Lin J.-HChen S.-JLee J.-EChu W.-YYu C.-JCHIEN-CHENG CHANGCHIEN-FU CHEN2022-03-222022-03-22202213858947https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119168503&doi=10.1016%2fj.cej.2021.133070&partnerID=40&md5=186201d7497de6d524863dbab39348b8https://scholars.lib.ntu.edu.tw/handle/123456789/600226To 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. ? 2021 Elsevier B.V.ConcentrationGold nanoclustersMercury ion detectionPaper-based deviceEnvironmental Protection AgencyFlow of fluidsFluorescenceGold compoundsIonsMercury compoundsMicrofluidicsNanoclustersProjectilesComplex testingGold nanoclusterIon detectionMercury ionOn-site testingPaper based devicesPaper substrateTesting procedurePotable water[SDGs]SDG11journal article10.1016/j.cej.2021.1330702-s2.0-85119168503