Tb<sup>3+</sup>-Based Off–On Fluorescent Platform for Multicolor and Dosage-Sensitive Visualization of Bacterial Spore Marker
Shan Pu, Chaoting Shi, Caizhi Lv, Kailai Xu, Xiandeng Hou, Lan Wu
Abstract
Developing a novel strategy for the sensitive and rapid detection of pathogenic bacterial spores in field or on-site settings will be helpful in minimizing their potential threats to human health, environmental safety, and food safety. In this study, Tb 3+ was combined with glutathione (GSH)-modified copper nanoclusters (CuNCs), and an aggregation-induced emission (AIE) fluorescent probe based on Tb-GSH-CuNCs was fabricated for dipicolinic acid (DPA, a pathogenic bacterial spore marker) sensing. Making use of the competitive binding of Tb 3+ between GSH-CuNCs and DPA, a multicolor sensing of DPA was facilely realized without introducing fluorescent materials as the reference. Due to an “off–on” response mechanism of the AIE fluorescent probe, this multicolor response to DPA exhibited a feature of rich color gradients and highly discriminative color change, allowing a dosage-sensitive visual quantification of DPA. The DPA with a concentration even as low as 0.5 μM can still be identified by the naked eye. Moreover, together with a smartphone app, which can extract the R (red), G (green), and B (blue) values from the probe system, a portable platform can be established for sensitive DPA quantification in the range of 0.5–70 μM, showing great potential for the practical monitoring of DPA in field or on-site settings.