| 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: | J. Knezevic, Technische Universität München, Germany |
| Authors: | J. Knezevic, Technische Universität München, Germany W. Kaiser, Technische Universität München, Germany E. Pringsheim, Technische Universität München, Germany G. Abstreiter, Technische Universität München, Germany U. Rant, Technische Universität München, Germany |
| Correspondent: | Click to Email |
In the recent past, switchable DNA layers have been established as promising candidates for biosensors.1 Here, the efficiency and dynamics of the electrically induced conformation-switching of surface tethered DNA molecules are used as the sensing parameters. The detection of DNA and proteins (antibodies and antibody fragments) has been demonstrated. Moreover, the size of the captured protein targets could be determined from the switching dynamics on-chip. However, the influence of the proteins’ charge remained unclear in these experiments. Here we report on DNA-switching bio-sensing experiments, where the influence of the protein charge was investigated on the basis of the avidin/ streptavidin/ neutravidin-model system. The modulation amplitude of the switching DNA layer was probed electro-optically at low frequencies of the driving electrical signal. The switching kinetics of the tethered molecules were analyzed by frequency resolved measurements. In addition, the double layer charging process was evaluated by impedance measurements. The proteins’ charge was varied on-chip by altering the solution pH value. In complementary measurements, the target proteins were characterized regarding their charge and size by dynamic-light scattering. The correlation between the protein charge and size and the low-frequency switching behavior is evaluated. Further, the influence of the protein charge and size on the switching dynamics is described. The results are discussed within the framework of classical electrostatic screening models. Finally, we elucidate the possibility to employ switchable DNA layers for the charge-sensitive detection and characterization of proteins, as well as biomolecules in general.
1Rant et al., PNAS 2007, vol. 104, pp. 17364-17369.