Su Dan, Zhang Xiao-Yang, Chen Xia-Yao, Wang Shan-Jiang, Wan Qing-Dian, Zhang Tong
Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, People's Republic of China.
Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, School of Instrument Science and Engineering, Southeast University, Nanjing 210096, People's Republic of China.
Nanotechnology. 2022 Mar 17;33(23). doi: 10.1088/1361-6528/ac57d3.
Hanging (aggregation stuck to the centrifugal tube) in the centrifugation process is always regarded as an unwanted condition. In this work, we develop a centrifugation-induced assembly of dense hotspots surface-enhanced Raman scattering (SERS) substrates from the hanging phenomenon. We discovered interesting sintering-resistant behavior (maintain the sharp nanotip features) of star-like Au nanoparticles after centrifugation-induced assembly, which is in stark contrast with the sintering phenomenon of sphere-like nanoparticles. We also found that one side of centrifugal-induced Au assemblies is two-dimensional (2D, root mean square (rms) roughness down to ∼10 nm), while the other is three-dimensional (3D, rms roughness more than 100 nm). The close-packed feature of the Au assemblies makes them candidates as dense hotspots based SERS substrates. Through systematic investigation of SERS performance of centrifugation-induced assemblies with different morphology (star-like and sphere-like, 2D and 3D), it was found that the 3D side of star-like Au nanoparticles assembly exhibits the highest SERS enhancement together with quenched fluorescence. The star-like SERS substrate also displays high detection uniformity (with 10M Rhodamine 6G) and a low detection limit (down to 10M Rhodamine 6G).
在离心过程中出现的挂壁现象（聚集物附着在离心管上）一直被视为不理想的情况。在这项工作中，我们利用挂壁现象开发了一种离心诱导组装的致密热点表面增强拉曼散射（SERS）基底。我们发现，离心诱导组装后，星形金纳米颗粒呈现出有趣的抗烧结行为（保持尖锐的纳米尖端特征），这与球形纳米颗粒的烧结现象形成鲜明对比。我们还发现，离心诱导的金组装体的一侧是二维的（2D，均方根（rms）粗糙度低至约10 nm），而另一侧是三维的（3D，rms粗糙度超过100 nm）。金组装体的紧密堆积特性使其成为基于致密热点的SERS基底的候选材料。通过系统研究不同形态（星形和球形、2D和3D）的离心诱导组装体的SERS性能，发现星形金纳米颗粒组装体的3D侧表现出最高的SERS增强以及荧光猝灭。星形SERS基底还具有高检测均匀性（对于10M罗丹明6G）和低检测限（低至10M罗丹明6G）。
