Microfabricated Solution Chamber for High Resolution Diffracted X-Ray Tracking Method to Observe Ion-Channel Gating Motion

The Diffracted X-ray Tracking (DXT) method enables capturing the motion of ion-channel proteins upon gating by tracking a diffraction spot from a gold nanocrystal. However, high background noise from the conventional observation chamber prevented the clear detection of diffraction spots. In order to reduce the background noise, we propose a novel solution chamber comprising two microfabricated silicon nitride (SiN) membranes. A reduction in background noise as well as trajectories of diffraction spots were observed with this chamber. Furthermore, the gating dynamics of KcsA potassium ion channel occurring in response to acidic pH was successfully measured.