it was possible to identify the range of concentrations suitable for combined studies of the peptide activity and pore formation.