2006-10-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/686232摘要：非線性光學顯微術近年來成為材料及生命科學研究的重要工具，但對於非線性轉換效應是在分子的何處經何種機制產生尚未完全瞭解。纖維狀蛋白是人體內含量最豐富的蛋白種類，其中有數種已知具有甚佳二階非線性光學效應，但對於其特性的基礎研究卻非常缺乏。本研究即著重於比較不同種類纖維狀蛋白的非線性光學特性，並希望運用光學方式釐清光與蛋白質的非線性光學交互作用之物理機制，更對分子構成纖維束的介觀組織結構作一番探索。 本計畫將針對膠原蛋白第一、二型、肌凝蛋白、及微管蛋白進行二階非線性光學特性量測與分析。主要朝三個重點進行：一是量測非線性光學信號強度及極化方向和激發光極化方向的關係；二是比較不同纖維蛋白中非線性光學信號沿光軸向前和向後傳播的強度差異；三則是改變激發波長，使光波長和纖維內部結構尺寸接近而產生共振，進而探討蛋白質纖維的介觀尺寸組成。為了達成這些目的，我們將架設世界上第一套可用波長範圍達200～2000奈米的非線性光學掃瞄顯微系統，這會是科技上的一大突破。此外，對纖維蛋白非線性效應的瞭解增加，不但能對非線性光學應用在生命科技上提供更良好的基礎，更或能拓展其應用範圍，因此是重要的導向型基礎研究。 <br> Abstract: Fibrous protein is the most abundant protein in vertebrates. It has been shown that strong optical nonlinear interactions exhibit on several kinds of fibrous protein, such as collagen, tubulin, and myosin, etc. In recent years, these laser-protein nonlinear interactions attract lots of attentions in biomedical research field through the development of nonlinear scanning microscopies due to their intrinsic sectioning ability and noninvasiveness. Combined with near-infrared excitation sources, their deep-penetration ability makes these imaging modalities suitable for tissue characterization. From previous studies, the polarization behavior of second harmonic generation (SHG) from a collagen fiber is found to be drastically different from that of a muscle fiber, though both are made of fibrous protein with a similar cylindrical symmetry arrangement. Moreover, strong backward SHG can be observed from a collagen fiber while backward SHG from a muscle fiber is diminishing. To understand the physical mechanism underlying is of fundamental importance toward further comprehension about the origin of nonlinear interaction inside them and the molecular structure of these fibrous proteins. The research will put emphasis on the second order nonlinear properties of fibrous proteins, which are known to exhibit strong SHG interactions. The nonlinear interactions will be characterized based on three aspects: 1. The dependency of SHG intensity and polarization on excitation polarization. 2. The ratio of forward/backward SHG from different protein fibers. 3. The resonant behavior when changing excitation wavelengths, to probe the mesoscopic assembly of fibrous protein. To get full understanding of the wavelength dependency of optical nonlinearities in fibrous proteins, an ultra-broadband tunable modelocked laser source covering visible to near-infrared regime (400 ~ 2000-nm) will be developed. It is then vital to construct a scanning microscope system allowing high transmission all the way through ultraviolet to near-infrared. With such a novel nonlinear scanning microscope, various kind of fibrous protein can be characterized. It should be noted that besides several proteins known to exhibit strong nonlinear interaction with light, lots of natural fibrous proteins have not been examined yet, providing a long-term aim for the project.二倍頻膠原蛋白肌凝蛋白微管蛋白掃瞄顯微系統非線性光學頻譜second harmonic generationscanning microscopynonlinear optical spectroscopycollagenmyosintubulin