Reversible “Off–On” Fluorescence of Zn²⁺-Passivated Carbon Dots: Mechanism and Potential for the Detection of EDTA and Zn²⁺

Abstract

Zn-passivated carbon dots (named Z-CDs) were synthesized from zinc gluconate for the first time through a one-step pyrolysis treatment. The mechanism of Zn-enhanced fluorescence was carefully investigated, and a new strategy to passivate the surfaces of CDs by Zn was proposed. Inspired by the complexation reaction between Zn and ethylenediaminetetraacetic acid (EDTA), a reversible "off-on" fluorescent nanosensor for the detection of EDTA and Zn was constructed based on the depassivation and repassivation of Z-CDs, with a limit of detection as low as 3.2 × 10 M and 5.1 × 10 M, respectively. The proposed Z-CD-based nanosensor had been further utilized for EDTA and Zn monitoring in tap water with excellent recovery. To the best of our knowledge, this was the first report of a fluorescence-based sensor of EDTA and a turn-on sensor of Zn based on CDs with reversible detection capability. Also, benefiting from the low toxicity of zinc, Z-CDs were applied for multicolor bioimaging and in vitro detection in cells.

Deep Red Emissive Carbonized Polymer Dots with Unprecedented Narrow Full Width at Half Maximum

“…More importantly, CPDs show the narrowest FWHM of 20 nm, which is far superior to previously reported CDs, commercial organic dyes with deep red fluorescence, and even equal to the best Cd 2+ /Pb 2+ ‐based QDs (FWHM < 30 nm). [ 8,9,28,32,34 − 38 ] In vivo imaging demonstrates that CPDs can serve as outstanding deep red fluorescent probe with excellent biocompatibility and fast clearance with minimal retention postimaging. They are also potentially applied to the fields of drug delivery, photothermal therapy, and photoelectron conversion owing to their deep red excitation and emission, high QY, broad absorption, and extremely narrow FWHM.…”

Evolution and Synthesis of Carbon Dots: From Carbon Dots to Carbonized Polymer Dots

“…of the CPDs by changing the chemical and electronic structure. The common doping elements include nitrogen,79c,86 phosphorus, sulfur, boron,87d,89 and some metals,26c,90 etc. Some recently reported doped CPDs are shown in Table 1 with the synthesis methods and some properties of CPDs.…”

“…raw materials. In addition to the nonmetallic element doping, the metal element doping was also frequently used to regulate CPDs' property and confer CPDs' function 26c,90,91b,92. Chen et al synthesized Gd‐doping CPDs from Gd(NO 3 ) 3 and m‐phenylenediamine by ethanol solvothermal (Figure c).…”

Facile Synthesis of Mg2+‐Doped Carbon Dots as Novel Biomaterial Inducing Cell Osteoblastic Differentiation

“…All the optical and structure characterizations suggested that the new kind of Mg 2+ -doped CDs had been successfully synthesized in the present work, we considered during the process of hydrothermal reaction, the carbohydrate portion was carbonized to form CDs core, simultaneously the Mg 2+ were in situ doped into CDs, interacted with the carboxylate functional groups on the surfaces. [27] Before exploring the application of Mg-CDs in inducing osteoblastic differentiation, the cytotoxicity and cellular uptake of Mg-CDs was tested for MC3T3-E1 cell lines. It could be seen that when the culture dose of Mg-CDs was as high as 800 µg mL −1 , the cell viability could still retain around 80% ( Figure S2a, Supporting Information), demonstrating the low toxicity and excellent biocompatibility of Mg-CDs.…”

“…As we expected, the color of Mg‐CDs solution changed from purple red to bluish violet after adding Magneson I, while the color of CDs without Mg 2+ dopants remained unchanged (Figure S1, Supporting Information). All the optical and structure characterizations suggested that the new kind of Mg 2+ ‐doped CDs had been successfully synthesized in the present work, we considered during the process of hydrothermal reaction, the carbohydrate portion was carbonized to form CDs core, simultaneously the Mg 2+ were in situ doped into CDs, interacted with the carboxylate functional groups on the surfaces …”