金奈米團簇利用多爪嵌段共聚物的製備與其螢光性質的研究

Abstract

金奈米團簇(Gold Nanoclusters, Au NCs)具有可發光的性質、低毒性且有極小的尺寸，容易在表面進行修飾，使其可應用於離子檢測、生物標記及生物顯影等。利用不同的高分子聚合物合成金奈米團簇，可調控其螢光放光波長和量子效率，並可更進一步修飾表面的配位基團。金奈米團簇的發光的性質主要是由於配體到金属的電荷轉移 (LMCT, ligand-to-metal charge transfer)，利用波長範圍在300 nm - 400 nm光源的激發條件下，可發出不同顏色的光，因此具有在影像及感測方面應用的潛力。本研究首先將多爪數的聚乙二醇聚合合成PEG-p(Glu)，並在各爪數的支鏈修飾上硫醇，將修飾後高分子做為配位基團利用化學還原的方式合成金奈米團簇。實驗發現用NaBH4合成¬出來的金奈米團簇隨著PEG-p(Glu)爪數的改變，會出現兩種放光波長，分別約在460 nm及650 nm，更進一步地利用水浴法加熱合成的金奈米團簇，其放光波長會再次產生變化。金奈米團簇的大小可能受到不同配位基團的化學結構和合成條件的影響，導致螢光出現變化。結果顯示出利用不同爪數的嵌段共聚物合成的金奈米團簇具有控制金奈米團簇放光波長的潛力。Gold Nanoclusters (Au NCs) have luminescent properties, low toxicity, extremely small size, and easy engineered surface modification, which make the gold nanoclusters can be applied in ion detection, biomarking and biological development. Using different functionalized polymers, gold nanoclusters can be synthesized to control the fluorescence emission wavelength, quantum efficiency, and further surface modification. The photoluminescence properties of the Au NCs are originated from ligand-to-metal charge transfer (LMCT), leading to the different emission wavelength under the excitation ranging from 300 nm - 400 nm. The unique luminescent properties of Au NCs possess the potential in the fields of imaging and sensing. In this study, the multi-arm PEG-p(Glu) with different number of arms were synthesized by a ring-opening polymerization method, and further modified with cystamine on the side chain. The thiolated polymers were used as the ligand to synthesize the Au NCs. With the usage of NaBH4 as the reducing agent, the photoluminescence spectra of Au NCs showed two emission wavelengths at 460 nm and 650 nm. Further, the emission wavelength changed again, when the Au NCs were annealed with water bath method. The size of the Au NCs may be affected by the synthesis conditions and the usage of different ligands, resulting in the change of photoluminescence wavelength. The results show that the Au NCs synthesized using multi-arm PEG-p(Glu) have the potential to control the cluster size and emission wavelength.