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A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions
Published on: February 5, 2016
Tuning size and sensing properties in colloidal gold nanostars
Silvia Barbosa1, Amit Agrawal, Laura Rodríguez-Lorenzo
1Departamento de Química Física and Unidad Asociada CSIC-Universidade de Vigo, 36310 Vigo, Spain.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 1, 2010
Summary
Researchers optimized gold nanostar synthesis by controlling parameters like precursor reduction and seed size. Sharp tips, crucial for surface-enhanced Raman scattering (SERS), were confirmed, though larger sizes increased polydispersity.
Area of Science:
- Nanotechnology
- Materials Science
- Physical Chemistry
Background:
- Gold nanostars exhibit unique plasmonic properties due to their multibranched structure and sharp tips.
- Optimization of synthesis is crucial for tailoring their optical and sensing capabilities.
Purpose of the Study:
- To systematically investigate the influence of synthesis parameters on gold nanostar characteristics.
- To correlate particle morphology, particularly tip sharpness, with optical enhancing behavior in surface-enhanced Raman scattering (SERS).
Main Methods:
- Seeded growth synthesis in poly(vinylpyrrolidone) and N,N-dimethylformamide.
- Varied parameters: controlled prereduction of Au(3+) to Au(+), [HAuCl(4)]/[seed] molar ratio, seed size (2-30 nm), and synthesis temperature.
- Evaluated particle size, morphology, monodispersity, and optical properties.
Main Results:
- Controlled prereduction improved monodispersity, indicated by narrower plasmon bands.
- The [HAuCl(4)]/[seed] ratio significantly impacted morphology and tip plasmon resonance.
- Seed size influenced final dimensions and spike count; temperatures above 60 °C led to rounded morphologies.
- Sharp tips were confirmed essential for SERS enhancement, and larger nanostars showed increased refractive index sensitivity but lower figure of merit due to polydispersity.
Conclusions:
- Synthesis parameters critically control gold nanostar size, morphology, and monodispersity.
- Sharp tips are vital for enhanced optical properties in SERS applications.
- Trade-offs exist between nanostar size, sensitivity, and monodispersity for sensing applications.
