X-Ray Diffraction Imaging of Biological Cells by Masayoshi Nakasako

Author:Masayoshi Nakasako
Language: eng
Format: epub, pdf
Publisher: Springer Japan, Tokyo

5.3.2 Humidity-Controlled System for Specimen Preparation

5.3.2.1 Devices Composing the System

The specimen preparation procedure for XDI experiments is conducted in three steps. A droplet of a suspension of specimen particles is set onto a thin silicon nitride membrane with a PLL layer. After the adsorption of particles onto the membrane, excess amounts of buffer solution are removed by blotting and evaporation under low RH conditions, in order to reduce the background scattering and absorption in XDI experiment. Finally, the membrane adsorbing particles are flash-cooled by a cryogen .

An RH -controlling system suitable for performing a three-step procedure was developed [7, 8] (Fig. 5.5). The system is composed of a moist-air generator equipped with an RH -controlling chamber, a transfer tube with a heating device, a microinjector mounted on a motor-controlled micromanipulator, and a specimen preparation chamber set on the sample stage of an optical microscope. The temperature and RH in the chamber are monitored using humidity sensors.

Fig. 5.5a Photograph of the specimen preparation chamber. b Example of the performance of the system to control the volume of a droplet (50 fL) from a buffer solution by changing the RH . When the RH of moist air is ramped down from 92.5 to 83%rh, the volume of a droplet became the half of the initial. When the RH of moist air is increased, the volume change is reversed and returns to its initial. The volume changes little under a constant RH . c Photograph of a specimen preparation system composed of a moist-air generator , a specimen preparation chamber mounted on a light microscope, and a liquid-ethane freezing device. Panels (a) and (b) are reused with modification from [7] with permission from AIP publishing. Panel (c) is reused with modification from [8] with permission from AIP publishing

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