Green Preparation of Fluorescent Nitrogen-Doped Carbon Quantum Dots for Sensitive Detection of Oxytetracycline in Environmental Samples

Abstract

Nitrogen-doped carbon quantum dots (N-CQDs) with strong fluorescence were prepared by a one-step hydrothermal method using natural biomass waste. Two efficient fluorescent probes were constructed for selective and sensitive detection of oxytetracycline (OTC). The synthesized N-CQDs were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FT-IR), X-ray photon spectroscopy (XPS), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM), which proved that the synthesized N-CQDs surface were functionalized and had stable fluorescence performance. The basis of N-CQDs detection of OTC was discussed, and various reaction conditions were studied. Under optimized conditions, orange peel carbon quantum dots (ON-CQDs) and watermelon peel carbon quantum dots (WN-CQDs) have a good linear relationship with OTC concentrations in the range of 2–100 µmol L−1 and 0.25–100 µmol L−1, respectively. ON-CQDs and WN-CQDs were both successfully applied in detecting the OTC in pretreated tap water, lake water, and soil, with the recovery rate at 91.724–103.206%, and the relative standard deviation was less than 5.35%. The results showed that the proposed N-CQDs proved to be green and simple, greatly reducing the detection time for OTC in the determination environment.

Protective Effects of Radix Sophorae Flavescentis Carbonisata-Based Carbon Dots Against Ethanol‐Induced Acute Gastric Ulcer in Rats: Anti-Inflammatory and Antioxidant Activities

“…The HRTEM image indicated that RSFC-CDs had a graphite-like crystalline framework with a lattice spacing of 0.278 nm ( Figure 2B ), which was consistent with the (100) planes of graphitic carbon. 27 , 28 The recognizable diffraction peak (2θ=23.7°) in the XRD pattern ( Figure 2D ) revealed an amorphous carbon phase of RSFC-CDs, which corresponded with the HRTEM image. 29

Figure 2 ( A ) Transmission electron microscope (TEM) image of Radix Sophorae Flavescentis carbonisata-based carbon dots (RSFC-CDs).

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Preparation of Multifunctional N-Doped Carbon Quantum Dots from Citrus clementina Peel: Investigating Targeted Pharmacological Activities and the Potential Application for Fe3+ Sensing

“…Moreover, several studies have used biomass waste for obtaining CQDs, including citrus [ 8 , 9 ], kitchen waste [ 10 ], mango peel [ 11 ], banana peel [ 12 ], expired milk [ 13 ], egg shell [ 14 ], and agarose waste [ 15 ], all exhibiting good chemical and optical properties, and obtained carbon dots were applicable for the bioimaging, biosensing, and environmental monitoring. A significant challenge in the fabrication of biomass-derived CQDs represents obtaining CQDs with a high quantum yield.…”

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care—An Updated Review (2018–2021)

“…XPS is used to characterize the electronic state of the elements present on the surface of CDs, their elemental composition, as well as their other surface attributes. In XPS, a beam of X-rays is directed at the CDs specimen, followed by the irradiation of the sample and concurrent measurement of kinetic energy and number of electrons [155,[200][201][202]. Figure 11 demonstrates the ideal XPS spectra for CDs characterization [167].…”