Highly Chiroptical Detection with Gold–Silver Bimetallic Nanoclusters Circularly Polarized Luminescence Based on G-quartet Nanofiber Self-assembly
Zhiguang Suo, Xialing Hou, Jingqi Chen, Xiaowei Liu, Yu Liu, Feifei Xing, Yingying Chen, Lingyan Feng
Abstract
Circularly polarized luminescence (CPL) as an intriguing luminescence phenomenon has attracted significant research interests for their chiroptical application, and CPL-active materials have been extensively explored in recent years. Herein, a highly chiroptical sensor was fabricated by the coassembly of G-quartet nanofiber and gold–silver bimetallic nanoclusters. In this, the adenosine 5′-monophosphate (AMP) templated gold–silver bimetallic nanoclusters (AuAg NCs) exhibited an enhanced fluorescence (λex = 356 nm, λem = 475 nm), a 9.42% quantum yield, and a 3.8 μs decay time compared with AMP stabilized Au NCs. In addition, a helical G-quartet-based nanofiber structure (g-fiber) was formed based on the self-assembly of guanosine 5′-monophosphate (GMP). The g-fiber was employed as chiral template for CPL emission by decorating AuAg NCs. Most interesting, the opposite CPL emission was regulated by K+ ion. The dissymmetry factor (glum) of this CPL-active material was up to 10–2. Furthermore, a CPL sensor based on the CPL emission has been developed for l-cysteine detection due to the quenching effect on AuAg NCs. The limit of detection (LOD) was as low as 95.7 nM, ranging from 0.1 to 8 μmol L–1, which was comparable with other analytical methods and materials. Our design presents a new horizon for nanoclusters and provides an entirely new approach for bioassay application.