探討金銀核殼奈米粒子於表面增強拉曼散射光譜的應用

Abstract

本研究以簡易水相化學法合成金屬奈米粒子，並以檸檬酸鈉做為還原劑與保護劑來製備金與金銀核殼奈米粒子。在研究中以金奈米粒子做為晶種合成粒徑均勻且穩定的金銀核殼奈米粒子，並透過金奈米粒子濃度來有效控制銀殼厚度。將所合成不同銀殼厚度之金銀核殼奈米粒子利用自組裝技術，固定於APTMS修飾的矽晶圓表面，在實驗中藉由自組裝沈積時間控制金銀核殼奈米粒子的自組裝密度。透過選擇適合銀殼厚度的金銀核殼奈米粒子與自組裝密度所製備的奈米結構，探討其表面在吸附Rhodamine B後能夠產生最佳的表面增強拉曼散射效果的薄膜平台，除此之外也能利用DNA適體(Aptamer)與目標分子結合的系統來針對所偵測的目標分子產生拉曼散射訊號。此方法是利用當DNA適體與目標分子結合時會放出帶有拉曼訊號分子的另一股DNA，而被放出帶有拉曼訊號分子的DNA會接著與固定於奈米結構表面且序列互補的DNA雜合，進而使得拉曼訊號分子靠近金銀核殼奈米粒子自組裝之薄膜平台，進一步產生拉曼散射訊號，藉此偵測目標分子是否出現。本研究所製作之表面增強拉曼散射薄膜平台具有高再現性、極佳的訊號增強效果與低偵測極限(1 nM)等優點。本實驗同時利用腺嘌呤的DNA適體偵測系統來證實此平台於未來展望上也能應用於其他以DNA適體系統的分子偵測。

In this study, we report a feasible aqueous chemical method to synthesize Au core-Ag shell nanoparticles (NPs) with uniform size by seeding growth approach. The concentration of Au NPs plays an important role in growing the different thickness of Ag shell. The study reports the fabrication of monolayer Au@Ag core-shell NPs through the self-assembly of Au@Ag core-shell NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the deposition time of Au@Ag core-shell NPs plays a crucial role in determining the density of Au@Ag core-shell NPs on the surface of the silicon substrate. The appropriate thickness of Ag shell and the density of Au@Ag core-shell NPs were optimized to yield the greatest SERS effect in R6G molecule. The design of signaling aptamer utilizes the target-induced switching between an aptamer/DNA duplex and an aptamer/target complex. SERS signal was enhanced upon the hybridization of the Raman reporter-labelled DNA released from the target-induced displacement with the capture DNA immobilized on the silicon substrate with Au@Ag core-shell NPs film. This substrate shows high reproducibility, strong enhancement and low detection limit (1 nM). The enhancement in DNA-based adenosine detection properties shall be advantageous in applications for other aptamer sensing systems.