Site-selective growth and plasmonic spectral properties of L-shaped Janus Au-Ag gold nanodumbbells for surface-enhanced Raman scattering

Hui-Fang Du; Jian Zhu; Guo-Jun Weng; Jian-Jun Li; Xin Li; Jun-Wu Zhao

doi:10.1016/j.saa.2023.122862

Site-selective growth and plasmonic spectral properties of L-shaped Janus Au-Ag gold nanodumbbells for surface-enhanced Raman scattering

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Oct 15:299:122862. doi: 10.1016/j.saa.2023.122862. Epub 2023 May 21.

Authors

Hui-Fang Du¹, Jian Zhu², Guo-Jun Weng¹, Jian-Jun Li³, Xin Li¹, Jun-Wu Zhao⁴

Affiliations

¹ The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, China.
² The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, China. Electronic address: zhujian@mail.xjtu.edu.cn.
³ The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, China; Research Institute of Xi'an Jiaotong University, Floor 5, Block A, Jiangning Mansion, No. 328, Wenming Road, Xiaoshan District, Hangzhou, Zhejiang, China.
⁴ The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, China. Electronic address: nanoptzhao@163.com.

PMID: 37220676
DOI: 10.1016/j.saa.2023.122862

Abstract

Ligand-mediated interface control has been broadly applied as a powerful tool in constructing asymmetric multicomponent nanoparticles (AMNP), and induces the anisotropic growth with fine-tuning morphology, composition, plasmonic property and functionality. As a new kind of AMNP, the synthesis of Janus Au-Ag nanoparticles with tunable negative surface curvature is still a challenge. Here, we demonstrate that the synergistic surface energy effects between gold nanodumbbells (Au NDs) with a negative surface curvature and 4-mercaptobenzoic acid (4-MBA) can direct the site-selective growth of anisotropic silver domains on gold nanodumbbells (Au NDs@Ag NPs). By adjusting the 4-MBA concentration-dependent interfacial energy, the Au NDs@Ag NPs could be continuously tuned from dumbbell-like core-shell structures, to L-shaped Janus, and then rod-like core-shell structures with directional and asymmetric spatial distributions of resizable Ag domains by site-selective growth. Based on the calculation results of discrete dipole approximation (DDA) method, it has been found that the Au NDs@Ag L-shaped Janus NPs with Ag island domains created polarization orientation-dependent plasmonic extinction spectra and hot spots around the negatively curved waist and Ag domains. The L-shaped Janus Au NDs@Ag NPs exhibited significantly plasmonic spectrum properties with four apparent LSPR peaks that cover from visible to near-infrared range and higher surface-enhanced Raman scattering (SERS) activity compared with the original Au NDs. The best SERS enhancement factor of 1.41 × 10⁷ was achieved. This synergistic surface energy effect-based method involving the asymmetric growth of silver coating on gold nanoparticles with negatively curved surface presents a new method to design and fabricate nanometer optical devices based on asymmetric multicomponent nanoparticles.

Keywords: 4-MBA; Asymmetric growth; Au NDs@Ag L-shaped Janus NPs; Gold nanodumbbells; Negative curvature; surface-enhanced Raman scattering.