One‐step preparation of red‐emitting carbon dots for visual and quantitative detection of copper ions

Abstract

A one‐step solvothermal method for the preparation of carbon dots with red fluorescence (R‐CDs) was put forward, in which sodium citrate and formamide were chosen as precursors, while formamide was adopted as the solvent. The fluorescence emission peak of the as‐prepared R‐CDs remained the same (600 nm) when the excitation wavelength increased from 490 nm to 560 nm, and the fluorescence quantum yield is 35.3%. Furthermore, the fluorescence intensity of the as‐prepared R‐CDs could be selectively quenched by copper ions, and the mechanism of Cu2+ quenching R‐CDs is the combination of static and dynamic quenching. As a result, the R‐CDs were applied for the construction of a fluorescent sensor without any modification for the quantitative and visual detection of copper ions, which is a typical contaminant in water. The limit of detection for the fluorescent sensor was as low as 5 nmol/L, and it can be used to fast and directly confirm whether the content of copper ions in drinking water meets the criteria of the United States Environmental Protection Agency and the World Health Organization.

Efficient Synthesis of Highly Photo‐stable N‐doped Carbon Quantum Dots and their Applications in Detection and Cellular Imaging of Mercury Ions

“…Moreover, the Raman spectrum characterized the defects or disorders in N‐CQDs (Figure 3a). The relative intensity of the D‐band (amorphous) at 1352 cm −1 and G‐band (crystalline) at 1590 cm −1 was I D /I G =1.04, which showed that the synthesized N‐CQDs were partially amorphous [33] …”

“…The relative intensity of the Dband (amorphous) at 1352 cm À 1 and G-band (crystalline) at 1590 cm À 1 was I D /I G = 1.04, which showed that the synthesized N-CQDs were partially amorphous. [33]…”

Preparation of Carbon Dots with Ultrahigh Fluorescence Quantum Yield Based on PET Waste

“…The fluorescence quenching mechanism can be divided into the following four types: − (1) the internal filter effect quenching mechanism: the added substance can absorb the excitation light of the fluorescent probes or absorb the emitted light of the fluorescent probes so that the fluorescent probes cannot be excited or the emitted light cannot be released; (2) dynamic quenching mechanism: the fluorescent probes in the excited state have a certain collision effect with the added material, and the excited fluorescent probes lose the excitation energy and return to the ground state, causing the quenching of the fluorescence; (3) static quenching mechanism: the quenching of fluorescence was caused by chemical reactions between the fluorescent probes and the added substance to form a nonfluorescent substance; and (4) the combination of dynamic and static quenching mechanisms: the fluorescence of the probe can not only be dynamically quenched but also static quenched by the added substance.…”

Design and Use of a Gold Nanoparticle–Carbon Dot Hybrid for a FLIM-Based IMPLICATION Nano Logic Gate

“… 25 − 27 CDs emitting in the near-infrared window are of significant importance for biological logic functions due to their high electromagnetic radiation penetration depth and minimum autofluorescence of tissue. 28 − 30 Nanohybrids formed between AuNPs and CDs have potential to serve as novel fluorescent nanomaterials, and as such these hybrids can retain the optical properties of both nanoparticles and CDs.…”

“…Carbon dots (CDs) are recently developed fluorescent carbon nanomaterials with excellent optical and structural properties, which can address a variety of logic functions . The CDs are suitable candidates due to their chemical inertness, biocompatibility, facile functionalization, and high photostability. − CDs emitting in the near-infrared window are of significant importance for biological logic functions due to their high electromagnetic radiation penetration depth and minimum autofluorescence of tissue. − Nanohybrids formed between AuNPs and CDs have potential to serve as novel fluorescent nanomaterials, and as such these hybrids can retain the optical properties of both nanoparticles and CDs.…”