發光金奈米原子簇的合成與應用

Abstract

右旋糖酐是一種複合且具有支鏈的葡聚糖，由於其具有低毒性、生物相容性佳、穩定性高、價格低、親水性與易於進行化學修飾等優點，常被用於生物方面的應用。在本論文中，以右旋糖酐做為還原劑經由一鍋反應法合成表面包覆有右旋糖酐的金奈米原子簇，此右旋糖酐金奈米原子簇直徑約3.4 ± 0.9 奈米，可在紫外光燈下放出強烈的綠色螢光，以370奈米波長的光激發此右旋糖酐金奈米原子簇，其最大放光波長大約在500奈米左右，並且吸收光譜中最大吸收波長出現於290奈米，此右旋糖酐金奈米原子簇螢光量子產率可達2.9%。右旋糖酐分子本身具有高的生物相容性，因此表面包覆有右旋糖酐的金奈米原子簇對於細胞並無明顯的毒性產生，細胞對於右旋糖酐金奈米原子簇的容忍度高達10 μg/μL。右旋糖酐金奈米原子簇在生物探測與生物醫藥方面的研究也在此論文中被討論，此右旋糖酐金奈米原子簇被發現可用來做為細菌的螢光標示劑，增加細菌在螢光顯微鏡下的對比使其易於觀察，另外，也將右旋糖酐金奈米原子簇用來與氧化鐵奈米粒子或矽球反應，進而產生兩種奈米複合物，此奈米複合物皆可被癌症細胞藉由胞吞作用進入癌症細胞中，因此右旋糖酐金奈米原子簇所產生的兩種奈米複合物皆具有潛力用於開發藥物傳遞上的應用。

Dextrans have been widely used in biological applications due to their excellent characteristics such as low toxicity, good biocompatibility, stability, low cost, hydrophilic property, and ease of chemical modification. In this thesis, dextrans were used directly as reducing agents for generation of dextran encapsulated gold nanoclusters (AuNCs@Dextran) with bright photoluminescence from a one-pot reaction. The AuNCs@Dextran are spherical, and the diameter of the AuNCs@Dextran was 3.4 ± 0.9 nm. The AuNCs@Dextran can emit green fluorescence under illumination of UV light, and the maximal emission wavelength of AuNCs@Dextran is ~ 500 nm (λexc= 370 nm). The maximum absorption band appears at the wavelength of 290 nm. The quantum yield of AuNCs@Dextran is ~2.9%, while the zeta potential of the AuNCs@Dextran is -22.17 mV at pH 7. Dextran has good cell biocompatibility, so there is no apparent toxicity found when incubating mammalian cells with the AuNCs@Dextran with the concentration up to 10 μg/μL. Accordingly, the applications of the AuNCs@Dextran in biosensing and biomedicine were explored. It was discovered that the AuNCs@Dextran can be used as good fluorescence labeling agents for bacteria. The bacteria labeled by the AuNCs@Dextran can be clearly observed under a fluorescence microscope. Additionally, it was also discovered that two types of nanocomposites made of AuNCs@Dextran/iron oxide magnetic nanoparticles (Fe3O4@MNPs) and AuNCs@Dextran/SiO2 beads can enter cell through cellular uptake process. The internalization of nanocomposites into cancer cells revealed great potential of these materials for the application of drug delivery. Further studies using the nanocomposites as drug carriers are expected to be realized in the near future.