{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,3]],"date-time":"2025-11-03T13:45:50Z","timestamp":1762177550665,"version":"build-2065373602"},"reference-count":26,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,11,16]],"date-time":"2022-11-16T00:00:00Z","timestamp":1668556800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia\/Minist\u00e9rio da Ci\u00eancia, Tecnologia e Ensino Superior (FCT\/MCTES)","award":["UIDB\/00616\/2022","UIDP\/00616\/2022","UIDB\/04565\/2020","UIDP\/04565\/2020","LA\/P\/0140\/2020"],"award-info":[{"award-number":["UIDB\/00616\/2022","UIDP\/00616\/2022","UIDB\/04565\/2020","UIDP\/04565\/2020","LA\/P\/0140\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemosensors"],"abstract":"<jats:p>Azo dyes are widely spread in our day life, being heavily used in cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of dyes into the environment. As emerging pollutants, their detection, particularly in water systems, is a priority. Herein, a fluorescence-based method was employed for the sensitive and selective detection of anionic and neutral azo dyes. Carbon dots (CDs) synthesized from wet pomace (WP), an abundant semi-solid waste of olive mills, were used as probes. An outstanding capability for detection of azo dyes methyl orange (MO) and methyl red (MR) in aqueous solutions was disclosed, which reached a limit of detection (LOD) of 151 ppb for MO. The selectivity of WP-CDs for the anionic azo dye (MO) was established through competitive experiments with other dyes, either anionic (indigo carmine) or cationic (fuchsin, methylene blue, and rhodamine 6G); perchlorate salts of transition metal cations (Cu(II), Co(II), Fe(II), Fe(III), Hg(II), and Pb(II)); and sodium salts of common anions (NO3\u2212, CO32\u2212, Cl\u2212, and SO42\u2212). Evidence has been collected that supports static quenching as the main transduction event underlying the observed quenching of the probe\u2019s fluorescence, combined with a dynamic resonance energy transfer (RET) mechanism at high MO concentrations.<\/jats:p>","DOI":"10.3390\/chemosensors10110487","type":"journal-article","created":{"date-parts":[[2022,11,17]],"date-time":"2022-11-17T03:27:44Z","timestamp":1668655664000},"page":"487","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Detection of Azo Dyes Using Carbon Dots from Olive Mill Wastes"],"prefix":"10.3390","volume":"10","author":[{"given":"Diogo A.","family":"Sousa","sequence":"first","affiliation":[{"name":"Department of Chemical Engineering, Instituto Superior de Engenharia de Lisboa, Instituto Polit\u00e9cnico de Lisboa, 1959-007 Lisbon, Portugal"},{"name":"CQ-VR-Centro de Qu\u00edmica-Vila Real, Universidade de Tr\u00e1s-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal"},{"name":"BSIRG-iBB-Institute for Bioengineering and Biosciences, and Associate Laboratory i4HB\u2014Institute for Health and Bioeconomy, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2946-1498","authenticated-orcid":false,"given":"M\u00e1rio N.","family":"Berberan-Santos","sequence":"additional","affiliation":[{"name":"BSIRG-iBB-Institute for Bioengineering and Biosciences, and Associate Laboratory i4HB\u2014Institute for Health and Bioeconomy, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9068-2847","authenticated-orcid":false,"given":"Jos\u00e9 V.","family":"Prata","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, Instituto Superior de Engenharia de Lisboa, Instituto Polit\u00e9cnico de Lisboa, 1959-007 Lisbon, Portugal"},{"name":"CQ-VR-Centro de Qu\u00edmica-Vila Real, Universidade de Tr\u00e1s-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,16]]},"reference":[{"key":"ref_1","unstructured":"(2022, March 10). Summary Color Additives for Use in the United States in Foods, Drugs, Cosmetics and Medical Devices, Available online: https:\/\/www.fda.gov\/industry\/color-additive-inventories\/summary-color-additives-use-united-states-foods-drugs-cosmetics-and-medical-devices#ftnote3."},{"key":"ref_2","unstructured":"(2022, March 10). Regulation (EC) N\u00ba 1333\/2008 of the European Parliament and of the Council of 16 December 2008 on Food Additives. Available online: https:\/\/eur-lex.europa.eu\/legal-content\/EN\/TXT\/HTML\/?uri=CELEX:02008R1333-20200702#tocId52."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"166431","DOI":"10.1016\/j.ijleo.2021.166431","article-title":"Improvement of SERS for detection of ultra-low concentration of methyl orange by nanostructured silicon decorated with Ag nanoparticles","volume":"231","author":"Nguyen","year":"2021","journal-title":"Optik"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"127105","DOI":"10.1016\/j.foodchem.2020.127105","article-title":"Plasmonic nanoparticles on metal-organic framework: A versatile SERS platform for adsorptive detection of new coccine and orange II dyes in food","volume":"328","author":"Wu","year":"2020","journal-title":"Food Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3834","DOI":"10.1021\/jf400619y","article-title":"Simultaneous determination of banned acid orange dyes and basic orange dyes in foodstuffs by liquid chromatography-tandem electrospray ionization mass spectrometry via negative\/positive ion switching mode","volume":"61","author":"Fang","year":"2013","journal-title":"J. Agric. Food Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2842","DOI":"10.1039\/c1ay05327b","article-title":"Simultaneous voltametric determination of Brilliant Blue and Tartrazine in real samples at the surface of a multi-walled carbon nanotube paste electrode","volume":"3","author":"Ghoreishi","year":"2011","journal-title":"Anal. Methods"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5818","DOI":"10.1021\/jf5006403","article-title":"Dispersive liquid-phase microextraction with solidification of floating organic droplet coupled with high-performance liquid chromatography for the determination of Sudan dyes in foodstuffs and water samples","volume":"62","author":"Chen","year":"2014","journal-title":"J. Agric. Food Chem."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Demchenko, A.P. (2009). Introduction to Fluorescence Sensing, Springer Science & Business Media.","DOI":"10.1007\/978-1-4020-9003-5"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Valeur, B., and Berberan-Santos, M.N. (2012). Molecular Fluorescence: Principles and Applications, Wiley-VCH. [2nd ed.].","DOI":"10.1002\/9783527650002"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1007\/s00604-021-05063-x","article-title":"Terthiophene-functionalized mesoporous silica-based fluorescence sensor for the detection of trace methyl orange in aqueous media","volume":"188","author":"Huang","year":"2021","journal-title":"Microchim. Acta"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"122307","DOI":"10.1016\/j.jssc.2021.122307","article-title":"Highly sensitivity, selectivity chemosensor for methyl orange using upconversion NaBiF4: Yb\/Tm nanosheets","volume":"301","author":"Li","year":"2021","journal-title":"J. Solid State Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1541","DOI":"10.1021\/acssensors.0c00342","article-title":"Sensor Array for the Nanomolar Detection of Azo Dyes in Water","volume":"5","author":"Tropp","year":"2020","journal-title":"ACS Sens."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"126097","DOI":"10.1016\/j.cej.2020.126097","article-title":"One-step hydrothermal preparation of highly stable N doped oxidized carbon dots for toxic organic pollutants sensing and bioimaging","volume":"401","author":"Bogireddy","year":"2020","journal-title":"Chem. Eng. J."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"118514","DOI":"10.1016\/j.saa.2020.118514","article-title":"Sensitive detection of Sudan dyes using tire-derived carbon dots as a fluorescent sensor","volume":"239","author":"Hu","year":"2020","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Zulfajri, M., Dayalan, S., Li, W.-Y., Chang, C.-J., Chang, Y.-P., and Huang, G.G. (2019). Nitrogen-Doped Carbon Dots from Averrhoa carambola Fruit Extract as a Fluorescent Probe for Methyl Orange. Sensors, 19.","DOI":"10.3390\/s19225008"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1016\/j.scitotenv.2018.08.060","article-title":"How an environmental issue could turn into useful high-valued products: The olive mill wastewater case","volume":"647","author":"Sousa","year":"2019","journal-title":"Sci. Total Environ."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Sousa, D.A., Ferreira, L.F.V., Fedorov, A.A., Rego, A.M.B., Ferraria, A.M., Cruz, A.B., Berberan-Santos, M.N., and Prata, J.V. (2022). Luminescent Carbon Dots from Wet Olive Pomace: Structural insights, photophysical properties and cytotoxicity. Molecules, 27.","DOI":"10.3390\/molecules27196768"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Oreopoulou, V., and Russ, W. (2007). Olive Mill Wastewater Treatment. Utilization of By-Products and Treatment of Waste in the Food Industry, Springer.","DOI":"10.1007\/978-0-387-35766-9"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"100318","DOI":"10.1016\/j.jphotochemrev.2019.100318","article-title":"Inner filter effect in fluorescence spectroscopy: As a problem and as a solution","volume":"41","author":"Panigrahi","year":"2019","journal-title":"J. Photochem. Photobiol. C Photochem. Rev."},{"key":"ref_20","first-page":"712A","article-title":"Limit of detection A closer look at the IUPAC definition","volume":"55","author":"Long","year":"1983","journal-title":"Anal. Chem."},{"key":"ref_21","unstructured":"Preus, S. (2022, March 20). a|e\u2014UV-Vis-IR Spectral Software Version 2.2, FluorTools. Available online: www.fluortools.com."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"606","DOI":"10.1039\/an9578200606","article-title":"Some Experiments with Spectrofluorimeters and Filter Fluorimeters","volume":"82","author":"Parker","year":"1957","journal-title":"Analyst"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1021\/ac50052a019","article-title":"Correction of right-angle molecular fluorescence measurements for absorption of fluorescence radiation","volume":"52","author":"Christmann","year":"1980","journal-title":"Anal. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4744","DOI":"10.1039\/b808357f","article-title":"A reassessment of the association between azulene and [60] fullerene. Possible pitfalls in the determination of binding constants through fluorescence spectroscopy","volume":"39","author":"Stella","year":"2008","journal-title":"Chem. Commun."},{"key":"ref_25","unstructured":"(2022, November 03). Dados da Qualidade da \u00c1gua\/Torneiras da Cidade de Lisboa. EPAL, Grupo \u00c1guas de Portugal, 2022. Available online: https:\/\/www.epal.pt\/EPAL\/menu\/%C3%A1gua\/divulga%C3%A7%C3%A3o-de-dados-da-qualidade-da-%C3%A1gua\/controlo-legal\/torneiras-na-cidade-de-lisboa."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Lakowicz, J.R. (2006). Principles of Fluorescence Spectroscopy, Springer. [3rd ed.].","DOI":"10.1007\/978-0-387-46312-4"}],"container-title":["Chemosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2227-9040\/10\/11\/487\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:19:40Z","timestamp":1760145580000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2227-9040\/10\/11\/487"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,16]]},"references-count":26,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2022,11]]}},"alternative-id":["chemosensors10110487"],"URL":"https:\/\/doi.org\/10.3390\/chemosensors10110487","relation":{},"ISSN":["2227-9040"],"issn-type":[{"type":"electronic","value":"2227-9040"}],"subject":[],"published":{"date-parts":[[2022,11,16]]}}}