Green fluorescent carbon quantum dots functionalized with polyethyleneimine, and their application to aptamer-based determination of thrombin and ATP
Brightly fluorescent carbon quantum dots coated with polyethylenimine (PEI-CDs) were prepared using malic acid and PEI as the precursors. The PEI-CDs have a high quantum yield (41%) and green emission (peaking at 502 nm under 430 nm excitation), both of which are not affected by high ionic strength. The PEI-CDs have a positive charge at physiological pH values and can electrostatically bind aptamers with their negative charge. This is shown for aptamers binding thrombin or ATP. Binding of aptamers results in quenching of fluorescence. If thrombin or ATP are introduced, the respective aptamer will bind them, and the complex is then released from the PEI-CDs. Fluorescence increases in proportion to the analyte concentration. Under optimized conditions, thrombin and ATP can be sensitively and selectively detected by fluorometry with lower detection limits of 1.2 and 13 nM, respectively. The assay was successfully applied to the determination of thrombin and of ATP in spiked serum samples.
KeywordsPEI-CDs Apatmer sensor Green luminescent Fluorescence assay Thrombin detection ATP detection Hydrothermal reaction Malic acid Polyethylenimine Serum analysis
This work was supported by the National Natural Science Foundation of China (21773150), the Natural Science Foundation of Shaanxi Province (2018JM2045).
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Conflict of interest
The authors declare that they have no conflict of interest.