研究與設計樹枝狀分子錯合物催化氧氣還原之特性及生物應用

Design and characterization the catalytic ability of metallodendrimers in oxygen reduction and their potential biological application

湯宜璇(Yi-Hsuan Tang)

指導教授 ： 陳義龍

共同指導教授 ： 高佳麟(Chai-Lin Kao)

高雄醫學大學/生命科學院/醫藥暨應用化學系博士班/博士(2016年)

摘要

氧氣還原為重要的化學反應。氧氣還原反應會生成超氧陰離子、過氧化氫及氫氧自由基，反應過程中伴隨四個電子的轉移。樹枝狀分子為一個可精準調控其分子量、分子大小及官能基之間的距離。此論文探討，選用不同代數的聚乙二胺樹枝狀分子，外圍修飾?m啶環，所得之化合物用以鍵結銅離子以形成的錯合物，研究中主要探討其催化氧氣還原的活性及特性及生物領域的應用。此論文修飾及製備第二代至第七代聚乙二胺樹枝狀分子且當此類錯合物有還原劑存在時，可生成超氧陰離子。動力學實驗數據指出，在高代數下的樹枝狀分子對氧氣有極佳的親和性，是由於在高代數下的樹枝狀分子其催化中心為雙核銅離子所組成。相反地，低代數則以單核銅離子催化氧氣。同時第五代樹枝狀分子錯合物也展現超氧化物歧化酶的活性，將超氧陰離子還原成過氧化氫。進一步發現此類錯合物可生成氫氧自由基，用來模擬核酸酶之特性。且樹枝狀分子的大小與核酸酶的活性有正相關。最高代數樹枝狀分子相較於最低代數樹枝狀分子與核酸的親和性相比，相差約100倍。這個實驗我們發現樹枝狀分子錯合物未來可在生物應用上作為核酸酶之模型。也利用電化學實驗證實，此樹枝狀分子錯合物可催化四個電子轉移，將氧氣還原至水分子。

關鍵字

樹枝狀分子 ； 銅離子 ； 氧氣還原 ； 協同作用

並列摘要

Oxygen reduction is an important chemical reaction. Reduction of oxygen to H2O accompany with releasing of four electrons. Dendrimer is a well-defined macromolecule with precise size and tunable distance between peripheral functional groups. Superoxide anion radical, peroxide and hydroxyl radical were sequently generated during the reduction and each transformation accompanies one electron transfer. This investigation studied catalytic behavior of modified PAMAM dendrimers copper complexes in this reactions and their potential biological application. G2 to G7 modified PAMAM dendrimers complexes were designed and prepared. The resulting complexes were found to generate superoxide anion radical in the presence of DTT. According to kinetic measurement, binding affinity of higher-generation of dendrimers complexes to oxygen was significantly higher than low generation ones. Further analysis suggested the existence of bicopper active center in high-generation dendrimer complexes. Meanwhile, the prepared dendrimer complexes were found to exhibit reagent dependent superoxide dismutase. Meanwhile, the generation of hydroxyl radical was observed in the DNA cleavage experiment with prepared dendrimer complexes. Meanwhile, positive correlation was observed between size of metallodendrimers and their nuclease activity. Further experiments indicated higher generation of metallodendrimers exhibited 100 times more binding affinity with nucleic acid than lower generation ones. Finally, electrochemical experimental data reported that metallodendrimer have an ability to transfer four electrons to catalyze oxygen reduction to H2O.

並列關鍵字

dendrimer ； copper ions ； oxygen reduction ； cooperation

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