Microchimica Acta

, 185:540 | Cite as

An enzymatic ratiometric fluorescence assay for 6-mercaptopurine by using MoS2 quantum dots

  • Feng Zhang
  • Hua Liu
  • Qing Liu
  • Xingguang SuEmail author
Original Paper


A ratiometric fluorescence method is described for the determination of the anticancer drug 6-mercaptopurine (6-MP). The method is based on the use of fluorescent MoS2 quantum dots (MQDs) and of the enzyme horseradish peroxidase (HRP). In the absence of 6-MP, HRP catalyzes the oxidation of o-phenylenediamine (OPD) by H2O2 to form 2,3-diaminophenazine (DAP). This leads to quenching of the violet fluorescence of MQDs (measured at excitation/emission wavelengths of 360/415 nm), while the strong yellow fluorescence of DAP (peaking at 560 nm) becomes increasingly strong. In the presence of 6-MP, however, it will be preferentially oxidized by the HRP/H2O2 system to form a disulfide dimer. Hence, less H2O2 is available for the oxidation of OPD and less DAP will be formed. This results in the recovery of the violet fluorescence and a decrease of the yellow fluorescence. The ratio of the two signals can be used to quantify either H2O2 or 6-MP. Linear responses are observed for H2O2 in 0.5–140 μM concentration range, and for 6-MP in the 0.5–70 μM concentration range, with detection limits of 0.1 μM and 0.29 μM, respectively. The method was applied to the determination of 6-MP in spiked human urine and gave satisfactory results.

Graphical Abstract

Schematic of an enzymatic fluorometric method for determination of 6-mercaptopurine (6-MP). It is based on the presence of 6-MP that can inhibit the HRP-catalyzed oxidation of o-phenylenediamine (OPD) to form 2,3-diaminophenazine (DAP). Hence, the fluorescence resonance energy transfer (FRET) between DAP and MoS2 quantum dots (MQDs) is suppressed.


Hydrogen peroxide Fluorometry Ortho-phenylenediamine H2O2 Ratiometric fluorescence Horseradish peroxidase 2,3-diaminophenazine Fluorescence resonance energy transfer 



This work was supported by the National Natural Science Foundation of China (No. 21775052 and No. 21575048), the Science and Technology Development project of Jilin province, China (No. 20180414013GH).

Compliance with ethical standards

The author(s) declare that they have no competing interests.

Supplementary material

604_2018_3039_MOESM1_ESM.doc (777 kb)
ESM 1 (DOC 777 kb)


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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Analytical Chemistry, College of ChemistryJilin UniversityChangchunChina
  2. 2.State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of ChemistryNankai UniversityTianjinChina

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