Hydrothermal Synthesis of Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for the Detection of Dopamine

Abstract

Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized though a facile, economical and straightforward hydrothermal method by using polyacrylamide as both carbon and nitrogen sources. The as-prepared N-CQDs offered high quantum yield of 23.1%, exhibited good water solubility and fluorescence properties. Moreover, the N-CQDs can be used as effective probes for sensitive and selective detection of dopamine. Fluorescence of N-CQDs was effectively quenched after the addition of dopamine owing to dopamine would be transformed into dopamine-quinone under alkaline conditions. A good linear relationship between fluorescence quenching and the concentration of dopamine in the range 0.1-200 μM was obtained with a low detection limit of 0.05 μM. The proposed method showed high selectivity for dopamine in the presence of potential interfering species. Moreover, this method was successfully applied to the determination of DA in urine sample with satisfactory recoveries.

Carbon and graphene quantum dots: a review on syntheses, characterization, biological and sensing applications for neurotransmitter determination

“…These N-CQDs with the average diameter of 3 nm displayed reasonable water solubility and the uorescence features so that they could be utilized as efficient probes for sensitively and selectively detecting dopamine (DA). 54 Solvothermal carbonization and then extraction with the organic solvent has been known as one of the well-known approaches to produce the CQDs. 55 In this method, carbonyielding raw materials are exposed to treat the heat in the increased boiling point organic solvents, which is accompanied by the concentration and extraction processes.…”

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“…For example, Tan et al have prepared N-doped CDs pyrolytically from graphene quantum dots using polysaccharide chitosan as a precursor [18]. Similarly, in a most recent work [19], N-doped carbon dots were prepared by an economical and straight forward approach which consists of hydrothermal treatment of poly(acrylamide) as both carbon and nitrogen sources. Likewise, Li et al have reported synthesis of N-doped carbon dots using 1,2-diaminobenzene as the carbon source and dicyandiamide as the dopant [20].…”

Carbon Dots: An Innovative Tool for Drug Delivery in Brain Tumors

“…The difference between C-dots and graphene quantum dots is, instead, mainly linked to their morphology, the first being spherical particles, while the second are better described as zero-dimensional graphene disks [65]. The synthetic strategies leading to the production of C-dots can be broadly divided into top-down and bottom-up approaches (Table 1) [66,67]: the former includes the fragmentation of starting carbonaceous materials using physical or chemical methods (e.g., electrochemical synthesis [68][69][70][71][72][73], chemical oxidation [74][75][76][77][78][79], arc discharge [61,[80][81][82], and laser ablation [62,[83][84][85][86]); the latter starts from molecular precursors and consists, among others, of ultrasound [87][88][89] and hydrothermal [90][91][92][93][94][95] treatments, microwave-assisted synthesis [96][97][98][99][100][101], and pyrolysis or carbonization of the reactants [102][103][104]…”