金奈米團簇和其奈米複合物之合成及多樣性應用

Abstract

近年來，螢光金奈米粒子因其獨特的光物理和光化學特性，受到廣泛的矚目和研究，甚至在細胞光學顯影上被拿來取代一般的有機染料。和半體體量子點相較比，具有低毒性和高生物相容性的優點。本篇論文主要在探討高生物相容性的螢光金奈米粒子之新穎合成和多元應用。 第一章探討金量子點雙光子螢光特性，利用吸收光譜和感應耦合電漿質譜儀訂出準確的吸收常數，用雙光子激發螢光 (TPEF)和Z-scan訂出雙光子吸收截面積 (σ)，其雙光子吸收截面積值可與水溶性的染劑和量子點相媲美。應用層面上，我們成功的觀察到dextran包覆的螢光金奈米粒子在人類間葉幹細胞中的雙光子共軛焦顯微影像，顯示其優越的生物標定能力和高生物相容性，此種新穎的雙光子吸收材料未來可應用在生物追蹤標定方面。 第二章中，我們首度報導胰島素誘導螢光金奈米粒子的合成和應用。此種胰島素螢光金奈米粒子具有生物穿透性佳的近紅外區螢光，且這種以蛋白質當模版合成的奈米複合材料，具有絕佳的生物相容性和生物活性。在分子生物方面，我們利用胰島素抑制劑去探討胰島素代謝的途徑。細胞層次上，我們測試了胰島素金奈米粒子在細胞顯影和X光電腦斷層掃描的效果，而在活體老鼠降血糖的實驗中，也證明了和市售胰島素的降血糖效果相近，保有胰島素原本的生物活性。 第三章中，我們進一步用人類胰島素合成螢光金奈米粒子，探討活體老鼠對胰島素攝入和胰島素抗組的相關性。利用非侵入式二倍頻光學顯微影像技術探測活體老鼠的脂肪細胞，在有無糖尿病的老鼠上，得到明顯對比之顯影效果。這種細胞對胰島素的攝取可以被定量偵測到，胰島素螢光金奈米粒子可當做代謝標靶診斷代謝疾病第二型糖尿病的早期胰島素抗組現象。

Fluorescent gold nanodots carry quantum-mechanical properties when their sizes are comparable to or smaller than the Fermi wavelength (ca. 1 nm) of conductive electrons. In recent years, Au NDs have attracted great attention and have been intensively studied due to their unique photophysical and photochemical properties, as replacements for the conventional organic dyes in optical cell-imaging. Also, fluorescent Au NDs exhibit superior properties such as low toxicity and high biocompatibility than semiconductor quantum dots. This thesis focuses on the syntheses and versatile applications of novel and highly biocompatible fluorescent gold (Au) nanodots (NDs)/nanoclusters (NCs). Chapter I explores the two-photon induced luminescence of 11-mercaptoundecanoic acid-Au NDs. Using UV-Vis absorption spectroscopy and ICP-MS, we precisely determine the extinction coefficient of 11MUA-Au nanodots. TPA cross section (σ) of Au nanodots was measured from both TPEF and Z-scan methods, for which two-photon cross sections in water surpass many known water-soluble fluorophores and are comparable to that of quantum dots. For practical application, we have successfully demonstrated the labeling capability and high biocompatibility of dextran-coated Au nanodots in vitro using human mesenchymal stem cells (hMSCs) with two-photon confocal microscopy. This new type of TPA absorber holds promise for applications in biological labeling. In chapter II, we report for the first time the insulin-directed synthesis of fluorescent gold NDs. The as-prepared insulin-Au NDs show intense red fluorescence (em: 670 nm, quantum yield: 0.07), excellent biocompatibility and preservation of natural insulin bioactivity in lowering the blood-glucose level. The versatility in applications is demonstrated via fluorescence imaging, X-ray computed tomography, insulin-inhibitor interactions, and preservation of nature insulin bioactivity in lowering the blood-glucose level. In Chapter III, the power of fluorescent human insulin-Au NDs have been illustrated in probing the in vivo cellular insulin uptake and local insulin resistance. Deep tissue sub-cellular profile of insulin-Au NDs uptake can be clearly resolved through a least invasive harmonic generation and two-photon fluorescence microscope. The changes of cellular insulin uptake in the metabolic syndrome can thus be quantitatively probed. Such metabolic probes of insulin-Au NDs can be applied to diagnose insulin resistance, which is an early symptom of metabolic diseases like type II diabetes.