DataSheet1_Preparation of Plasmonic Ag@PS Composite via Seed-Mediated In Situ Growth Method and Application in SERS.docx

The colloidal polystyrene (PS) was synthesized and decorated with silver nanoparticles (Ag NPs). The plasmonic Ag@PS nanocomposite was prepared by loading Ag NPs on PS microsphere through a seed-mediated in situ growth route. The property of Ag NPs deposited on the PS microsphere could be precisely controlled by adjusting the concentration of the chemicals used in the growth medium. The growth step is only limited by the diffusion of growing species in the growth media to the surface of the Ag seed. The Ag@PS prepared via the in situ growth method exhibited two advantages compared with the self-assembled PS/Ag. First, the high-density of Ag NPs were successfully deposited on the surface of PS as the electroless-deposited Ag seed process, which brings nearly three times SERS enhancement. Second, the rapid preparation process for in situ growth method (half an hour, 10 h for the self-assembled method). The PS/Ag could detect Nile blue A (NBA) down to 10–7 M by SERS. Furthermore, the plasmonic Ag@PS SERS substrate was used for pesticide identification. The on-site monitoring malachite green (MG) from fish was achieved by portable Raman spectrometer, and the limit of detection (LOD) was 0.02 ppm. The Ag@PS substrate has also shown capability for simultaneously sensing multiple pesticides by SERS.

本研究合成了胶体聚苯乙烯（colloidal polystyrene，PS）微球，并对其负载银纳米颗粒（silver nanoparticles，Ag NPs）。通过种子介导原位生长法，将Ag NPs负载于PS微球表面，制备得到等离子体Ag@PS纳米复合材料。可通过调节生长介质中化学试剂的浓度，精准调控沉积于PS微球表面的Ag NPs性能。该生长过程仅受生长介质中生长物种向Ag晶种表面扩散过程的限制。
与自组装PS/Ag复合材料相比，原位生长法制备的Ag@PS具有两大优势：其一，通过化学镀Ag晶种工艺，可在PS表面成功沉积高密度Ag NPs，其表面增强拉曼散射（Surface-Enhanced Raman Scattering，SERS）增强效应可达近三倍；其二，原位生长法制备流程快速，仅需半小时，而自组装法需10小时。
该PS/Ag基底可通过SERS技术检测低至10^–7 M的尼罗蓝A（Nile blue A，NBA）。此外，等离子体Ag@PS SERS基底被应用于农药识别：借助便携式拉曼光谱仪，可实现对鱼类体内孔雀石绿（malachite green，MG）的现场检测，其检出限（limit of detection，LOD）低至0.02 ppm。同时，该Ag@PS基底还可通过SERS技术实现多种农药的同步检测。