| 摘要: | 血紅素(Hemoglobin, Hb)，又稱血紅蛋白，是高等生物體內負責運載氧的一種蛋白質。人體內的血紅素由四個亞基構成，分別為兩個α亞基和兩個β亞基，在與人體環境相似的電解質溶液中血紅素的四個亞基可以自動組裝成α2β2的形態，同時種含有血基質(Heme)的蛋白質分子(Protein)，它可以在肺部或鰓部與氧氣分子結合，然後在身體的組織中將結合的氧氣分子釋放。人體的血紅素主要是存在紅血球之中，約占紅血球的重量百分33%左右。在戰場或是重大創傷時需要大量輸血，可以輸捐賑的天然血液。但血液中天然的紅血球存在一些使用上的問題及限制;例如:血球抗體抗原反應，輸血前須血型相合試驗才可輸血，有透過輸血傳染致病原之風險，需儲存於4℃，有末效期限制(35-42天)，同時來源為人體，取得較為困難等。而人造紅血球發展即在希望解決這些問題。 近幾年來人工攜氧載體大量被研究與發展，不僅僅是因為人體需要氧氣並可做為人工替代血液以外，同時人體氧氣的獲得也與許多疾病相關。血紅素(Hb)具有很大的優勢做為攜氧的載體，然而天然血紅素穩定度不高，在某些特定的物理環境下中心的鐵離子被氧化，而導致攜氧能力下降的情形產生，所以為了讓血紅素更將穩定，目前人工攜氧載體都是將血紅素固定或是被保護於固態材料之中例如高分子載體。本研究計劃主要利用金屬有機骨架材料 (Metal-organic Frameworks；MOFs)包覆血紅素形成Hb-based oxygen carriers (HBOCs)並進行攜氧的穩定度及氧氣吸附能力的研究。金屬有機骨架材料-MOFs 是近年來迅速崛起的一種奈米孔洞材料 (nanoporous material)，其藉由金屬離子 (metal ions) 或金屬團簇 (metal clusters) 與有機配位體 (organic linkers) 所構成，不同的組成單元及官能基具有不同的物理或化學性質，同時具有多孔性與高比表面積，因此其應用性非常廣泛。 在此計畫，本實驗室利用綠色水相及乾式機械化學研磨法合成血色素金屬有機骨架生物複合材料，同時也透過蝕刻方式合成血色素中空金屬有機骨架生物複合材，並進一步測試其穩定與攜氧能力，期望開發出新一代新型態攜氧載體，應用在人工血液，氧氣治療及抗氧化疾病上。 ;Hemoglobin (Hb), the iron-containing pigment in red blood, is a protein whose major function is to transport oxygen throughout the body. It consists of a tetrameric porphyrin protein comprising two α- and two β-polypeptide chains, each with an iron-containing heme group capable of binding to an oxygen molecule. Hb is contained within erythrocytes (RBC, red blood cell) of which it forms ~33 wt% in normal individuals, a concentration that is nearly the same as that of Hb in its crystalline state. In military as well as civilian traumatic exsanguinating hemorrhage, rapid loss of RBCs can lead to suboptimal tissue oxygenation and subsequent morbidity and mortality. In such cases, transfusion of whole blood or RBCs can significantly improve survival. However, blood products including RBCs present issues of limited availability and portability, need for type-matching, pathogenic contamination risks, and short shelf-life, causing substantial logistical barriers to their prehospital use in austere battlefield and remote civilian conditions. Thus, oxygen carriers have attracted much attention in the areas of biotechnology and modern medicine in recent years; oxygen is not only extremely crucial for human metabolism, but also relevant with the development of many diseases. As the most important oxygen-transporting metalloprotein, Hb has exhibited great potential as an oxygen carrier, generating the so-called “blood substitute”. However, free Hb molecules are unstable once extracted from red blood cells, and the ferrous ion in Hb is easily oxidized into ferric ion in physiological conditions, leading to the irreversible loss of its oxygen-transporting capacity. Therefore, many studies are working towards the bioengineering of semi-synthetic and synthetic surrogates of RBCs using various cross-linked, polymeric, and encapsulated forms of Hb. These Hb-based oxygen carriers (HBOCs) can potentially provide therapeutic oxygenation when blood or RBCs are unavailable. Herein, we have encapsulated Hb into a metal-organic framework (MOF) material. MOFs are a new class of nanoporous materials constructed by metal-based nodes and organic linkers. Owing to their ultrahigh surface area, regular nanostructured pores, tunable pore size, and permanent porosity, MOFs have been used in diverse applications including biosensing, biomass production, and catalysis. In this project, we will establish de novo, water-based, mechanochemical, and ball milling synthetic methods for preparing different biocomposites of Hb embedded into MOFs (Hb@MOFs). In addition, we will elucidate the stability and oxygen-carrying capability of the Hb embedded in our newly synthesized MOF composites in order to further applications in oxygen and antioxidant therapeutics. |
