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Article

New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications

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Physicochemistry of Carbon Materials Research Group, Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
2
Department of Biochemistry, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland
3
Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland
*
Authors to whom correspondence should be addressed.
Academic Editors: Heesun Yang and Antonio Polimeni
Materials 2021, 14(9), 2454; https://doi.org/10.3390/ma14092454
Received: 11 April 2021 / Revised: 1 May 2021 / Accepted: 5 May 2021 / Published: 9 May 2021
Carbon-based quantum dots are widely suggested as fluorescent carriers of drugs, genes or other bioactive molecules. In this work, we thoroughly examine the easy-to-obtain, biocompatible, nitrogen-containing carbonaceous quantum dots (N-CQDs) with stable fluorescent properties that are resistant to wide-range pH changes. Moreover, we explain the mechanism of fluorescence quenching at extreme pH conditions. Our in vitro results indicate that N-CQDs penetrate the cell membrane; however, fluorescence intensity measured inside the cells was lower than expected from carbonaceous dots extracellular concentration decrease. We studied the mechanism of quenching and identified reduced form of β-nicotinamide adenine dinucleotide (NADH) as one of the intracellular quenchers. We proved it experimentally that the elucidated redox process triggers the efficient reduction of amide functionalities to non-fluorescent amines on carbonaceous dots surface. We determined the 5 nm–wide reactive redox zone around the N-CQD surface. The better understanding of fluorescence quenching will help to accurately quantify and dose the internalized carbonaceous quantum dots for biomedical applications. View Full-Text
Keywords: carbonaceous quantum dots; nitrogen-containing quantum dots; photoluminescence; quenching; intracellular uptake carbonaceous quantum dots; nitrogen-containing quantum dots; photoluminescence; quenching; intracellular uptake
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MDPI and ACS Style

Wiśniewski, M.; Czarnecka, J.; Bolibok, P.; Świdziński, M.; Roszek, K. New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications. Materials 2021, 14, 2454. https://doi.org/10.3390/ma14092454

AMA Style

Wiśniewski M, Czarnecka J, Bolibok P, Świdziński M, Roszek K. New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications. Materials. 2021; 14(9):2454. https://doi.org/10.3390/ma14092454

Chicago/Turabian Style

Wiśniewski, Marek, Joanna Czarnecka, Paulina Bolibok, Michał Świdziński, and Katarzyna Roszek. 2021. "New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications" Materials 14, no. 9: 2454. https://doi.org/10.3390/ma14092454

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