{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T12:53:13Z","timestamp":1772283193509,"version":"3.50.1"},"reference-count":64,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2023,2,2]],"date-time":"2023-02-02T00:00:00Z","timestamp":1675296000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012632","name":"Nazarbayev University","doi-asserted-by":"publisher","award":["090118FD5315"],"award-info":[{"award-number":["090118FD5315"]}],"id":[{"id":"10.13039\/501100012632","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012632","name":"Nazarbayev University","doi-asserted-by":"publisher","award":["240919FD3938"],"award-info":[{"award-number":["240919FD3938"]}],"id":[{"id":"10.13039\/501100012632","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The development of a fluorescent sensor has attracted much attention for the detection of various toxic pollutants in the environment. In this work, fluorescent carbon dots (N,Zn-CDs) doped with nitrogen and zinc were synthesized using citric acid monohydrate and 4-pyridinecarboxyaldehyde as carbon and nitrogen sources, respectively. The synthesized N,Zn-CDs served as an \u201coff\u201d fluorescence detector for the rapid and sensitive detection of hexavalent chromium ions (Cr(VI)). The zinc metal integrated into the heteroatomic fluorescent carbon dot played a functional role by creating a coordination site for the hydrogen ions that were displaced after the addition of Cr to the solution matrix. The stepwise addition of Cr(VI) effectively quenched the fluorescence intensity of the N,Zn-CDs, and this phenomenon was attributed to the internal filter effect. A low detection limit of 0.47 nmol\/L for Cr(VI) was achieved in the fluorescence experiments. Real water samples were used to evaluate the practical application of N,Zn-CDs for the quantification of Cr(VI). The results show acceptable recoveries and agreement with ion chromatography-ultraviolet spectrometry results. These good recoveries indicate that the fluorescence probe is very well suited for environmental measurements.<\/jats:p>","DOI":"10.3390\/s23031632","type":"journal-article","created":{"date-parts":[[2023,2,2]],"date-time":"2023-02-02T01:53:54Z","timestamp":1675302834000},"page":"1632","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["N,Zn-Doped Fluorescent Sensor Based on Carbon Dots for the Subnanomolar Detection of Soluble Cr(VI) Ions"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1947-4727","authenticated-orcid":false,"given":"Enoch Kwasi","family":"Adotey","sequence":"first","affiliation":[{"name":"Department of Chemical and Material Engineering, Nazarbayev University, Astana 010000, Kazakhstan"}]},{"given":"Mehdi","family":"Amouei Torkmahalleh","sequence":"additional","affiliation":[{"name":"Division of Environmental and Occupational Health Sciences, School of Public Health, University of Illinois at Chicago, Chicago, IL 60612, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2367-9661","authenticated-orcid":false,"given":"Philip K.","family":"Hopke","sequence":"additional","affiliation":[{"name":"Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2479-8582","authenticated-orcid":false,"given":"Mannix P.","family":"Balanay","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Nazarbayev University, Astana 010000, Kazakhstan"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1016\/j.ccr.2018.10.002","article-title":"Metal-organic frameworks in Germany: From synthesis to function","volume":"380","author":"Evans","year":"2019","journal-title":"Coord. 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