Monitoring Early-Stage Nanoparticle Assembly in Microdroplets by Optical Spectroscopy and SERS

作者：Salmon Andrew R; Esteban Ruben; Taylor Richard W; Hugall James T; Smith Clive A; Whyte Graeme; Scherman Oren A; Aizpurua Javier; Abell Chris; Baumberg Jeremy J^*

来源：Small, 2016, 12(13): 1788-1796.

DOI：10.1002/smll.201503513

• dark-field spectroscopy
• microdroplets
• nanoparticle
• SERS

Microfluidic microdroplets have increasingly found application in biomolecular sensing as well as nanomaterials growth. More recently the synthesis of plasmonic nanostructures in microdroplets has led to surface-enhanced Raman spectroscopy (SERS)-based sensing applications. However, the study of nanoassembly in microdroplets has previously been hindered by the lack of on-chip characterization tools, particularly at early timescales. Enabled by a refractive index matching microdroplet formulation, dark-field spectroscopy is exploited to directly track the formation of nanometer-spaced gold nanoparticle assemblies in microdroplets. Measurements in flow provide millisecond time resolution through the assembly process, allowing identification of a regime where dimer formation dominates the dark-field scattering and SERS. Furthurmore, it is shown that small numbers of nanoparticles can be isolated in microdroplets, paving the way for simple high-yield assembly, isolation, and sorting of few nanoparticle structures.

• 出版日期2016-4-6