近年來，非破壞性表面增強拉曼散射在諸多領域蓬勃發展。許多研究皆以金屬奈米粒子作為基材，因為其獨特的表面電漿共振效應，以及銀-金核殼奈米粒子可藉由調控核與殼的尺寸或形狀來改變表面電漿共振效應，並達到比銀奈米粒子更具有穩定性的表面增強拉曼強度。因此，近年來此技術受到很大的關注。而最常合成奈米粒子之製備方法為晶種合成法，然而，此法極為耗時，且製程較為繁複。
因此，本研究利用大氣常壓微電漿合成銀-金核殼奈米粒子，與傳統晶種合成法相比，不僅製程較有效率，且能生成島狀的金殼沉積於銀核之表面。實驗合成之材料會由紫外-可見光光譜以及穿透式電子顯微鏡做檢測，並以微拉曼做應用之研究。
本研究進一步將此材料進行表面增強拉曼散射之研究，發現相較於銀奈米粒子，銀-金核殼奈米粒子有較強以及較穩定的表面增強拉曼訊號。以羅丹明 6G 作為偵測分子，其偵測極限可低至 10-12莫耳濃度。本實驗亦深入探討銀-金核殼奈米粒子在兩步驟大氣常壓微電漿下的生成機制，以及使此材料擁有優秀表面增強 拉曼訊號的可能因素。另外，在檢測生物分子方面，本研究亦以銀-金核殼奈米粒子作為基材，針對三磷酸腺苷進行偵測，研究結果發現其偵測極限可低至 10-6莫耳濃度，顯示出此材料在生物分子感測的可應用性及發展性。

Surface enhanced Raman scattering (SERS) is a non-destructive technology for various applications. Metal nanoparticles have been widely investigated in SERS applications due to their unique localized surface plasmonic resonance (LSPR). Ag-Au core-shell nanoparticles (Ag@Au NPs) allow tuning their LSPR by varying the size and shape of the core or thickness of the shell and even producing more stable SERS activity in comparison with monometallic Ag NPs. Therefore, they have attracted a lot of attention recently. To synthesise this attracted material, seed-mediated growth is the most widely used method. However, conventional synthesis methods are usually timeconsuming and laborious.
Here, we report a facile method to synthesize Ag@Au NPs using an atmosphericpressure microplasma-assisted electrochemistry. In comparison to conventional seedmediated growth, microplasma-assisted method not only can fabricate Ag@Au NPs in a facile and effective process, but also generate nanoisland-like Au shell forming on the Ag core surface. As-produced samples were characterized by UV-vis, TEM, and microRaman carefully.
We further studied the SERS properties of Ag@Au NPs and noticed exceptional enhancement of SERS activity as well as high stability, which showed superior enhancement of SERS than Ag NPs. The limit of detection of rhodamine 6G (R6G) molecules can achieved down to 1 pM. We further studied the possible mechanism of Ag@Au NPs formation in two-step microplasma process and the possible factors that the Ag@Au NPs can process exceptional SERS properties. In addition, for the purpose of bio-molecule sensing, we demonstrate the feasibility of using the Ag@Au NPs as the SERS substrate for detecting the adenosine triphosphate (ATP) molecules. The result shows that the limit of detection of ATP molecules can achieved down to 1μM detection.

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