Preparation of graphene oxide quantum dots from waste toner, and their application to a fluorometric DNA hybridization assay
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A one-pot hydrothermal method was developed for the synthesis of graphene oxide quantum dots (GOQDs). It is making use of toner waste as the precursor and H2O2 as the oxidant. Synthesis takes 4 h and does not require strong acids or complex purification steps and does not produce environmentally harmful metal ions. The GOQDs display blue fluorescence with excitation/emission maxima at 340/445 nm. The feasibility of detecting specific DNA sequence was promoted using polyethyleneimine to modify the GOQDs surface. A method was developed to recognized a specific DNA sequence. This is based on electrostatic aggregation of GOQDs and ssDNA labeled with Dabcyl at the 3′ end, which promotes fluorescence quenching of GOQDs. The possible fluorescence quenching mechanism (which is mainly dynamic) was investigated using the Stern-Volmer equation. When a target sequence was added, which is complementary to the ssDNA, the dabcyl-labeled ssDNA is released due to strict complementary base pairing. This promotes fluorescence recovery of GOQDs. The assay has a 0.17 nM detection limit and a linear range of 0.5–30 nM. The method was used to quantify specific DNA sequences from extracts of genetically modified plant tissues.
KeywordsGraphene oxide quantum dots Dynamic quenching Fluorometric assay DNA Transgenic Nanoprobe
This work was funded by the National Natural Science Foundation of China (NSFC) (Grant 31700862), the Natural Science Foundation for Young Scientists of Shanxi Province (Grant 201601D021109), and Shanxi Province Graduate Education Innovation Program (Grant 2017BY086).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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