Blue Luminescent Carbon Dots Research Articles

Iron Ion (Fe3+) Detection of Blue Luminescent Carbon Dots Derived from Wasted Paper Cup

Iron Ion (Fe³⁺) Detection of Blue Luminescent Carbon Dots Derived from Wasted Paper Cup

Fe3+-induced luminescence quenching in carbon dots - mechanism unveiled.

Carbon dot (CD)-based fluorimetric sensors have attracted immense attention for the detection of metal ions. Among the available works in this direction, more than 70% of the studies reported the detection of Fe3+ through luminescence quenching. Ferric ions are significant species from environmental and biological point of view. Excited-state electron transfer from carbon dots to ferric ions is suggested as the reason for the luminescence quenching. However, to date, no solid proof was provided to demonstrate this electron transfer process. Herein, N-doped blue luminescent carbon dots prepared via hydrothermal carbonization are used to demonstrate the exact mechanism operating in the above-mentioned detection strategy. The carbon dots possessed an average size of 4.9 nm, and exhibited good aqueous solubility as well as an excitation wavelength-dependent emission. Fe3+-mediated luminescence quenching was quantitatively achieved at the micromolar level, with a detection limit of 1.426 μM. The CD-mediated reduction of ferric ions is confirmed by spectral analysis. Fe3+-induced luminescence quenching was partially restored in the presence of ascorbic acid, enabling the sub-micromolar level monitoring of this analyte, with the lowest detection amount of 276 nM. Turnbull's blue method is adopted for confirming the reducing role of ascorbic acid, which eventually increased the luminescence of the system, evoking a turn-on response.

A fluorescence probe based on blue luminescent carbon dots for sensing Fe3+ in plants

Blue fluorescent carbon dots were synthesized via a hydrothermal method using glutathione and sodium citrate, and a carbon dot-based sensing platform was constructed to realize in vivo sensing of Fe3+ distribution in plant species.

One arrow two hawk approach for simultaneous detection and photoreduction of toxic hexavalent chromium by N, S-co-doped carbon dots

The pervasive presence of hexavalent chromium (Cr(VI)) ions in water, coupled with their highly toxic and carcinogenic nature, poses a serious threat to aquatic ecosystems and human well-being. Hence, to mitigate this concern, blue luminescent carbon dots (CG-CDs) have been synthesized using readily available low-cost precursors, namely citric acid and glutathione, which exhibited remarkable capabilities for both sensing as well as photoreduction of toxic Cr(VI). Their selectivity and sensitivity are truly remarkable, with a detection limit as low as 78 nM showing no significant interference with other ions. In addition to its application in fluorometric detection, CG-CDs also showed impressive photocatalytic properties for the reduction of hazardous Cr(VI) to less toxic Cr(III) ions when exposed to sunlight, achieving ∼ 99 % conversion of 25 ppm Cr(VI) within a mere 30 min at pH 4 using 1 mg/mL of CG-CDs. Additionally, the effective sensing and reduction ability of CG-CDs towards Cr(VI) in real water samples makes them versatile material for detecting and photoreducing Cr(VI) in aqueous environments.

Preparing Colour-Tunable Tannic Acid-Based Carbon Dots by Changing the pH Value of the Reaction System.

Biomass carbon dots (CDs) have the characteristics of being green, nontoxic, inexpensive, and simple to prepare, and they can be used in luminescence-related fields. In this study, red, green, and blue luminescent CDs were synthesised by a simple hydrothermal method under alkaline, neutral, and acidic conditions using TA as carbon source and o-phthalaldehyde as blend. The unique optical properties of these CDs are due to the differences in their degrees of conjugation, which can be controlled by the pH value of the reaction system. These three kinds of biomass CDs have good applications in light-emitting diodes (LEDs). By mixing biomass CDs with epoxy resin, warm, and cold white LEDs with Commission Internationale de l’Elcairage (CIE) coordinates (0.35, 0.36) were successfully constructed on extremely stable multicolour CDs. This study shows that these biomass CDs are a promising material for white LED lighting.

Carbon Dots from Coffee Grounds: Synthesis, Characterization, and Detection of Noxious Nitroanilines

Coffee ground (CG) waste is generated in huge amounts all over the world, constituting a serious environmental issue owing to its low biodegradability. Therefore, processes that simultaneously aim for its valorization while reducing its environmental impact are in great demand. In the current approach, blue luminescent carbon dots (C-dots) were produced in good chemical yields from CGs following hydrothermal carbonization methods under an extended set of reaction parameters. The remarkable fluorescent properties of the synthesized C-dots (quantum yields up to 0.18) allied to their excellent water dispersibility and photostability prompted their use for the first time as sensing elements for detection of noxious nitroanilines (NAs) in aqueous media. Very high levels of NA detection were achieved (e.g., limit of detection of 68 ppb for p-nitroaniline), being the regioisomeric selectivity attributed to its higher hyperpolarizability and dipole moment. Through ground–state and time-resolved fluorescence assays, a static fluorescence quenching mechanism was established. 1H NMR titration data also strongly suggested the formation of ground–state complexes between C-dots and NAs.

Fabrication of carbon dots@hierarchical mesoporous ZIF-8 for simultaneous ratiometric fluorescence detection and removal of tetracycline antibiotics

Excessive residues of tetracycline antibiotics (TCs) are very harmful to the ecosystems and human health, thus it is urgent to establish an effective method for both detection and removal of TCs. Herein, the blue luminescent carbon dots (CDs) were synthesized and modified into a hierarchical mesoporous zeolitic imidazolate framework-8 (HZIF-8) which prepared using hydrogel as template to form CDs@HZIF-8 complex. The blue fluorescence of CDs@HZIF-8 at 440 nm was quenched by TCs through internal filtering effect (IFE), meanwhile, the interaction between TCs and Zn2+ led to a significant conformational change of TCs, which enhanced the fluorescence at 536 nm. Based on the reverse change of two fluorescence signals (F536/F440), a ratiometric fluorescence sensor was constructed for the detection of TCs. It is worth mentioning that, thanks to the hierarchical porous structure of CDs@HZIF-8, sufficient space is provided for TCs enrichment in the pores and full contact with the skeleton, which improves the adsorption capacity of TCs and significantly enhances the sensitivity of TCs detection. The detection limits of tetracycline (TC), oxytetracycline (OTC) and doxycycline (DOX) were 6.56 nM, 29.46 nM, and 30.58 nM, respectively. Additionally, the rational design method was successfully applied to detect TCs in milk samples.

Facile synthesis of nitrogen doped carbon dots from waste biomass: Potential optical and biomedical applications

Abstract We report a facile, one-pot hydrothermal synthesis of surface passivated, nitrogen doped carbon dots (N-CDs) from jackfruit peel and tamarind peel precursors. The synthesized N-CDs emit strong excitation dependent fluorescence in the blue region. The samples illustrate exciting quantum confined optical properties. Graphitization of N-CDs is identified by X-ray diffraction. Surface functionalization is confirmed by FT-IR studies whereas nitrogen doping by X-ray photoelectron spectroscopy. The average size of synthesized N-CDs estimated from transmission electron images is 6.4 nm and 5.3 nm for jackfruit peel and tamarind peel precursors respectively. Quantum yield of N-CDs from jackfruit peel (13.04%) is higher than that from tamarind peel (6.13%). Appreciable anti-cancerous activity of the as-prepared carbon dots could be detected with DLA tumour cells extracted from mice. The work proposes an innovative design to yield blue luminescent carbon dots with high quantum yield from biowaste, providing a green and sustainable alternative to traditional carbon sources.

Heteroatom doped blue luminescent carbon dots as a nano-probe for targeted cell labeling and anticancer drug delivery vehicle

Herein, a simple and efficient method to fabricate nitrogen and sulphur doped photoluminescent carbon dots (C-dots) has been judiciously developed for targeting cancer cells. Advancement in newfangled imaging tool for cancer cells is a vital and highly trustworthy strategy for cancer therapy. The fluorescent C-dots prepared from κ-carrageenan and folic acid can serve as an efficient cargo for cancer cell labeling expressing the folate receptor on their surface. The prepared C-dots unveiled good water solubility, excellent photostability, and biocompatibility. The C-dots played the role of nano-vehicle for anticancer drug capecitabine under different pH environments. Also, C-dots were applied as invisible marker and finger print recovery applications. The folate receptor in C-dots led to amazing targetability of cancer cells and which embraces a great promise in biomedical studies.

Carbon dots embedded metal-organic framework@molecularly imprinted nanoparticles for highly sensitive and selective detection of quercetin

A facile and efficient one-pot approach for the synthesis of carbon dots embedded metal-organic framework@molecularly imprinted polymer nanoparticles (CDs@MOF@MIP), which can be used for highly selective and sensitive optosensing of quercetin (QCT), is reported herein for the first time. Metal-organic frameworks (MOFs) with high specific surface area and porosity were first prepared via a room-temperature reaction and used as a matrix to construct MOF-based sensor. Then, highly blue luminescent carbon dots (CDs) were introduced to act as signal transducer that can sense the bonding interactions between the developed sensor and the target molecules and further transduce them to the detectable fluorescence signals. Final, through a surface molecular imprinting process, the resulting CDs@MOF@MIP was obtained. The CDs@MOF@MIP not only exhibited higher selectivity and sensitivity toward target molecular compared to carbon dots embedded metal-organic framework @non-imprinted polymer (CDs@MOF@NIP), but also showed faster reaction rate than CDs-embedded molecularly imprinted polymer (CDs@MIP) derived from the introduction of porous MOF and the optical detection. This proposed sensor was employed to sense trace QCT, and its fluorescence presented a well linear decline with the increasing concentration of QCT from 0 μM to 50.0 μM with a limit of detection of 2.9 nM (S/N = 3), and the precision for eleven replicate detections of 0.5 μM QCT was 1.9%. This developed CDs@MOF@MIP sensor was also used to determine QCT content in real Ginkgo biloba extract capsules with satisfactory performance, and the results were correlated well with those obtained using high performance liquid chromatography.

Influence of surface chemistry on optical, chemical and electronic properties of blue luminescent carbon dots.

Carbon dots have attracted much attention due to their unique optical, chemical and electronic properties enabling a wide range of applications. The properties of carbon dots can be effectively adjusted through modifying their chemical composition. However, a major challenge remains in understanding the core and surface contributions to optical and electronic transitions. Here, three blue luminescent carbon dots with carboxyl, amino and hydroxyl groups were comprehensively characterized by UV-vis absorption and emission spectroscopy, synchrotron-based X-ray spectroscopy, and infrared spectroscopy. The influence of the surface functionality on their fluorescence was probed by pH-dependent photoluminescence measurements. Moreover, the hydrogen bonding interactions between water and the surface groups of carbon dots were characterized by infrared spectroscopy. Our results show that both core and surface electronic states of blue luminescent carbon dots contribute to electronic acceptor levels while the chemical nature of the surface groups determines the hydrogen bonding behavior of the carbon dots. This comprehensive spectroscopic study demonstrates that the surface chemistry has a profound influence on the electronic configuration and surface-water interaction of carbon dots, thus affecting their photoluminescence properties.

Orange, yellow and blue luminescent carbon dots controlled by surface state for multicolor cellular imaging, light emission and illumination.

Three kinds of carbon dots (CDs) with different photoluminescence (PL) (blue, yellow or orange) were synthesized by microwave heating. They display wavelength-independent excitation wavelengths (in the range from 444 to 574nm), similar average particle size (from 3.7 to 4.2nm), and fluorescence lifetimes (from 2.7 to 3.1ns). Color and quantum yields (from 8 to 45% in ethanol) are related to the oxidation degree and the number of N-functional groups on their surface. The CDs are shown to be viable nanoprobes for multicolor imaging of cells. Three composite phosphors were obtained by coating the various CDs on starch particle. The resulting nanomaterials emit solid-state fluorescence with a quantum yield of ≥16%. They were used to fabricate luminescent blocks and light-emitting diodes with controllable color temperature. Graphical abstract (a) The synthesis process of the three carbon dots (CDs). The application in cell imaging (b), starch/CD phosphors (c), starch/CD phosphors-based luminescent blocks (d) and light-emitting diodes (e). (λex: excitation wavelength).

Encapsulation and protection of carbon dots within MCM-41 material

The effective encapsulation of Carbon Dots (CDs) within spherical-like MCM-41 nanoparticles is reported in this work, using a simple, low cost synthetic procedure, here focusing on blue luminescent CDs. CDs of 2 nm average size, with strong photoluminescence, are embedded into MCM-41 nanoparticles during the sol-gel procedure, using tetrathylorthosilicate as the precursor for the glass structure, whereas a cationic surfactant is used as the structure directing agent under basic conditions. The white powder of the final hybrid material showed long term, stable photoluminescence due to the presence of the CDs, indicating the protective character of the silica matrix. Most importantly, it is reported that the photoluminescence of the final hybrid material is not significantly affected by a thermal treatment at 550 °C. The transparent nature of the MCM-41, allows loading this type of mesoporous materials with CDs, thus, providing some new key composite photoluminescent materials for energy and other related applications.

One-Pot Hydrothermal Synthesis of Carbon Dots with Efficient Up- and Down-Converted Photoluminescence for the Sensitive Detection of Morin in a Dual-Readout Assay

Blue luminescent carbon dots (CDs) with a high photoluminescence (PL) quantum yield (48.3 ± 5.3%) were prepared by the one-pot hydrothermal reaction of citric acid with poly(ethylenimine) (PEI). The CDs display bright PL, narrow emission spectra, pH-dependent PL intensity, high photostability, and up-converted luminescence. The CDs exhibit a quenching of both down- and up-conversion PL in the presence of morin and thus serve as useful probes for morin detection. Both down- and up-conversion measurements allow the quantification of concentrations from 0 to 300 μmol/L with a detection limit of 0.6 μmol/L, and this dual-mode detection increases the reliability of the measurement. The proposed method of determination is simple, sensitive, and cost-effective, with potential applications in clinical and biochemical assays.

Facile heat reflux synthesis of blue luminescent carbon dots as optical nanoprobes for cellular imaging

Carbon dots with good temperature-sensitive photoluminescence are facilely synthesized and their luminescence properties and cellular imaging applications are investigated.