Highly sensitive and selective fluorescence sensing and imaging of Fe3+ based on a novel nitrogen‐doped graphene quantum dots

• Published in: Luminescence (Chichester, England) England), 2021-11, Vol.36 (7), p.1592-1599
• Main Authors: Wu, Dongming, Qu, Chaojie, Wang, Jizhong, Yang, Ran, Qu, Lingbo
• Format: Article
• Language: English
• Subjects: Charge transfer; Citric acid; Cytotoxicity; Detection; Ferric ions; Fluorescence; Graphene; Heavy metals; Imaging techniques; Iron; Metal ions; Nitrogen; nitrogen graphene quantum dots; Quantum dots; Quenching; Selectivity; Semicarbazide; Sensitivity; Stability; Synthesis; Toxicity; Water analysis; Water sampling
• ISSN: 1522-7235; 1522-7243
• DOI: 10.1002/bio.4062

A novel nitrogen‐doped graphene quantum dots (N‐GQDs) with a green fluorescence emission was synthesized through microwave method using citric acid and semicarbazide hydrochloride as reactants. The as‐synthesized N‐GQDs exhibited good stability, excellent water solubility, and negligible cytotoxicity. Due to intermolecular charge transfer, ferric ion (Fe3+) has a strong quenching effect on the N‐GQDs. Fluorescence quenching has a linear relationship with the Fe3+ concentration in the range 0.02–12 μM. The detection limit was 1.43 nM. What is more, it is worth mentioning that the obtained N‐GQDs showed high selectivity and sensitivity towards Fe3+. Under the optimum conditions, the addition of 10‐fold copper ions and 100‐fold other metal ions had no influence on the detection of Fe3+ (0.8 μM), which indicated a higher sensitivity compared with that of the reported methods. Due to their excellent properties, the obtained N‐GQDs was successfully applied for sensing and imaging Fe3+ in water samples and HeLa cells. The obtained N‐GQDs showed a highly selective and sensitive response towards ferric ions (Fe3+) through a fluorescence static quenching process over a wide linear range 0.005–60 mmol/L. The detection limit was as low as 1.43 nmol/L. Moreover, the low toxicity and excellent biocompatibility of the N‐GQDs were evaluated through MTT assay on HeLa cells.