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Assessing Interparticle Spatial Characteristics of DNA-Linked Core–Shell Nanoparticles with or without Magnetic Cores in Surface Enhanced Raman Scattering

Research paper by Zakiya Skeete, Han-Wen Cheng, Jing Li, Christian Salazar, Winny Sun, Quang Minh Ngo, Liqin Lin, Jin Luo, Chuan-Jian Zhong

Indexed on: 25 Jul '17Published on: 18 Jul '17Published in: Journal of Physical Chemistry C



Abstract

Surface-enhanced Raman scattering (SERS) of plasmonic nanoparticles enables their use as nanoprobes for the detection of biomolecules in solutions, which exploits the “hot-spot” arisen from small aggregates of the biomolecule-linked nanoprobes for effective harnessing of the interparticle plasmonic coupling of gold nanoparticles. While a “squeezed” interparticle spatial characteristic has been revealed from the duplex DNA-linked gold nanoparticles as dimers in solution, how this interparticle spatial characteristic is operative for plasmonic nanoparticles containing magnetic components remains unknown. We describe herein new findings of an investigation of the interparticle spatial characteristics of DNA-linked core–shell type nanoparticles consisting of magnetic cores and plasmonic gold or silver shells, focusing on theoretical–experimental correlation in terms of localized surface plasmon resonance and electromagnetic field enhancement. While the simulated enhancement for the DNA-linked dimers of plasmonic magnetic core–gold shell nanoprobes shows an agreement with the experimental data in terms of the squeezed interparticle spacing characteristic, it does not seem to show an agreement between the simulated and experimental results for the dimers involving magnetic core–silver shell nanoprobes. Instead, an agreement was revealed by simulations of the DNA-linked dimers of the nanoprobes at an interparticle spacing of essentially zero. This finding was analyzed in terms of effective thickness of DNA layers on the nanoparticles and the strong magnetic attraction for the core–shell nanoprobes, providing new insight into the control of core composition and shell structure in optimizing the plasmonic coupling and spectroscopic enhancements for SERS-based biomolecular detection.

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