Surface-enhanced Raman scattering (SERS) is a sensitive analytical technique capable of magnifying the vibrational intensity of molecules adsorbed onto the surface of metallic nanostructures. Various solution-based SERS-active metallic nanostructures have been designed to generate substantial SERS signal enhancements. However, most of these SERS substrates rely on the chemical aggregation of metallic nanostructures to create strong signals. While this can induce high SERS intensities through plasmonic coupling, most chemically aggregated assemblies suffer from poor signal reproducibility and reduced long-term stability. To overcome these issues, here we report for the first time the synthesis of gold core–satellite nanoparticles (CSNPs) for robust SERS signal generation. The novel CSNP assemblies consist of a 30 nm spherical gold core linked to 18 nm satellite particles via linear heterobifunctional thiol–amine terminated PEG chains. We explore the effects that the varying chain lengths have on SERS hot-spot generation, signal reproducibility and long-term activity. The chain length was varied by using PEGs with different molecular weights (1000 Da, 2000 Da, and 3500 Da). The CSNPs were characterized via UV-Vis spectrophotometry, transmission electron microscopy (TEM), ζ -potential measurements, and lastly SERS measurements. The versatility of the synthesized SERS-active CSNPs was revealed through characterization of optical stability and SERS enhancement at 0, 1, 3, 5, 7 and 14 days.
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Surface-enhanced Raman scattering-based molecular encoding with gold nanostars for anticounterfeiting applications
Recently, surface-enhanced Raman scattering (SERS) joined other optical methods in making novel anticounterfeiting materials due to the fact that abundant molecular fingerprints in Raman spectra can be less susceptible to fraud. Using these molecular features, it is critical to make novel nanostructures with increased SERS enhancement and stability. Herein, we synthesized star-shaped gold nanoparticles as SERS substrates and applied various Raman probes with these gold nanostars to make SERS tags. The encoded molecular information was successfully decoded using principal component analysis (PCA). These colloidal tags can be further stabilized when embedded in a polymer matrix. We made a prototype ballpoint pen that can do simple writing with these secret SERS inks.
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- Award ID(s):
- 2018422
- PAR ID:
- 10329506
- Date Published:
- Journal Name:
- Materials Advances
- Volume:
- 2
- Issue:
- 15
- ISSN:
- 2633-5409
- Page Range / eLocation ID:
- 5116 to 5123
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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