Cane Molasses Derived N-Doped Graphene Quantum Dots: Dynamic Quenching Synergistically Photoinduced Electron Transfer for the Instant Detection of Nitrofuran Antibiotics

Abstract

The development of a highly selective, simple, and rapid detection method for nitrofuran antibiotics (NFs) is of great significance for food safety, environmental protection, and human health. To meet these needs, in this work, cyan-color highly fluorescent N-doped graphene quantum dots (N-GQDs) were synthesized using cane molasses as the carbon source and ethylenediamine as the nitrogen source. The synthesized N-GQDs have an average particle size of 6 nm, a high fluorescence intensity with 9 times that of undoped GQDs, and a high quantum yield (24.4%) which is more than 6 times that of GQDs (3.9%). A fluorescence sensor based on N-GQDs for the detection of NFs was established. The sensor shows advantages of fast detection, high selectivity, and sensitivity. The limit of detection for furazolidone (FRZ) was 0.29 μM, the limit of quantification (LOQ) was 0.97 μM, and the detection range was 5−130 μM. The fluorescence quenching mechanism of the sensor was explored by fluorescence spectroscopy, UV−vis absorption spectroscopy, Stern−Volmer quenching constant, Zeta potential, UV−vis diffuse reflectance spectroscopy, and cyclic voltammetry. A fluorescence quenching mechanism of dynamic quenching synergized with photoinduced electron transfer was revealed. The developed sensor was also successfully applied for detecting FRZ in various real samples, and the results were satisfactory.

Fluorometric and colorimetric dual-mode sensing of α-glucosidase based on aggregation-induced emission enhancement of AuNCs

“…S12 and Table S3 (ESI†), K SV increases from 38.83 to 60.91 L mol −1 with the temperature of the quenching system rising from 30 to 70 °C, which suggests that the observed quenching effect arises from DQE. 53 Besides, the calculated K q accords with the standard that K q is less than 2.0 × 10 10 L mol −1 s −1 in DQE. 51 Furthermore, as revealed in Table S1 (ESI†), the fluorescence lifetime of Ce@AuNCs declines from 6.33 to 4.23 μs after the introduction of DCIP, also illustrating the existence of DQE.…”

Peanut shell carbon quantum dots modified with citric acid: amplifying visual detection of fluorescence sensitivity for Cu2+

“…There is a strong coordination interaction between Cu 2+ and the surface oxygens of the PSCA-CQDs. The decay time analysis shows that even after the metal has been quenched, this decay period does not change, indicating that electron transfer is the process of quenching and this type of quenching is static 68 rather than dynamic 69 (Fig. 4c).…”

Ultrasound-Assisted Hydrothermal Synthesis of Highly Fluorescent Sulfur Quantum Dots for Fe3+ Ion and Ascorbic Acid Detection in Real Samples

“…The QY of the SQDs was calculated using the following equation φ = φ ′ × A ′ I ′ × I A × n 2 n ′ 2 where ϕ represents the QY, I stands for the integrated emission intensity of the fluorescent spectra, n denotes the refractive index of the solution, and A is the UV–vis absorbance. The superscript (′) refers to the quinine sulfate …”