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Monitoring Early-Stage Nanoparticle Assembly in Microdroplets by Optical Spectroscopy and SERS
Andrew R Salmon1,2, Ruben Esteban3, Richard W Taylor2
1Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK.
Small (Weinheim an Der Bergstrasse, Germany)
|February 12, 2016
Summary
This study tracks gold nanoparticle assembly in microfluidic microdroplets using dark-field spectroscopy, revealing key insights into dimer formation for enhanced sensing applications.
Area of Science:
- Nanotechnology and Materials Science
- Biomolecular Sensing
- Microfluidics
Background:
- Microfluidic microdroplets are utilized for biomolecular sensing and nanomaterial synthesis.
- Plasmonic nanostructures in microdroplets enable surface-enhanced Raman spectroscopy (SERS)-based sensing.
- Previous studies lacked on-chip characterization tools for early-stage nanoassembly in microdroplets.
Purpose of the Study:
- To develop and apply on-chip characterization tools for tracking nanoassembly in microdroplets.
- To investigate the early-stage formation dynamics of gold nanoparticle assemblies.
- To enable high-yield assembly, isolation, and sorting of few nanoparticle structures.
Main Methods:
- Utilized a refractive index matching microdroplet formulation.
- Employed dark-field spectroscopy for direct tracking of nanoparticle assembly.
- Performed measurements in flow with millisecond time resolution.
Main Results:
- Successfully tracked the formation of nanometer-spaced gold nanoparticle assemblies in microdroplets.
- Identified a dominant dimer formation regime during assembly.
- Demonstrated the isolation of small numbers of nanoparticles within microdroplets.
Conclusions:
- Dark-field spectroscopy with refractive index matching enables real-time monitoring of nanoassembly in microdroplets.
- Understanding dimer formation dynamics is crucial for optimizing SERS-based sensing.
- Microdroplet technology facilitates efficient assembly, isolation, and sorting of nanoparticle structures.
