Two-Step Hydrothermal Preparation of Carbon Dots for Calcium Ion Detection

Abstract

It is well known that the calcium ion is essential for maintaining life activities in living organisms, and it is of great significance to detect the intracellular calcium concentration. For the detection of calcium ions, we developed a new type of fluorescent carbon dots (CDs), whose surface was modified by ethylenebis­(oxyethylenenitrilo)­tetraacetic acid (EGTA) through a secondary hydrothermal method. This is a simple and convenient chemical preparation method because all reactions are carried out in the same autoclave, and the final product is directly the EGTA-modified CDs. The CDs exhibit bright blue fluorescence, and as the calcium concentration increases, the fluorescence intensity drops sharply. The fluorescence quenching correlates with the concentration of calcium ions and has a good linearity in the range of 15–300 μM with a detection limit of 0.38 μM. The experimental results confirmed that the detection of calcium ions by CDs is a static fluorescence quenching process. Also, cytotoxicity test and cellular imaging experiments have shown that the CDs are nontoxic and biocompatible.

One-Step Synthesis of Green Fluorescent Carbon Dots for Chloride Detecting and for Bioimaging

“…Yang et al reported the detection of Fe 3+ with blue fluorescent carbon dots and investigated its detection mechanism (Song et al, 2014). Li et al realized the detection of the calcium ion by carbon dot-modified Ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) (Yue et al, 2019). Cao et al used carbon dots to detect progesterone concentration based on the oxidation-reduction mechanism (Cao et al, 2020).…”

The synthesis and modification of highly fluorescent carbon quantum dots for reversible detection of water‐soluble phosphonate‐1‐hydroxyethane‐1,1‐diphosphonic acid by fluorescence spectroscopy

“…Furthermore, when combined with the fitted τ 0 value in Table S2, k q was further calculated as 6.14 × 10 11 M −1 s −1 , which is obviously higher than 1 × 10 11 M −1 s −1 . As the k q values of dynamic pathways were less than 1 × 10 11 M −1 s −1 , this study could be judged as static quenching rather than dynamic quenching [47,48] …”

Chitosan-based carbon nanoparticles as a heavy metal indicator and for wastewater treatment

“…12 CDs from biomaterials 13 have good biocompatibility, stable uorescence properties, non-toxic and great prospects in this eld. [14][15][16][17] Chitosan, 18,19 as a linear polysaccharide linked by b-glucoside bond, is the product of deacetylation of chitin widely distributed in nature. 20 Because of its easy availability and good biocompatibility, chitosan was widely used in drug delivery, 21 wound healing, 22 antibacterial treatment, 23 food manufacturing, 24,25 biochemical analysis 26 and other elds.…”