Preparation of highly crystalline nitrogen-doped carbon dots and their application in sequential fluorescent detection of Fe3+ and ascorbic acid

Nitrogen-Doped Carbon Quantum Dots from Poly(ethyleneimine) for Optical Dual-Mode Determination of Cu2+ and l-Cysteine and Their Logic Gate Operation

“…Similar to the detection of Cu 2+ , the steady-state fluorescence and UV–vis absorption of PQDs responding to Fe 3+ also reached a constant value within 1 min (Figure S3A in the Supporting Information). Upon the addition of Fe 3+ to the PQDs solution, the fluorescence intensity of PQDs decreased gradually (Figure S3B in the Supporting Information), which was attributed to the formation of a chelate complex between Fe 3+ and the −OH on the surface of PQDs and the electron transfer from PQDs to Fe 3+ . , Interestingly, the addition of Fe 3+ to the PQDs solution cannot lead to the change of the solution color. Meanwhile, the maximum absorption wavelength of PQD-Fe 3+ in Figure S3C is different from that of the PQD-Cu 2+ system (272 and 630 nm).…”

Sustainable and Green Synthesis of Waste-Biomass-Derived Carbon Dots for Parallel and Semi-Quantitative Visual Detection of Cr(VI) and Fe3+

“…By contrast, only a few studies have reported CD-based multifunctional sensors for the multi-mode sensing of two or more types of analytes [29][30][31][32]. For instance, Wang's group utilized the "green" CDs synthetized by hydrothermal treatment of chitosan and tartaric acid for the continuous fluorescent determination of Fe 3+ and L-ascorbic acid [33]. However, the majority of the reported CD-based multifunctional fluorescent sensors followed a tandem sensing process [34], which meant that the selective response to the latter analyte could not be achieved without the prerequisite of successful sensing for the former analyte.…”

Highly crystalline N and S co-doped carbon dots as a selective turn off–on sensor for Cr(vi) and ascorbic acid and a turn off sensor for metanil yellow

“…The hexavalent Cr(VI) has been reported to pose a more significant threat to human health because of its high toxicity, water-solubility, carcinogenesis, teratogenicity, and mutagenicity 16 Even though the World Health Organization (WHO) has set a consumption limit of 0.05 µg/ml for Cr(VI), there is still a lack of studies to figure out the minimum amount of Cr(VI), which could lead to disease when ingested 17 have all reported N and sulfur co-doped carbon dots as a selective sensor for Cr(VI) ions 1819,20 Ascorbic acid, commonly known as Vitamin C, plays a vital role in maintaining healthy physiological functions 21 However, as it is known that the human body cannot synthesize ascorbic acid, it has been acquired from food, and drugs 22 The deficiency of ascorbic acid has been related to many diseases such as cancer, cardiovascular diseases, and Parkinson's disease 23 However, numerous methods for detecting ascorbic acid have been reported in the literature, such as HPLC 24 , UV-Vis spectroscopy 25 electrochemical process 26 and fluorescence 27282930 Amongst all methods, fluorescence methods are highly desirable because of their high sensitivity, high selectivity, simplicity, and convenience 31 . Metanil yellow is banned toxic azo dye, which has been added to turmeric powder to mimic the appearance of curcumin 32 Metanil yellow has been cited in the literature to cause testicular damage in guinea pigs, rats, and mice; it is reported to induce hematological changes and affect the synthesis of DNA 33 Therefore, the need to detect Metanil yellow in food is of paramount importance.…”