Facile synthesis of nitrogen-doped carbon dots from pork liver and its sensing of 6-thioguanine based on the inner filter effect

In this work, a facile one-step hydrothermal method was developed to synthesize nitrogen-doped carbon dots (N-CDs) using pork liver. The quantum yield of the prepared N-CDs was as high as 11.74%. The excitation and emission wavelengths of the N-CDs were 329 and 410 nm, respectively. The excitation spectrum of the N-CDs has a big overlap with the absorption band of 6-thioguanine (6-TG), which formed an inner filter effect (IFE) between them. 6-TG acted as an effective absorber in IFE to quench the fluorescence of the N-CDs. The concentration of 6-TG was well linear with the fluorescence quenching intensity of the system from 1 μM to 200 μM. The limit of detection was as low as 0.75 μM. This proposed method was successfully applied in selective and sensitive determination of 6-TG in human serum with recoveries of 96.2–105.3%.