本研究以烏龍茶內的有機化合物做為綠色合成奈米金/銀粒子的還原劑，並以硝酸銀/四氯金酸水溶液做前驅物，先驗證烏龍茶萃取液在生產奈米金/銀粒子上的穩定性，並首次提出以稀釋的方法來改善綠色合成中，如無添加保護劑造成粒徑過大，放置數天便會產生肉眼可見金屬氧化物沉澱等問題，且以此稀釋方法生產的奈米銀溶液，其多分散性指數 (Polydispersity Index, PDI) 約在0.2左右，且平均粒度小於50 nm，其品質已能媲美標準樣品。

In this study, the organic compounds in Oolong tea were served as green reduction agents for the biosynthesis of gold/silver nanoparticles (AuNPs/AgNPs). Simultaneously tetrachloroauric acid/silver nitrate solution was used as a precursor. The first step is to confirm the stability of using Oolong tea extract to produce AgNPs/AuNPs. We proposed a dilution method to the biosynthesis. The method improves the flaw of large particle size and visible metal oxide precipitation caused by no protective agents. The produced AgNPs/AuNPs via the dilution method has a polydispersity index (PDI) about 0.2 and an average particle size less than 50 nm, which has a comparable quality to standard samples.

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