Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation
Graphene quantum dots (GQDs) represent a class of promising nanomaterials characterized by adjustable optical properties, making them well suited for applications in biosensing and chemical detection. However, challenges persist in achieving scalable, cost-effective synthesis and enhancing detection...
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2025-03-01
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| author | Weitao Li Qian Niu Xinglong Pang Shang Li Yang Liu Boyu Li Shuangyan Li Lei Wang Huazhang Guo Liang Wang |
| author_facet | Weitao Li Qian Niu Xinglong Pang Shang Li Yang Liu Boyu Li Shuangyan Li Lei Wang Huazhang Guo Liang Wang |
| author_sort | Weitao Li |
| collection | DOAJ |
| description | Graphene quantum dots (GQDs) represent a class of promising nanomaterials characterized by adjustable optical properties, making them well suited for applications in biosensing and chemical detection. However, challenges persist in achieving scalable, cost-effective synthesis and enhancing detection sensitivity. In this study, we have developed a simple and environmentally friendly method to prepare blue graphene quantum dots, c-GQDs, using nitronaphthalene as a precursor, and yellow graphene quantum dots, y-GQDs, using nitronaphthalene doped acid. The quantum yield is 29.75%, and the average thickness is 2.08 nm and 3.95 nm, respectively. The synthesized c-GQDs exhibit a prominent cyan fluorescence at a wavelength of 490 nm under excitation at 380 nm, while the y-GQDs show a distinct yellow fluorescence at a wavelength of 540 nm under excitation at 494 nm. The introduction of p-aminobenzoic acid (PABA) introduced a marked red shift in fluorescence, attributed to the electron-withdrawing effect of the carboxyl groups on PABA. This key finding significantly enhanced the sensitivity of GQDs for detecting trace copper(II) ions (Cu<sup>2+</sup>), a heavy metal contaminant posing serious environmental risks. The fluorescence of the GQDs was selectively quenched in the presence of Cu<sup>2+</sup>, facilitating accurate and sensitive detection even in complex ion matrices. Mechanistic studies revealed that the quenching effect is driven by strong static quenching interactions, which inhibit non-radiative transitions. This work not only introduces a scalable method for producing high-performance GQDs but also highlights their potential as effective fluorescent probes for environmental monitoring and heavy metal ion detection. |
| format | Article |
| id | doaj-art-e895f143dbbb437e8988f8606d27d4eb |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-03-01 |
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| series | Molecules |
| spelling | doaj-art-e895f143dbbb437e8988f8606d27d4eb2025-08-20T03:43:25ZengMDPI AGMolecules1420-30492025-03-01306124410.3390/molecules30061244Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing ModulationWeitao Li0Qian Niu1Xinglong Pang2Shang Li3Yang Liu4Boyu Li5Shuangyan Li6Lei Wang7Huazhang Guo8Liang Wang9Textile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaInstitute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaTextile and Garment Industry of Research Institute, Zhongyuan University of Technology, Zhengzhou 450007, ChinaInstitute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, ChinaInstitute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, ChinaGraphene quantum dots (GQDs) represent a class of promising nanomaterials characterized by adjustable optical properties, making them well suited for applications in biosensing and chemical detection. However, challenges persist in achieving scalable, cost-effective synthesis and enhancing detection sensitivity. In this study, we have developed a simple and environmentally friendly method to prepare blue graphene quantum dots, c-GQDs, using nitronaphthalene as a precursor, and yellow graphene quantum dots, y-GQDs, using nitronaphthalene doped acid. The quantum yield is 29.75%, and the average thickness is 2.08 nm and 3.95 nm, respectively. The synthesized c-GQDs exhibit a prominent cyan fluorescence at a wavelength of 490 nm under excitation at 380 nm, while the y-GQDs show a distinct yellow fluorescence at a wavelength of 540 nm under excitation at 494 nm. The introduction of p-aminobenzoic acid (PABA) introduced a marked red shift in fluorescence, attributed to the electron-withdrawing effect of the carboxyl groups on PABA. This key finding significantly enhanced the sensitivity of GQDs for detecting trace copper(II) ions (Cu<sup>2+</sup>), a heavy metal contaminant posing serious environmental risks. The fluorescence of the GQDs was selectively quenched in the presence of Cu<sup>2+</sup>, facilitating accurate and sensitive detection even in complex ion matrices. Mechanistic studies revealed that the quenching effect is driven by strong static quenching interactions, which inhibit non-radiative transitions. This work not only introduces a scalable method for producing high-performance GQDs but also highlights their potential as effective fluorescent probes for environmental monitoring and heavy metal ion detection.https://www.mdpi.com/1420-3049/30/6/1244graphene quantum dots (GQDs)electron-withdrawing modulationcopper detectionnitrogen dopingfluorescence red shift |
| spellingShingle | Weitao Li Qian Niu Xinglong Pang Shang Li Yang Liu Boyu Li Shuangyan Li Lei Wang Huazhang Guo Liang Wang Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation Molecules graphene quantum dots (GQDs) electron-withdrawing modulation copper detection nitrogen doping fluorescence red shift |
| title | Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation |
| title_full | Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation |
| title_fullStr | Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation |
| title_full_unstemmed | Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation |
| title_short | Optimized Sensitivity in Copper(II) Ion Detection: Sustainable Fabrication of Fluorescence Red-Shifted Graphene Quantum Dots via Electron-Withdrawing Modulation |
| title_sort | optimized sensitivity in copper ii ion detection sustainable fabrication of fluorescence red shifted graphene quantum dots via electron withdrawing modulation |
| topic | graphene quantum dots (GQDs) electron-withdrawing modulation copper detection nitrogen doping fluorescence red shift |
| url | https://www.mdpi.com/1420-3049/30/6/1244 |
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