A Carbon‐Dot‐Based Fluorescent Probe for the Sensitive and Selective Detection of Copper(II) Ions

Abstract

Fluorescent carbon dots (CDs) are widely applied for the detection of heavy metal ions due to their nontoxicity, high sensitivity and stability. In this work, CDs were synthesized by a simple and green pyrolysis method without complicated postprocessing procedures and characterized by transmission electron microscope, X-ray diffraction, fourier transform infrared spectroscopy, UV-visible spectrophotometer and fluorescence spectroscopy. The CDs exhibited a relatively narrow size distribution of 3.5-8.6 nm with an average size of 6.1 nm and their surface was decorated with abundant functional groups such as hydroxy and amino groups. They exhibited a strong fluorescent peak at 468 nm with a quantum yield of 25% under 365 nm UV irradiation. The CDs exhibited a strong fluorescence response to 70 μM Cu 2 + with the sensitivity up to 77% due to the complexation between the amino groups decorated on the CD surface and the adsorbed copper ions. They also exhibited short response times of less than 1 min, high response selectivity and good stability. Results and discussion Characterization of CDsThe morphology of the as-prepared CDs was firstly observed by a TEM, as shown in figure 1 A). Some CDs exhibit nearly spherical structure and others exhibit irregular structure. The partially enlarged image of a CD exhibits distinct lattice structure with the lattice spacing of 0.29 nm, which corresponds to the (020) crystal surface. [30] The CDs exhibit a narrow [a] Dr.

Facile Synthesis of Nitrogen-Doped Carbon Dots from Lignocellulosic Waste

“…Meanwhile, the shifting and rise of C–N from 1266 to 1368 cm −1 , implied an increase in graphitic structure after the encapsulation process. Furthermore, the change in position and shape of the C–H bending of N–CDs solution from 725.11 to 771.76 cm −1 confirmed the formation of strong hydrogen bonds between N–CDs and PVA chains [97]. Moreover, an obvious increasing and shifting of C–O and C–O–C species from 1045.87 to 1095.56 cm −1 and 1016.56 to 979.05 cm −1 , respectively were noticed, which indicated that both the oxygen-related surface states and topological defects were increased [98].…”

Preparation of carbon dots with orange emission for Cr(Ш) detection and cellular imaging

“…In order to evaluate the biological applications of OCDs for the determination of Cr(Ш) in living cells, the cytotoxicity against HeLa cells was investigated using MTT colorimetric assays. As shown in Figure 9, 92.5% cell viability was observed Cu(П) 365 0-80.0 5.3 [24] Zn(П) 440 0.14-30.0 0.14 [25] Co(П) 376 0.5-3.0 0.12 [26] Cr(VI) 350 1.0-80.0 0.86 [27] Cr(VI) 360 5.0-100.0 0.12 [28] Cr(Ш) 500 1.0-96.0 0.38 This work after incubating HeLa cells with OCDs (from 0 to 300 μg/mL) even for 36 h. So these OCDs exhibited low cytotoxicity and good biocompatibility to living cells [29], which indicated that the OCDs were novel carbon materials with excellent health friendliness.…”

Carbon-based designer and programmable fluorescent quantum dots for targeted biological and biomedical applications

“…The hydroxyl group, for example, has a specific and strong coordination association with Fe 3+ ions, 89 whereas the carboxylic group has a high affinity for Hg 2+ ions, 90 while the amino group forms complexes by interacting with Cu 2+ ions. 91 Bera et al found that when ruthenium-doped-CDs are amine-functionalized, excitation-dependent emission switches to excitation-independent emission, increasing the QY. They suggested that the excitation independent emission as well as the rise in QY caused by amine modification may be attributed to the transition of many sp 2 arrays into a single type, which decreases cross conjugates and thus boosts the quantum yield.…”