Nitrogen-doped carbon dots as a probe for the detection of Cu²⁺ and its cellular imaging

Abstract

Nitrogen-doped carbon dots were synthesized using citric acid monohydrate and glutathione as raw materials. The synthesized nitrogen-doped carbon dots were characterized by multiple analytical techniques, including transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and fluorescence spectra. The fluorescence intensity of the nitrogen-doped carbon dots gradually quenched with different concentrations of Cu2+ ions. The effect of the pH value, the nitrogen-doped carbon dot concentration, and the reaction time on the fluorescence intensity of the N-CDs-Cu2+ system was investigated, and the experimental conditions were optimized. A rapid and sensitive method for the determination of Cu2+ ions was established that exhibited a good linearity in the concentration range 0.20–200.0 μM with a detection limit of 0.27 nM. Meanwhile, the fluorescence quenching mechanism of the interaction between nitrogen-doped carbon dots and Cu2+ was preliminarily discussed. The method was used to detect trace Cu2+ in tap water and lake water, with recoveries ranging from 98.1% to 102.0%. Furthermore, due to low cytotoxicity and good biocompatibility, nitrogen-doped carbon dots as a probe were also successfully used in bioimaging.

Facile synthesis of Bi2Se3/nitrogen-doped carbon dot nanoplates for aqueous zinc ion battery cathodes

“…The high-resolution XPS pattern of N 1s showed three peaks at 400.39, 399.49 and 398.99 eV, which proved the presence of N–H, pyrrole nitrogen and pyridine nitrogen. 53 In summary, the above results indicate that the surfaces of Bi 2 Se 3 /NCD composites are abundant in functional groups, for example, amino and carbonyl groups, which are consistent with the above FTIR results. The content of NCDs in Bi 2 Se 3 /NCD composites was determined using the TGA method.…”

Advances in carbon quantum dot technology for food safety: preparation, modification, applications and mechanisms

“…By doping the internal structure of CQDs with new elements, the CQDs can have stronger fluorescence, better biocompatibility and improved fluorescence stability. Wang et al [64] prepared nitrogen-doped CQDs with citric acid as carbon precursor and glutathione as nitrogen source for the sensitive detection of Cu 2+ , and achieved a detection limit of 0.27 nM with the range 0.20∼200.0 μM. Wu et al [65] used citric acid and urea as raw materials to prepare nitrogen-doped CQDs by a hydrothermal method.…”

Preparation of carbon quantum dots from corn straw and their application in Cu2+ detection

“…Furthermore, paramagneticism makes Cu 2+ more easily adsorbed on the surface of CQDs (Murugan et al 2019). Thus, the fluorescence of CQDs may be quenched by Cu 2+ via electron transfer, in which Cu 2+ acts as an electron acceptor to block the electron-hole link (Hu et al 2014;Wang et al 2019). Corn straw was successfully used as a raw material for hydrothermally producing carbon quantum dots (CQDs), which were used as a sensor for copper ions.…”