Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea
Fluorescent carbon dots are nontoxic nanoparticles composed of carbon, exhibiting advantageous properties for applications in bioimaging and functional materials. We present a methodology for synthesizing fluorescent nitrogen-doped carbon dots (N-CDs) using starch, a biopolymer, and urea as the sour...
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| Format: | Article |
| Language: | English |
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MDPI AG
2025-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/30/9/2068 |
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| author | Hikaru Yorozuya Noor E Ashrafi Kazuya Sato Ahatashamul Islam Rikuto Fukae Yusuke Tagashira Toshifumi Iimori |
| author_facet | Hikaru Yorozuya Noor E Ashrafi Kazuya Sato Ahatashamul Islam Rikuto Fukae Yusuke Tagashira Toshifumi Iimori |
| author_sort | Hikaru Yorozuya |
| collection | DOAJ |
| description | Fluorescent carbon dots are nontoxic nanoparticles composed of carbon, exhibiting advantageous properties for applications in bioimaging and functional materials. We present a methodology for synthesizing fluorescent nitrogen-doped carbon dots (N-CDs) using starch, a biopolymer, and urea as the sources of nitrogen, via the microwave-assisted hydrothermal method. Furthermore, the dependence of the fluorescence spectra and fluorescence quantum yield of N-CDs on the initial concentration of urea in the reactant solution was examined, thereby providing a comprehensive understanding of the influence of nitrogen doping on the CDs. The fluorescence of N-CDs was tunable by varying the excitation wavelength. Stronger fluorescence intensity was observed for a moist phosphate salt/N-CD composite, in contrast to the weaker fluorescence exhibited by a dried one. Fluorescence lifetime measurements revealed that the change in fluorescence intensity can be attributed to the suppression of the non-radiative deactivation process. This observation highlights the critical importance of the interaction between water molecules and surface functional groups in controlling the photophysics of the excited state of N-CDs. |
| format | Article |
| id | doaj-art-052b64161f934813ae7b3501cb64c6f0 |
| institution | Kabale University |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj-art-052b64161f934813ae7b3501cb64c6f02025-08-20T03:52:57ZengMDPI AGMolecules1420-30492025-05-01309206810.3390/molecules30092068Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and UreaHikaru Yorozuya0Noor E Ashrafi1Kazuya Sato2Ahatashamul Islam3Rikuto Fukae4Yusuke Tagashira5Toshifumi Iimori6Department of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanDepartment of Sciences and Informatics, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585, JapanFluorescent carbon dots are nontoxic nanoparticles composed of carbon, exhibiting advantageous properties for applications in bioimaging and functional materials. We present a methodology for synthesizing fluorescent nitrogen-doped carbon dots (N-CDs) using starch, a biopolymer, and urea as the sources of nitrogen, via the microwave-assisted hydrothermal method. Furthermore, the dependence of the fluorescence spectra and fluorescence quantum yield of N-CDs on the initial concentration of urea in the reactant solution was examined, thereby providing a comprehensive understanding of the influence of nitrogen doping on the CDs. The fluorescence of N-CDs was tunable by varying the excitation wavelength. Stronger fluorescence intensity was observed for a moist phosphate salt/N-CD composite, in contrast to the weaker fluorescence exhibited by a dried one. Fluorescence lifetime measurements revealed that the change in fluorescence intensity can be attributed to the suppression of the non-radiative deactivation process. This observation highlights the critical importance of the interaction between water molecules and surface functional groups in controlling the photophysics of the excited state of N-CDs.https://www.mdpi.com/1420-3049/30/9/2068carbon dotsstarchrenewable resource |
| spellingShingle | Hikaru Yorozuya Noor E Ashrafi Kazuya Sato Ahatashamul Islam Rikuto Fukae Yusuke Tagashira Toshifumi Iimori Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea Molecules carbon dots starch renewable resource |
| title | Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea |
| title_full | Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea |
| title_fullStr | Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea |
| title_full_unstemmed | Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea |
| title_short | Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea |
| title_sort | synthesis and fluorescence mechanism of nitrogen doped carbon dots utilizing biopolymer and urea |
| topic | carbon dots starch renewable resource |
| url | https://www.mdpi.com/1420-3049/30/9/2068 |
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