原子力顯微鏡場效應鐵蛋白影像分析

Atomic Force Microscope Field Effect Iron-storage Protein Image Analysis

何如紘(Ju-Hung Ho)

指導教授 ： 王忠茂

國立臺灣師範大學/理學院/化學系/碩士(2010年)

摘要

本論文利用磁性模組（Magnetic mode簡稱M-AFM）與導電模組（Conductive mode簡稱C-AFM）原子力顯微鏡技術，對儲鐵蛋白與其他蛋白質的影像與結構進行分析。實驗結果顯示，儲鐵蛋白的C-AFM影像與其結構極為吻合，顯示C-AFM具有蛋白質結構比對的應用潛力。我們測量儲鐵蛋白的M-AFM影像，發現雖然儲鐵蛋白的結構中存在鐵核，似乎不具有磁性。雖然如此，若對其施加偏壓，則可測得其影像，影像清晰度與偏壓大小成正比。根據數據模擬，該效應可能來自於偏壓可提升導電基材（ITO導電玻璃）或是蛋白質的磁矩（magnetic moment），與Agarwal所提出的理論頗為吻合。
　　本論文也利用偶氮化修飾法修飾類核黃素，如Thionine chloride，製備儲鐵蛋白修飾電極，並藉以探討電子在該蛋白質表面的穿隧行為。實驗結果顯示：儲鐵蛋白經Thionine chloride固定後，其與ITO間的吸附力相當於102個C－C單鍵的鍵能，而電子在其表面的傳遞速率約為自由電子的千分之一至百分之一。

關鍵字

鐵蛋白 ； 導電模組原子力顯微鏡 ； 磁性模組原子力顯微鏡

並列摘要

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.

並列關鍵字

Ferritin ； C-AFM ； M-AFM

參考文獻

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