Nitrogen-Doping Enhanced Fluorescent Carbon Dots: Green Synthesis and Their Applications for Bioimaging and Label-Free Detection of Au³⁺ Ions

Abstract

Fluorescent carbon dots (CDs) hold great promise for a myriad applications due to their fascinating attributes. However, the development of CDs with high fluorescence quantum yield (QY) and unique surface property is still in its infancy. Herein, we report a simple and green strategy to produce water-soluble nitrogen-doped CDs (N-CDs) via the one-pot hydrothermal carbonization of the mixture of natural peach gum polysaccharide (PGP) and ethylenediamine. The resulting N-CDs exhibit a remarkably enhanced QY (28.46%) as compared with that of undoped CDs (5.31%). In addition, the N-CDs show stable fluorescence against ionic strength variation and pH change. Preliminary biological studies reveal that N-CDs possess low cytotoxicity and high fluorescent contrast in cells. Moreover, we present here for the first time that the obtained N-CDs can exhibit a fast and highly sensitive and selective fluorescence quenching effect toward Au3+ ions. The detection limit can reach 6.4 × 10–8 M, which compares favorably to other reported fluorescent probes. We have also demonstrated that the N-CDs can be employed to sense Au3+ ions in real river water. Considering the easy synthetic process and excellent performance of the N-CDs, this investigation opens up new opportunities for preparing high-quality fluorescent CDs to meet the requirement of many applications.

Biomass‐Derived Carbon Dots and Their Applications

“…The quantum yield of BCDs was increased by N‐doped with ethylenediamine. With the increase in the amount of ethylenediamine added from 50 to 200 mg, the quantum yield of N‐doped BCDs gradually increased from 13.12% to 28.46% . When the amount of ethylenediamine was increased again, the quantum yield value of N‐doped BCDs did not change.…”

“…synthesized BCDs with a low detection limit of 5 n m of Cu 2+ . Liao et al . reported a simple and green strategy to produce BCDs via a HTC of a mixture of natural peach gum polysaccharide and ethylenediamine.…”

The Role of Glutathione and Ethanol in Dictating the Emission Dynamics of Natural Resources‐Derived Highly Luminescent Carbon Nanodots

“…Their optical properties are quite similar and also dependent on the pH of the medium. Recent studies on boron and nitrogen, contents influenced luminescence properties of CNDs also support the reaction mechanism mentioned above that the presence of nitrogen content may result more contribution to π‐conjugation, thus bathochromic shift, whereas the inclusion of boron compounds in precursor may form boronate complex with adjacent hydroxyl groups and thus restricting flexibility and quenching. Moreover, X‐ray Photoelectron spectroscopic (XPS) studies on CNDs indicate the presence of three types of nitrogens ‐ pyridinic (398.1 eV), pyrrolic (399.5 eV) and tertiary nitrogen (401.6 eV) .…”

Nitrogen‐doped carbon dots as a fluorescent probe for the highly sensitive detection of Ag+ and cell imaging

“…CDs have found promising applications in many areas including bioimaging, sensors, medical diagnosis, and so on. Chemical sensing systems based on CDs have been mainly used for the detection of metal ions …”