Abstract
The existence and functions are essential for life. Morphology and size are varied from different proteins. Many kinds of well-studied proteins are tens of nanometers in diameter, however, optical microscope, due to the limitation of wavelength of light, can offer only 300 nm in resolution and may not be suitable for observing such phenomenon as Protein-based molecular motor, Membrane-embedded ion channels and transport proteins and Photosynthesis and so forth. Thus, Electron microscope are required for observing proteins. Since proteins are composed of light elements such as C, H, O, S, N, which are not able to have intensive contrast as Gold nanoparticles do, frozen and staining treatments are needed. In this thesis, we use Si3N4 thin film as windows of our devices (Wet-cell) to observe a known protein with characteristic structure named GroEL. In fact, Si3N4 thin film will result in more inelastic scattered electrons than commercially used carbon film. To enhance the performance, we used HF to thin down Si3N4 membrane and acquired similar quality as acquired on carbon film. Furthermore, liquid samples can be sealed by Si3N4 membrane in order to In-situ observe the samples. Yet, we acquired some liquid state images which are not as clear as previous dry state images. Therefore, we plan to change background substrates to enhance images contrast and explore new materials for Wet-cell as well. Now we use Silicon as substrate and are able to visualize 1.8 nm Gold nanoparticle pairs labelled on the V-PPase. In the future, we hope to use software analysis to enhance contrast and find suitable materials to visualize protein images without artificial treatments.