- 學位論文
新型間位胺基取代之類綠螢光蛋白發光團的合成與螢光性質
Synthesis and Fluorescence Properties of New Meta-Amino Substituted GFP Chromophore Analogues
摘要
本實驗室過去發現間位胺基取代類綠螢光蛋白發光團能有效地提高螢光量子產率，例如：m-DMABDI在正己烷中的螢光量子產率高達0.46，並在質子性溶劑中具螢光淬滅的特性，這一類的發光團也被成功的應用至人類乳腺上皮細胞做細胞顯影，在細胞中呈現綠色螢光。 本論文內容指在將m-DMABDI做結構修飾成化合物1-4，利用非共軛 π-π 作用力，希望使其放光能更加紅位移。在結構設計上保留了間位胺基取代效應來提高螢光量子產率，以及在質子、非質子性環境中具有螢光量子產率的高度對比差異。根據Hirayama’s rule，期望能夠藉形成分子內激發錯合體得到放光紅移並高亮度的發光團，並在發光團的部位加上酯基做為m-D1Aa的前驅物；於是我們在m-DMABDI間位的胺基上修飾上苯乙基團 (n = 3)或苯丙基團 (n = 4)，除了希望使放光紅位移之外，並嘗試了解碳鏈長度在這個系統與Hirayama’s rule的關係；另外，嘗試在苯環的對位接上推、拉電子基 (-OMe、-CN)，利用增強或減弱施予體的強度改變發光團的放光波長。目前研究的結果顯示，我們所設計的分子1-4在常溫下觀測不到因分子內激發錯合體形成所造成的紅位移放光，化合物3、4因取代基效應各自藍位移及紅移大約10 nm；而我們發現化合物1在180 K低溫的環境下，螢光放光紅位移了30 nm。
並列摘要
Meta-Amino substituted green fluorescence protein chromophores (GFPc) such as m-DMABDI displays strong fluorescence in non-polar aprotic solvents (e.q., ϕ_f = 0.46 in n-Hex)as a result of the “meta-amino substituent effect” but undergoes fluorescence quenching in protic solvents due to solvent–solute H-bonding interactions. This type of chromophore has been applied in bioimaging, which showed green fluorescence in the hydrophobic regions of human mammary epithelial cells. However, fluorescent dyes with green emission might be interfered by autofluorescence of the biological samples. In order to avoid this problem, developing chromophores of red-shifted emission is necessary. In this thesis, we modified the structure of m-DMABDI to four compounds 1-4 to introduce non-covalent π-π interactions for the red shift of fluorescence. Because of the meta-amino effect, the feature of high fluorescence quantum yield and high different fluorescence quantum yield between the protic and aprotic solvent are retained. Also, introducing the ester group to the imidazolinone is to enhance the water solubility upon hydrolyzed to the corresponding acid. According to the Hirayama’s rule, the fluorescence could be red-shifted upon the formation of intramolecular exciplex. The ethylbenzene (1) and propylbenzene (2) system provide the correlation of the chain length and the emission wavelength; Introducing the electron withdrawing cyano (3) and electron donating methoxy (4) to would change the donor-acceptor strength. Our results show that there are no red-shifted emission between compound 1-4 in the room temperature. Cause of the meta-amino effect, compound 3, 4 shows blue and red shift fluorescence respectively, and compound 1 is red-shifted by 30 nm at 180 K.
參考文獻
延伸閱讀
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