| 摘要: | 從不同帶電性穩定劑中所合成的金奈米粒子(AuNPs)，經由中性界面活性劑(Hex-OPE-PEO)在其表面進行修飾反應後，可以利用微胞電動層析法(MEKC)加以分析。利用此方法，我們可以測定表面帶有不同穩定劑的AuNPs之大小和分布情形。在本論文中我們利用此電泳技術研究分別以陰離子型、陽離子型、中性以及兩性離子型界面活性劑為穩定劑所合成的AuNPs的性質。
我們發現，反應物混合方法會影響所合成AuNPs的性質。例如，在陰離子(SDS)系統中使用一次加入合成法可以得到粒徑分布較窄的結果；反之，在陽離子(CTAB)系統中使用分段逐次合成法所得產物之再現性與保存穩定性較佳。在陰、陽離子型界面活性劑中添加飽和芘，都可以在合成過程中有效抑制AuNPs成長反應，得到粒徑較小的產物。
在雙界面活性劑中(中性F127+陽離子或陰離子型界面活性劑)合成AuNPs，若添加還原劑(NaBH4)，易形成粒徑分布廣的產物；若只由F127擔任還原劑，則所得粒徑大小可由F127濃度控制，且分布較小。在兩性離子型界面活性劑(TDAPS)系統中，除了在低濃度(0.1 mM)TDAPS中，否則改變NaBH4濃度、TDAPS濃度或合成方法，對於所合成粒徑並無顯著影響。我們發現在SDS中以一次添加合成法合成AuNPs時，當提高還原劑濃度或在低溫進行合成反應，會得到較小粒徑AuNPs。此外，在SDS系統中使用晶種促進成長法合成AuNPs時，似乎應在適當濃度晶種中以分次少量方式添加HAuCl4和NaBH4，降低新晶種的形成，而在原添加晶種上成長，如此才能合成粒徑分布較窄的AuNPs。
Gold nanoparticles (AuNPs) synthesized in surface stabilizers with different charge polarities can be analyzed by micellar electrokinetic chromatography (MEKC) after undergoing surface modification reaction with a neutral surfactant (Hex-OPE-PEO). By using this approach, the particle sizes and distributions of AuNPs capped with different stabilizers can thus be determined. In the thesis, we utilized this CE-based method to study the properties of AuNPs synthesized in anionic, cationic, neutral, and zwitterionic surfactants, respectively.
We found that mixing reactants in different ways would result in AuNPs with different properties. For example, in the anionic (SDS) system, one-pot synthetic method could produce AuNPs with narrower distribution. On the other hand, in the cationic (CTAB) system, stepwise addition method would generate AuNPs with better reproducibility and storage stability. With the addition of saturated pyrene in anionic and cationic surfactants, particle growth reaction could be suppressed and smaller size of AuNPs would be obtained.
In the binary surfactant system (i.e., neutral F127 + cationic or anionic surfactant), AuNPs with broad size distribution would be produced if another reductant (e.g., NaBH4) was added. Without adding additional reductant, F127 could serve as the only reductant in the system as well as the usual surface stabilizer. In so doing, the size of AuNPs could be regulated by F127 concentration and narrower size distribution would be obtained. In the zwitterionic surfactant (TDAPS), except at low TDAPS concentration (0.1 mM), particle size would not be affected by NaBH4 concentration, TDAPS concentration, and reactant mixing method. In the SDS system of one-pot synthetic method, increasing reductant concentration or lowering reaction temperature would reduce particle size. Furthermore, when the seed-mediated method was used in the SDS system, it seemed that multi-step additions of small amounts of HAuCl4 and NaBH4 into appropriate concentration of seeds would decrease the formation of new seeds and enable the particle growth on the added seeds, and therefore produce AuNPs with narrower distribution. |
