title: A new fluorescent nitrogen-doped carbon dot system modified by the fluorophore-labeled ssDNA for the analysis of 6-mercaptopurine and Hg (II).
abstract: A simple, environmentally friendly hydrothermal method was used to prepare strongly luminescent, nitrogen-doped carbon dots (NCDs) with the use of Chinese yams as a source of carbon and nitrogen. Such NCDs have an average size of 2.7±1.4 nm; they emit blue light at 420 nm and have a quantum yield of up to 9.3%. Thus, carboxyfluorescein (FAM)-DNA macro-molecules were assembled on the surfaces of the NCDs, and stabilised by strong π-π stacking; the so formed hybrid nano-sensors were found to have an ultra-sensitive response to 6-mercaptopurine (6-MP). A strong emission and enhancement of yellow radiation was observed from FAM. Furthermore, due to the specific interactions between DNA and Hg(2+), which resulted in the formation of the T-Hg(2+)-T (T: thymine base) complex - a large, conjugated system, which formed between NCDs, DNA and 6-MP, was broken up. Thus, the fluorescence from FAM was quenched. The detection limits for 6-MP and Hg(2+) were 0.67 and 1.26 nM, respectively. The proposed method was applied for the determination of 6-MP in human serum and Hg(2+) in water samples with satisfactory results.
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Li
authors.affiliation: College of Chemistry, Nanchang University, Nanchang 330031, China; State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China. Electronic address: ynni@ncu.edu.cn.
authors.forename: Yongnian
authors.initials: Y
authors.lastname: Ni
authors.affiliation: School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane 4001, Australia.
authors.forename: Serge
authors.initials: S
authors.lastname: Kokot
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D002244:Carbon / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D027742:Dioscorea / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D060106:Lakes / Q000032:analysis; D057230:Limit of Detection; D015122:Mercaptopurine / Q000032:analysis* / Q000097:blood; D008628:Mercury / Q000032:analysis* / Q000097:blood; D049329:Nanostructures / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000097:blood
chemical_list: D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D014874:Water Pollutants, Chemical; D002244:Carbon; D015122:Mercaptopurine; D008628:Mercury; D009584:Nitrogen
keywords: 6-mercaptopurine; Carbon dots; Chinese yam; FAM-DNA; Fluorescence switching; Mercury ions