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

Abstract

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 (Fe 3+ ) has a strong quenching effect on the N-GQDs. Fluorescence quenching has a linear relationship with the Fe 3+ 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 Fe 3+ . Under the optimum conditions, the addition of 10-fold copper ions and 100-fold other metal ions had no influence on the detection of Fe 3+ (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 Fe 3+ in water samples and HeLa cells.

Metal ion sensing with graphene quantum dots: detection of harmful contaminants and biorelevant species

“…26,77 Most GQDs which detect Fe 3+ rely on a high affinity for nitrogen and oxygen surface groups in order to quench PL. 25,72,81,82 For example, it is hypothesised that phenolic groups on the surface of GQDs enhance Fe 3+ specificity, due to electron transfer between the excited state GQD and the d orbital of Fe 3+ , leading to PL quenching. 41,78,83 Many GQD sensors designed to detect Fe 3+ utilise precursors rich in oxygen-containing functional groups.…”

Fluorescent Quantum Dots and Its Composites for Highly Sensitive Detection of Heavy Metal Ions and Pesticide Residues: A Review

“…The static quenching process results from the formation of a non-fluorescent ground state complex (such as iron hydroxide), while the dynamic process is due to coordination between electron-rich NH 2 -and electron-deficient Fe 3+ . However, the majority of GQDs that detect Fe 3+ depend on high affinity for nitrogen and O-containing surface groups for quenching the fluorescence of GQDs [90,105,106]. Currently, sensors based on GQD utilize precursors that are rich in O-containing functional groups to form nitrogen and oxygen groups on the surfaces of QDs.…”

“…Currently, sensors based on GQD utilize precursors that are rich in O-containing functional groups to form nitrogen and oxygen groups on the surfaces of QDs. The surface groups can increase the number of functional groups on oxygen-containing surfaces and However, the majority of GQDs that detect Fe 3+ depend on high affinity for nitrogen and O-containing surface groups for quenching the fluorescence of GQDs [90,105,106]. Currently, sensors based on GQD utilize precursors that are rich in O-containing functional groups to form nitrogen and oxygen groups on the surfaces of QDs.…”

Recent advances in graphene quantum dot-based optical and electrochemical (bio)analytical sensors

“…158 Recently, Wu et al reported a sensitive fluorescent sensing probe for Fe 3+ ion detection in HeLa cells and water samples with a LOD of 1.43 nM in the dynamic range of 0.02-12 mM. 187 Sahub et al used GQDs for the development of an optical pesticide sensor through the enzymatic reaction of choline oxidase (CHOx) and acetylcholinesterase (AchE) for the sensitive detection of organophosphate pesticide in water and food samples. 188 Mondal and their team prepared a N,S-GQD-based fluorescent sensing probe for TNP detection with a LOD of 19.05 ppb.…”

“…158 Recently, Wu et al reported a sensitive fluorescent sensing probe for Fe 3+ ion detection in HeLa cells and water samples with a LOD of 1.43 nM in the dynamic range of 0.02–12 μM. 187…”