π-π stacking-directed self-assembly of nanoplatelets into diversified three-dimensional superparticles for high surface-enhanced Raman scattering

Nan Li; Meiying Zhang; Yongchao Zha; Yingzi Cao; Ying Ma

doi:10.1016/j.jcis.2020.04.088

π-π stacking-directed self-assembly of nanoplatelets into diversified three-dimensional superparticles for high surface-enhanced Raman scattering

J Colloid Interface Sci. 2020 Sep 1:575:54-60. doi: 10.1016/j.jcis.2020.04.088. Epub 2020 Apr 23.

Authors

Nan Li¹, Meiying Zhang², Yongchao Zha², Yingzi Cao², Ying Ma³

Affiliations

¹ Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China; Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology of Ministry of Education, Tsinghua University, Beijing 100084, China. Electronic address: linanbie@jnu.edu.cn.
² Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China.
³ College of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. Electronic address: maying@scut.edu.cn.

PMID: 32361046
DOI: 10.1016/j.jcis.2020.04.088

Abstract

Ordered, hierarchical structures formed from nanoparticle (NP) self-assembly are of interest as they display the synergistic properties of the individual NP. Herein we report a one-pot approach to form and self-assemble gold (Au) nanoplatelets into brick-wall like (BWL) Au superparticles (AuSPs). We employ an aniline (ANI) derivative, N-(3-amidino)-aniline (NAAN) to reduce the Au precursor into Au nanoplatelets in the presence of Br^-1. The corresponding oxidation product, poly (N-(3-amidino)-aniline) (PNAAN) functions as the capping agent and enables the face-to-face self-assembly of Au nanoplatelets into BWL AuSPs via the π-π stacking interaction. Systematically tuning the reaction conditions leads to spherical, mushroom- or cauliflower-like AuSPs. The significant electromagnetic enhancement of AuSPs via the formation of the nanogaps produces high-density hotspots for excellent surface-enhanced Raman scattering (SERS) enhancement, enabling the ultrasensitive SERS assay with detection limit of pM. Moreover, the as-prepared AuSPs exhibited the intense SERS signals under laser excitation with different wavelength and the excellent reproducibility after long-duration exposure in different media. The developed SERS sensor has a great potential for a wide application of bioanalysis, clinic assays and environmental monitoring.

Keywords: Au superparticles; Face-to-face self-assemblies; Nanoprobe; Plasmonics; SERS.