Department of Life Science, University of Seoul, Seoul, 02504, Republic of Korea.
Department of Mechanical Engineering, Sogang University, Seoul, 04107, Republic of Korea.
Small. 2022 Jun;18(24):e2201075. doi: 10.1002/smll.202201075. Epub 2022 May 16.
The assembly of metal nanoparticles and targets to be detected in a small light probe volume is essential for achieving sensitive in-solution surface-enhanced Raman spectroscopy (SERS). Such assemblies generally require either chemical linkers or templates to overcome the random diffusion of the colloids unless the aqueous sample is dried. Here, a facile method is reported to produce 3D multiscale assemblies of various colloids ranging from molecules and nanoparticles to microparticles for sensitive in-solution SERS detection without chemical linkers and templates by exploiting photothermally driven convective flow. The simulations suggest that colloids sub 100 nm in diameter can be assembled by photothermally driven convective flow regardless of density; the assembly of larger colloids up to several micrometers by convective flow is significant only if their density is close to that of water. Consistent with the simulation results, the authors confirm that the photothermally driven convective flow is mainly responsible for the observed coassembly of plasmonic gold nanorods with either smaller molecules or larger microparticles. It is further found that the coassembly with the plasmonic nanoantennae leads to dramatic Raman enhancements of molecules, microplastics, and microbes by up to fivefold of magnitude compared to those measured in solution without the coassembly.
将金属纳米粒子和待检测的目标物组装到小的光探针体积中，对于实现敏感的溶液中表面增强拉曼光谱（SERS）是至关重要的。这种组装通常需要化学连接物或模板来克服胶体的随机扩散，除非水相样品被干燥。在这里，报道了一种简单的方法，通过利用光热驱动的对流流，在无需化学连接物和模板的情况下，生产出各种胶体的 3D 多尺度组装体，范围从分子和纳米粒子到微粒子，用于敏感的溶液中 SERS 检测。模拟表明，直径小于 100nm 的胶体可以通过光热驱动的对流流组装，而与密度无关；只有当较大胶体的密度接近水的密度时，对流流才能显著组装直径达数微米的胶体。与模拟结果一致，作者证实，光热驱动的对流流主要负责观察到的等离子体金纳米棒与较小的分子或较大的微粒子的共组装。进一步发现，与等离子体纳米天线的共组装导致分子、微塑料和微生物的拉曼增强幅度高达五倍，与没有共组装时在溶液中测量的相比。
