功能化金奈米粒子於生物技術上的應用

Abstract

近幾年來，對於尋找新材料的科學家們，奈米科技的發展已經引起他們極大的研究興趣，例如半導體、金屬團簇及線狀等奈米層級的材料，由於其獨特的物理性質，使其可以應用至作為奈米感測器、催化載體或光電儀器。此外，為了方便觀察量測，金屬奈米粒子也可以隨著實驗的需要，組裝至我們所需要的結構。在多樣化的金屬半導體中，金奈米粒子的研究更是被科學家長久以來的青睞，由於金奈粒子其簡易的修飾性並且具有極高的穩定性，使得金奈米粒子的應用更加地廣泛。因此我們首次將金奈米粒子與醣分子結合，利用簡單地化學修飾將醣分子共價地鍵結至金奈米粒子上，由於金奈米粒子與硫基可以穩定鍵結，因此我們可以使用金奈米粒子為載體，使醣分子可以在金奈米粒子上呈現出多價效應。利用大腸桿菌鞭毛上特定的蛋白質受體與特定的醣分子鍵結，我們可以使用電子顯微鏡直接觀測蛋白質受體的位置，其結合對於高濃度鹽類溶液有相當高的耐受度。我們也利用流通式生物分子感測系統來測量醣分子與特定蛋白質的鍵結強度，金奈米粒子與醣分子的結合不僅可以提供單一醣分子所呈現的選擇性，並且其共價效應甚至強過單一分子的鍵結力。經由我們的研究，相信可以為奈米技術與生物技術的結合提供另一境界的便利性。利用奈米粒子特殊的物性及化性，在生物系統上的觀測甚至可以超越一般傳統的生物觀測模式。Metal and semiconductor nanoparticles coupling with biomolecules have attracted great interests recently because the resulting materials may bring new applications in biological systems. The strong and selective binding of carbohydrate-AuNP to bacterial presents a novel method of labeling specific protein on the cell surface using carbohydrate conjugated nanoparticles. Moreover, in comparison with the conventional sandwich immunoassay, the biomolecule conjugated nanoparticles can provide a relatively easy and direct method to visualize the target receptors on the cell surface under an electron microscope. On the other hands, the multivalent interactions between carbohydrate-AuNPs and target lectins were studied by the SPR technique to quantitatively analyze the binding affinity. The results showed that the binding of mannose encapsulated AuNPs with Con A and galactose encapsulated AuNPs with VAA-I exhibited a strong multivalent effect, and the binding specificity between carbohydrate-AuNP and the lectin was similar to that of the monovalent counterparts. The relative inhibit potency (RIP) values of carbohydrate-AuNPs indicate that the larger size of AuNP and longer ligand length present excellent binding affinity both in interaction with Con A and VAA-I, respectively. Our results demonstrate that gold nanoparticle can serve as an excellent multivalent carbohydrate ligand carrier, providing a new route for designing inhibitors and biological effectors for target proteins.