期刊
ACS NANO
卷 15, 期 8, 页码 13547-13558出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.1c04326
关键词
gold nanorods; chirality; DNA-mediated assembly; twist-stretch coupling; plasmonic nanoparticles; ion concentration; zeta potential
类别
资金
- National Science Foundation [CMMI 1636356, DMR2011924, ACI-1053575]
- Vannevar Bush DoD Fellowship [ONR N000141812876]
- ONR COVID-19 Newton Award [HQ00342010033]
- U.S. Department of Defense (DOD) [N000141812876] Funding Source: U.S. Department of Defense (DOD)
Gold nanorod dimers bridged by double-stranded DNA exhibit variable chiral configurations depending on the chemical and ionic properties of the solvent medium. The chiral behavior is governed by the twist-stretch coupling of the DNA and intermolecular interactions between nanorods. Changes in depletant or ion concentration of the solvent medium can lead to different classes of configurational responses by the dimers, including chirality-switching behavior.
Gold nanorods assembled in a side-by-side chiral configuration have potential applications in sensing due to their strong chiroptical surface plasmon resonances. Recent experiments have shown that dimers of gold nanorods bridged by double-stranded DNA exhibit variable chiral configurations depending on the chemical and ionic properties of the solvent medium. Here, we uncover the underlying physics governing this intriguing chiral behavior of such DNA-bridged nanorods by theoretically evaluating their configurational free energy landscape. Our results reveal how chiral configurations emerge from an interplay between the twist-stretch coupling of the intervening DNA and the intermolecular interactions between the nanorods, with dimers exhibiting left-handed chirality when the interparticle interactions are dominated by attractive depletion or van der Waals forces and right-handed chirality when dominated by repulsive electrostatic or steric forces. We demonstrate how changes in the depletant or ion concentration of the solvent medium lead to different classes of configurational responses by the dimers, including chirality-switching behavior, in good agreement with experimental observations. Based on extensive analyses of how material properties like nanorod aspect ratio, DNA length, and graft height modulate the free energy landscape, we propose strategies for tuning the environmentally responsive reconfigurability of the nanorod dimers. Overall, this work should help control the chirality and related optical activity of nanoparticle dimers and higher-order assemblies for various applications.
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