The detection of Mercury(II) ions using fluorescent gold nanoclusters on a portable paper-based device

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2022-02, Vol.430, p.133070, Article 133070
• Main Authors: Lin, Jia-Hui, Chen, Shih-Jie, Lee, Jia-En, Chu, Wei-Yi, Yu, Cheng-Ju, Chang, Chien-Cheng, Chen, Chien-Fu
• Format: Article
• Language: English
• Subjects: Concentration; Gold nanoclusters; Mercury ion detection; Paper-based device
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.133070

[Display omitted] •A portable nanocluster-modified paper analytical device integrated with a syringe for highly sensitive Hg2+ detection.•The CMC-EDC/NHS method attaches AuNCs to the substrate, preventing the AuNCs from leaching.•This platform accumulates the signal of Hg2+ by flowing with increased solution volume.•The platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM. To minimize the need for complex testing procedures, sophisticated instrumentation, and electricity for on-site testing, we demonstrate a simple and portable gold nanocluster (AuNC)-modified paper analytical device integrated with syringe-driven fluid flow to enable highly sensitive mercury ion (Hg2+) detection for environmental monitoring. The device is composed of a paper substrate modified with fluorescent AuNCs (AuNC-paper), which is held within a reusable cartridge connected to a syringe, thus allowing users to flow a large volume of the sample solution through the paper test for greater accumulation of the analyte signal. The metallophilic d10-d10 interaction of Hg2+ with Au+ on the surface of the AuNC-paper induces fluorescence quenching, which can be monitored using a smartphone. Importantly, the red-emitting AuNCs avoid interference with the background fluorescence of the paper substrate. Additionally, the AuNCs are strongly-attached to the paper substrate via carbodiimide coupling, which helps prevent the AuNCs from leaching and enables a large amount of solution to interact with the test (up to 2.5 mL) to increase the amount of the target ions that react with the AuNC-paper. As a result, without the need for preconcentrating the test solution, this paper device can provide the highly sensitive detection of Hg2+ ions, including a 26-fold higher sensitivity than the AuNC-modified test paper without a fluidic cartridge, at a low level of down to nM. The paper platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM, which is less than the United States Environmental Protection Agency’s regulatory limit for drinking water. This highly sensitive, selective, portable, and easy-to-operate platform may be valuable for on-site mercury pollution monitoring in resource-constrained settings.