Atomic Force Microscope Field Effect Iron-storage Protein Image Analysis

• Main Authors: Ju-Hung Ho, 何如紘
• Other Authors: Chong-Mou Wang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/64071807062752029372

碩士 === 國立臺灣師範大學 === 化學系 === 98 === Conductive-mode and magnetic-mode atomic force microscopic techniques (C-AFM and M-AFM) are potential tools for protein image mapping, and iron-storage protein, such as ferritin (FT), is an ideal model for such a study. As FT was subjected to C-AFM analysis, it showed 10 nm for its diameter and five layers, ~20 Å each in segregation, symmetrically distributed around the iron core, matching well with its 3D model. We also conducted M-AFM for structural comparison. Experimental results revealed that FT showed only vague image at lower lift height (~1 nm). Nevertheless, as it was subjected to electric bias, the image was greatly enhanced; the phase shift increased linearly with the amplitude of the applied bias. Noticeably, the resulting image was ~40 nm larger than that from the C-AFM counterpart. We attributed the discrepancy to the long range interaction between the magnetic moments of the probe and the substrate. Despite this, the interaction could in turn promote the phase shift of FT on ITO. We also characterized the electron tunneling in ferritin. The energy barrier for electrons to travel in the protein was about 2 eV, and the speed was 10-3~10-2 the speed of free electrons.