Nitrogen-doped carbon quantum dots as fluorescent nanosensor for selective determination and cellular imaging of ClO. Spectrochim Acta A Mol Biomol Spectrosc 2022;271:120941. [PMID: 35114635 DOI: 10.1016/j.saa.2022.120941]

Carbon dots-based dual-emission ratiometric fluorescent sensors for fluorescence and visual detection of hypochlorite and Cu2

Carbon dots (CDs) with blue emission were synthesized by solvothermal method using hydroquinone and 5-aminoisphthalic acid as precursors. The strong oxidation of ClO- caused the fluorescence quenching of CDs at 405 nm, and synchronously generated a new emission peak at 500 nm. Furthermore, upon the addition of Cu2+ to CDs-ClO- system, the green fluorescence at 500 nm was quenched, while the blue emission at 405 nm remained unchanged, due to the complexation between Cu2+ and the amino group on the CDs surface. Meanwhile, the fluorescence color of system changed from blue to bright green and then to dark blue by sequentially increasing the concentrations of ClO- and Cu2+. The fluorescence signal of F500/F405 exhibited a linear relationship with the concentration of ClO- and Cu2+ in a certain range, respectively. Thus, a ratiometric fluorescence sensor based on the obtained CDs were developed to sequentially detect ClO- and Cu2+ with detection limits of 0.40 μM and 0.31 μM, respectively. Additionally, the CDs were mixed with polyvinyl alcohol hydrogel to form test strips, which were successfully used for visual detection of ClO- and Cu2+. Satisfactory results were also obtained in the analysis of ClO- and Cu2+ in actual water samples.

Carbon Nanomaterial Fluorescent Probes and Their Biological Applications

Fluorescent carbon nanomaterials have broadly useful chemical and photophysical attributes that are conducive to applications in biology. In this review, we focus on materials whose photophysics allow for the use of these materials in biomedical and environmental applications, with emphasis on imaging, biosensing, and cargo delivery. The review focuses primarily on graphitic carbon nanomaterials including graphene and its derivatives, carbon nanotubes, as well as carbon dots and carbon nanohoops. Recent advances in and future prospects of these fields are discussed at depth, and where appropriate, references to reviews pertaining to older literature are provided.

Zero-Dimensional Carbon Nanomaterials for Fluorescent Sensing and Imaging

Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.

Carbon dots as specific fluorescent sensors for Hg2+ and glutathione imaging

Nitrogen-doped carbon dots (NCDs) have been constructed in which coal washing wastewater is used as carbon precursor, tryptophan is added for nitrogen doping and surface functional together with polyethylene glycol. The nitrogen doping and surface functional with electron rich groups resulted in excellent fluorescent properties regarding stability, reversibility, printability with high quantum yield which not only enable the NCDs as fluorescent ink for advanced message encryption, but also realize specific on-off-on fluorescent sensing of Hg2+ and GSH as solution, hydrogel and filter paper sensors. The NCDs had a linear range of 0.01-100 μM and a detection limit of 6.27 nM (RSD 0.33%) for Hg2+ and the NCDs@Hg2+ had a linear range of 0.01-60 μM and a detection limit of 3.53 nM (RSD 1.53%) for GSH in sensing studies with aqueous solutions. In addition, with the low cytotoxicity and good biocompatibility NCDs have been successfully used for imaging Hg2+ and GSH in living MG-63 cells. The presented NCDs recycle waste coal washing water into worthwhile material which can be implemented as promising anti-counterfeiting and message encryption candidates as well as effective Hg2+ and GSH sensing, tracking and removing tools in complicated environmental and biological systems.

Preparation of novel fluorescent probe based on carbon dots for sensing and imaging Fe(III) and pyrophosphate in cells and zebrafish

Ferric ions (Fe³⁺) and pyrophosphate anions (PPi) are involved in many physiological processes and play important roles in biological systems. The abnormal level of Fe³⁺ and PPi will cause serious damage to the environment and life. At present, the application of such probes in life, especially in vivo, is still very scarce. So, the development of a fluorescent probe to simultaneously detect Fe³⁺ and PPi has great significance to the health of the environment and organisms. Herein, nitrogen-doped carbon quantum dots (N-CDs) were synthesized via solvothermal treatment, using biuret and citric acid as precursors. The synthesized N-CDs showed highly selective and sensitive detection of Fe³⁺ through a photoluminescence quenching effect. The fluorescence of N-CDs quenched by Fe³⁺ could be restored with PPi, rendering the N-CDs/Fe³⁺ sensor promising for PPi detection ('OFF-ON'). The linear ranges of detection for Fe³⁺ and PPi were 3-30 and 2-12 μM, and the limits of detection were 2.71 and 1.12 μM, respectively. The practical applications of N-CDs were tested using tap water samples. Furthermore, N-CDs can be used for the detection and imaging of Fe³⁺ and PPi in HeLa cells and zebrafish owing to their excellent optical properties.