{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T06:11:29Z","timestamp":1772777489902,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,7,24]],"date-time":"2021-07-24T00:00:00Z","timestamp":1627084800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/00081\/2020"],"award-info":[{"award-number":["UIDB\/00081\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/05748\/2020"],"award-info":[{"award-number":["UIDB\/05748\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PTDC\/QUI-QFI\/2870\/2020"],"award-info":[{"award-number":["PTDC\/QUI-QFI\/2870\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/4255\/2020"],"award-info":[{"award-number":["UIDB\/4255\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["CEECIND\/01425\/2017"],"award-info":[{"award-number":["CEECIND\/01425\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["IF\/00092\/2014\/CP1255\/CT0004"],"award-info":[{"award-number":["IF\/00092\/2014\/CP1255\/CT0004"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100010198","name":"Ministerio de Econom\u00eda, Industria y Competitividad, Gobierno de Espa\u00f1a","doi-asserted-by":"publisher","award":["RTI2018-099668-BC22"],"award-info":[{"award-number":["RTI2018-099668-BC22"]}],"id":[{"id":"10.13039\/501100010198","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemosensors"],"abstract":"<jats:p>Here we report the rational development of a carbon dot (CDs)-based fluorescent pH nanosensor by employing an active surface preservation strategy. More specifically, citric acid, urea and fluorescein were subjected to a one-pot hydrothermal treatment, which preserved fluorescein-like structures on the surface of the CDs. The obtained CDs showed pH-sensitive green emission, which can be used to determine pH variations from 3.7 to 12.1 by fluorescence enhancement. Moreover, the obtained nanoparticles showed excellent selectivity toward pH, fluorescence reversibility in different pH values, photostability, while being compatible with human cell lines (even at high concentrations). Furthermore, their performance as pH sensors was comparable with reference pH determination procedures. Thus, an active surface preservation strategy was successfully employed to develop fluorescence pH nanosensors in a rational manner and without post-synthesis functionalization strategies, which show potential for future use in pH determination.<\/jats:p>","DOI":"10.3390\/chemosensors9080191","type":"journal-article","created":{"date-parts":[[2021,7,25]],"date-time":"2021-07-25T22:06:21Z","timestamp":1627250781000},"page":"191","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["An Active Surface Preservation Strategy for the Rational Development of Carbon Dots as pH-Responsive Fluorescent Nanosensors"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8806-230X","authenticated-orcid":false,"given":"Ana Carolina P.","family":"Afonso","sequence":"first","affiliation":[{"name":"Chemistry Research Unit (CIQUP), Faculty of Sciences, University of Porto, R. Campo Alegre 687, 4169-007 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8231-1560","authenticated-orcid":false,"given":"Ana Salom\u00e9","family":"Correia","sequence":"additional","affiliation":[{"name":"OncoPharma Research Group, Center for Health Technology and Services Research (CINTESIS), Rua Dr. Pl\u00e1cido da Costa, s\/n, 4200-450 Porto, Portugal"},{"name":"Department of Community Medicine, Health Information and Decision (MEDCIDS), Faculty of Medicine, University of Porto, Alameda Prof. Hern\u00e2ni Monteiro, 4200-319 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1420-5042","authenticated-orcid":false,"given":"Diana","family":"Duarte","sequence":"additional","affiliation":[{"name":"OncoPharma Research Group, Center for Health Technology and Services Research (CINTESIS), Rua Dr. Pl\u00e1cido da Costa, s\/n, 4200-450 Porto, Portugal"},{"name":"Department of Community Medicine, Health Information and Decision (MEDCIDS), Faculty of Medicine, University of Porto, Alameda Prof. Hern\u00e2ni Monteiro, 4200-319 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3291-7713","authenticated-orcid":false,"given":"Ana T. S. C.","family":"Brand\u00e3o","sequence":"additional","affiliation":[{"name":"Chemistry Research Unit (CIQUP), Faculty of Sciences, University of Porto, R. Campo Alegre 687, 4169-007 Porto, Portugal"}]},{"given":"Maria del Valle Mart\u00ednez","family":"de Yuso","sequence":"additional","affiliation":[{"name":"X-ray Photoelectron Spectroscopy Lab., Central Service to Support Research Building (SCAI), University of M\u00e1laga, 29071 M\u00e1laga, Spain"}]},{"given":"Jos\u00e9","family":"Jim\u00e9nez-Jim\u00e9nez","sequence":"additional","affiliation":[{"name":"Department of Inorganic Chemistry, Faculty of Science, University of M\u00e1laga, 29007 M\u00e1laga, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1283-1042","authenticated-orcid":false,"given":"Nuno","family":"Vale","sequence":"additional","affiliation":[{"name":"OncoPharma Research Group, Center for Health Technology and Services Research (CINTESIS), Rua Dr. Pl\u00e1cido da Costa, s\/n, 4200-450 Porto, Portugal"},{"name":"Department of Community Medicine, Health Information and Decision (MEDCIDS), Faculty of Medicine, University of Porto, Alameda Prof. Hern\u00e2ni Monteiro, 4200-319 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8392-9581","authenticated-orcid":false,"given":"Carlos M.","family":"Pereira","sequence":"additional","affiliation":[{"name":"Chemistry Research Unit (CIQUP), Faculty of Sciences, University of Porto, R. Campo Alegre 687, 4169-007 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2410-8430","authenticated-orcid":false,"given":"Manuel","family":"Algarra","sequence":"additional","affiliation":[{"name":"Department of Inorganic Chemistry, Faculty of Science, University of M\u00e1laga, 29007 M\u00e1laga, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5647-8455","authenticated-orcid":false,"given":"Lu\u00eds","family":"Pinto da Silva","sequence":"additional","affiliation":[{"name":"Chemistry Research Unit (CIQUP), Faculty of Sciences, University of Porto, R. Campo Alegre 687, 4169-007 Porto, Portugal"},{"name":"LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Crista, D.M.A., El Mragui, A., Algarra, M., Esteves da Silva, J.C.G., Luque, R., and da Silva, L.P. (2020). Turning spent coffee grounds into sustainable precursors for the fabrication of carbon dots. Nanomaterials, 10.","DOI":"10.3390\/nano10061209"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1039\/C8GC02736F","article-title":"Carbon dots: Synthesis, formation mechanism, fluorescence origin and sensing applications","volume":"21","author":"Liu","year":"2019","journal-title":"Green Chem."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Sharma, A., and Das, J. (2019). Small molecules derived carbon dots: Synthesis and applications in sensing, catalysis, imaging, and biomedicine. J. 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