Title: Self-assembly of Janus Dumbbell Nanocrystals and Their Enhanced Surface Plasmon Resonance

Abstract

Self-assembly is a critical process that can greatly expand the existing structures and lead to new functionality of nanoparticle systems. Multicomponent superstructures self-assembled from nanocrystals have shown promise as multifunctional materials for various applications. Despite recent progress in assembly of homogeneous nanocrystals, synthesis and self-assembly of Janus nanocrystals with contrasting surface chemistry remains a significant challenge. Herein, we designed a novel Janus nanocrystal platform to control the self-assembly of nanoparticles in aqueous solutions by balancing the hydrophobic and hydrophilic moieties. A series of superstructures have been assembled by systematically varying the Janus balance and assembly conditions. Janus Au–Fe₃O₄ dumbbell nanocrystals (<20 nm) were synthesized with the hydrophobic ligands coated on the Au lobe and negatively charged hydrophilic ligands coated on the Fe₃O₄ lobe. We systematically fine-tune the lobe size ratio, surface coating, external conditions, and even additional growth of Au nanocrystal domains on the Au lobe of dumbbell nanoparticles (Au–Au–Fe₃O₄) to harvest self-assembly structures including clusters, chains, vesicles, and capsules. It was discovered that in all these assemblies the hydrophobic Au lobes preferred to stay together. In addition, these superstructures clearly demonstrated different levels of enhanced surface plasmon resonance that is directly correlated with the Au coupling in the assemblymore » structure. The strong interparticle plasmonic coupling displayed a red-shift in surface plasmon resonance, with larger structures formed by Au–Au–Fe₃O₄ assembly extending into the near-infrared region. Self-assembly of Janus dumbbell nanocrystals can also be reversible under different pH values. In conclusion, the biphasic Janus dumbbell nanocrystals offer a platform for studying the novel interparticle coupling and open up opportunities in applications including sensing, disease diagnoses, and therapy.« less

Authors:

Liu, Fei ^[1]; Goyal, Shailja ^[1]; Forrester, Michael  ^[1];

• Search DOE PAGES for author "Forrester, Michael"
• Search DOE PAGES for ORCID "0000-0003-3063-9975"

Ma, Tao  ^[2];

• Search DOE PAGES for author "Ma, Tao"
• Search DOE PAGES for ORCID "0000-0002-0579-8045"

Miller, Kyle ^[1]; Mansoorieh, Yasmeen ^[1]; Henjum, John ^[1]; Zhou, Lin ^[3]; Cochran, Eric ^[1]; Jiang, Shan  ^[3]

• Search DOE PAGES for author "Jiang, Shan"
• Search DOE PAGES for ORCID "0000-0001-8119-9012"

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+ Show Author Affiliations

1. Iowa State Univ., Ames, IA (United States)
2. Ames Lab., Ames, IA (United States)
3. Ames Lab. and Iowa State Univ., Ames, IA (United States)

Publication Date:

Wed Dec 26 00:00:00 EST 2018

Research Org.:

Ames Laboratory (AMES), Ames, IA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1494935

Report Number(s):

IS-J-9880
Journal ID: ISSN 1530-6984

Grant/Contract Number:  

AC02-07CH11358

Resource Type:

Accepted Manuscript

Journal Name:

Nano Letters

Additional Journal Information:

Journal Volume: 19; Journal Issue: 3; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

77 NANOSCIENCE AND NANOTECHNOLOGY; Janus balance; Janus nanoparticles; plasmonic coupling; self-assembly; superstructures