title: Conformational changes of calmodulin on calcium and Peptide binding monitored by film bulk acoustic resonators.
abstract: Film bulk acoustic resonators (FBAR) are mass sensitive, label-free biosensors that allow monitoring of the interaction between biomolecules. In this paper we use the FBAR to measure the binding of calcium and the CaMKII peptide to calmodulin. Because the mass of the calcium is too small to be detected, the conformational change caused by the binding process is measured by monitoring the resonant frequency and the motional resistance of the FBAR. The resonant frequency is a measure for the amount of mass coupled to the sensor while the motional resistance is influenced by the viscoelastic properties of the adsorbent. The measured frequency shift during the calcium adsorptions was found to be strongly dependent on the surface concentration of the immobilized calmodulin, which indicates that the measured signal is significantly influenced by the amount of water inside the calmodulin layer. By plotting the measured motional resistance against the frequency shift, a mass adsorption can be distinguished from processes involving measurable conformational changes. With this method three serial processes were identified during the peptide binding. The results show that the FBAR is a promising technology for the label-free measurement of conformational changes.
authors.affiliation: Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich Gloriastrasse 35, 8092 Zurich, Switzerland. nirschlm@alumni.ethz.ch.
authors.forename: Martin
authors.initials: M
authors.lastname: Nirschl
authors.affiliation: Novartis Institute of Biomedical Research Basel, CPC/LFP, Novartis Pharma AG, Postfach, Basel CH 4002, Switzerland. johannes.ottl@novartis.com.
authors.forename: Johannes
authors.initials: J
authors.lastname: Ottl
authors.affiliation: Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich Gloriastrasse 35, 8092 Zurich, Switzerland. janos.voros@biomed.ee.ethz.ch.
authors.forename: Janos
authors.initials: J
authors.lastname: Vörös