Photoluminescent Carbon Nanoparticles Research Articles

Supramolecular Chemistry of Carbon-Based Dots Offers Widespread Opportunities.

Carbon dots are an emerging class of nanomaterials that has recently attracted considerable attention for applications that span from biomedicine to energy. These photoluminescent carbon nanoparticles are defined by characteristic sizes of <10 nm, a carbon-based core and various functional groups at their surface. Although the surface groups are widely used to establish non-covalent bonds (through electrostatic interactions, coordinative bonds, and hydrogen bonds) with various other (bio)molecules and polymers, the carbonaceous core could also establish non-covalent bonds (ππ stacking or hydrophobic interactions) with π-extended or apolar compounds. The surface functional groups, in addition, can be modified by various post-synthetic chemical procedures to fine-tune the supramolecular interactions. Ourcontribution categorizes and analyzes the interactions that are commonly used to engineer carbon dots-based materials and discusses how they have allowed preparation of functional assemblies and architectures used for sensing, (bio)imaging, therapeutic applications, catalysis, and devices. Using non-covalent interactions as a bottom-up approach to prepare carbon dots-based assemblies and composites can exploit the unique features of supramolecular chemistry, which include adaptability, tunability, and stimuli-responsiveness due to the dynamic nature of the non-covalent interactions. It is expected that focusing on the various supramolecular possibilities will influence the future development of this class of nanomaterials.

Solvent-free synthesis of photoluminescent carbon nanoparticles from lignin-derived monomers as feedstock

ABSTRACT Photoluminescent carbon nanoparticles (CNPs), such as carbon dots (CDs), have attracted much attention owing to a unique set of properties, like high and tunable fluorescence. In this way, the use of carbon-rich lignin has been demonstrated to be a sustainable approach to producing a broad range of photoluminescent CNPs. However, the valorization of this complex polyphenol is limited when it comes to green and efficient ways of conversion. In addition, the existing solvothermal approaches using lignin often result in CDs with low photoluminescence, while flammable and/or toxic solvents are employed. Here, we depolymerized technical lignins, i.e. kraft and soda, through electroreductive cleavage in two different sustainable media: deep eutectic solvent and levulinic acid. After depolymerization, lignin-derived monomers were generated, with a predominance of aryl ether and phenolic groups, which were further combined with 1,2-Phenylenediamine to produce N-doped CNPs in a solvent-free approach. Photoluminescent CNPs with varied sizes were generated (5–50 nm), which presented a wide photoluminescence emission, from blue to red, depending on solvent polarity. These results demonstrate a feasible and sustainable route for the solvent-free synthesis of photoluminescent CNPs using lignin-derived monomers as carbon source, which may find applications in a wide range of fields.

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications.

Photoluminescent carbon nanoparticles, or carbon dots, are an emerging class of materials that has recently attracted considerable attention for biomedical and energy applications. They are defined by characteristic sizes of <10 nm, a carbon-based core and the possibility to add various functional groups at their surface for targeted applications. These nanomaterials possess many interesting physicochemical and optical properties, which include tunable light emission, dispersibility and low toxicity. In this Review, we categorize how chemical tools impact the properties of carbon dots. We look for pre- and postsynthetic approaches for the preparation of carbon dots and their derivatives or composites. We then showcase examples to correlate structure, composition and function and use them to discuss the future development of this class of nanomaterials.

Quantum dots and photodynamic therapy in COVID ‐19 treatment

Viral diseases are regarded as a global burden. The eradication of viral diseases is always a challenging task in medical research due to the high infectivity and mutation capability of the virus. The ongoing COVID‐19 pandemic is still not under control even after several months of the first reported case and global spread. In the pursuit of a promising strategy, carbon dots could be considered as potential nanostructure against this viral pandemic. Carbon dots are photoluminescent carbon nanoparticles, smaller than 10 nm in dimension with a very attractive photostable and biocompatible properties which can be surfaced modified or functionalized. These photoluminescent tiny particles have captured much attention owing to their functionalization property and biocompatibility. Photodynamic therapy (PDT) is a technique that is widely used in cancer treatment and against various microbes. In this technique, a light‐induced photosensitizer generates reactive oxygen species (ROS), ultimately killing the target cells. Considering these facts, an attempt has been made to review the current literature on viral inactivation using PDT approach. Accordingly, the mechanism of PDT action has been discussed, along with an update on the use of various photosensitizers (PSs) and nanoparticles. The capsid proteins and nucleic acid (RNA) of SARS‐CoV‐2 can be a possible target for PDT.

Exploring the Potential of Carbon Dots to Combat COVID-19.

Viral diseases are considered as a global burden. The eradication of viral diseases is always a challenging task in medical research due to the high infectivity and mutation capability of the virus. The ongoing COVID-19 pandemic is still not under control even after several months of the first reported case and global spread. Neither a specific drug nor a vaccine is available for public use yet. In the pursuit of a promising strategy, carbon dots could be considered as potential nanostructure against this viral pandemic. This review explores the possibility of carbon nano-dots to combat COVID-19 based on some reported studies. Carbon dots are photoluminescent carbon nanoparticles, smaller than 10 nm in dimension with a very attractive photostable and biocompatible properties which can be surfaced modified or functionalized. These photoluminescent tiny particles have captured much attention owing to their functionalization property and biocompatibility. In response to this pandemic outbreak, this review attempts to summarize the potential use of carbon dots in antiviral therapy with particular emphasis on their probable role in the battlefront against COVID-19 including their possible biosensing applications.

Nitrogen-Bearing Carbon Nanoparticles by Pyrolytic Decomposition of Piperazine Citrate Macromolecules for Cellular Imaging.

In this work, highly photoluminescent carbon nanoparticles (CNPs) are fabricated by pyrolytic decomposition of piperazine citrate at high pressure and high temperature. Piperazine serves as a hydrolytic, surface-passivating, and N-doping agent, facilitating the formation of a photopolymer. The as-synthesized CNPs, without any surface protection/passivation, exhibit excellent photolumi-nescence and a maximum quantum yield of 84%. The average particle size of the N-doped CNPs is 0.89±0.05 nm. In addition, the N-doped CNPs exhibit uniform diameters and nearly spherical shapes. The X-ray photoelectron spectroscopy results reveal that the CNPs are composed of carbon (64.4 wt%), oxygen (18.5 wt%), and nitrogen (17.1 wt%), indicating the presence of nitrogen-doped and carbon-rich moieties in the CNPs. Notably, the CNPs purified by the procedure developed in this work exhibit more stable luminescence properties than those purified with the conventional dialysis membrane. In addition, the potential application of the CNPs as fluorescent bioimaging probes, which offer a broad dosing window and exhibit multicolor emission, is investigated by directly cultur-ing A549 cells with the CNPs. The results reveal that the CNPs exhibit not only exceptional optical stability, but also outstanding biocompatibility and cell labeling capability. After incubating the A549 cells with CNPs, the CNPs are confined in perinuclear vacuole-similar shapes with a granulated form in cytoplasm preserving the nucleus. Notably, no significant morphological deterioration such as nuclear contraction is detected.

An environmental evaluation of carbonaceous aerosols in PM10 at micro- and nano-scale levels reveals the formation of carbon nanodots.

Carbonaceous aerosols play significant roles in air quality and the climate; their oxidation at the nano-scale level may possibly increase the reactivity and toxicity of atmospheric particulates. In the present study, a laboratory experiment on the atmospheric carbonaceous aerosol was done by using H2O2 as an oxidizing agent. An extensive study made with advanced analytical tools revealed the formation of photoluminescent carbon nanoparticles (carbon nanodots) in the carbonaceous aerosol. The carbon nanoparticles are mostly at the sp2 hybridization state and contain various surface functional groups such as carboxyl and carbonyl groups. The properties of these carbon nanoparticles resemble the engineered carbon nanoparticles such as carbon dots (CDs). The carbon nanoparticles, mainly less than 10nm, are composed of carbon nanocrystals containing a few other elements such as Ca and Fe. Fluorescence spectroscopy revealed the characteristic excitation-dependent emission spectra of blue fluorescent carbon nanoparticles. The results indicate the presence of characteristic carbon nanoparticles in the carbonaceous aerosol in PM10, opening a new road for predicting environmental processes occurring in the atmospheric environment.

ChemInform Abstract: Green and Size‐Controllable Synthesis of Photoluminescent Carbon Nanoparticles from Waste Plastic Bags.

AbstractPhotoluminescent carbon nanoparticles (CNP) are prepared by size‐controllable hydrothermal treatment (autoclave, 180 °C, 12 h) of various waste plastic bags in highly diluted H2O2 solutions (≤5.0 wt%) involving oxidative degradation, carbonization, and passivation followed by dialysis (molecular weight cut‐off: 1,000 Da) and freeze‐drying of the obtained solution.

Light-induced synthesis of photoluminescent carbon nanoparticles for Fe3+ sensing and photocatalytic hydrogen evolution

A new method to produce multifunctional CNPs was developed by a light-induced process.

One-pot solvothermal synthesis of highly photoluminescent carbon nanoparticles and their photocatalytic application

Luminescent carbon nanoparticles (CNPs) had shown great impact on bioimaging and environmental applications recently. Here an inexpensive but practical solovethermal method is developed to prepare CNPs using tartaric acid and ammoniumoxalate as starting materials in one-pot. This approach allows large-scale production of aqueous CNPs dispersions without any post-treatment process. The product CNPs have amorphous structures, with diameter of about 10–30nm, exhibit an excitation-independent photoluminescence (PL) behavior. Meanwhile, CNPs showed UV-light sensitive photocatalytic activity for methylene blue (MB) degradation, indicating CNPs potential applications in environment or energy areas.

Photoluminescent carbon soot particles derived from controlled combustion of camphor for superhydrophobic applications

The present perspective presents a novel platform for the synthesis of catalyst free photoluminescent carbon nanoparticles derived from the combustion of camphor in a single step flame process. The soot particles were investigated using Fourier transformation infrared spectroscopy, thermogravimetry, Raman, transmission emission microscopy, X-ray diffraction, UV and photoluminescent spectroscopy. The soot particles exhibited a diamond-like carbon nanostructure, with the presence of hydrophobic functional groups imparting superhydrophobic characteristics. The camphor soot particles revealed the presence of highly graphitized amorphous carbon, which was confirmed by the appearance of G, D1 D2, D3 and D4 bands in the Raman spectra. Photoluminescence of the soot particles was observed when soot particles were excited at λmax. A red shift was clearly noted in the UV spectrum of the soot in different solvents. The agglomeration of camphor soot particles was discussed by measuring the fractal dimensions (Df) of the particles. Combustion of soot particles occurs at 450 °C, approx. 100 °C lower than that of graphene. In-depth investigations suggest the use of these photoluminescent camphor soot particles for superhydrophobic coating applications.

Green and size-controllable synthesis of photoluminescent carbon nanoparticles from waste plastic bags

Hydrothermal treatment of various waste plastic bags in low-concentration H2O2 solutions for green and size-controllable synthesis of photoluminescent carbon nanoparticles.

Facile and green synthesis of photoluminescent carbon nanoparticles for cellular imaging

Here, a simple, green, and economic method was developed for the synthesis of fluorescent carbon nanoparticles (CPs) by one-step hydrothermal treatment of grape juice, without any additives (e.g. salts, acids, bases, and organic solvents). The as-prepared CPs showed bright blue fluorescence under the irradiation of UV light, with a high quantum yield of 13.5%, good water solubility, excellent stability, and low toxicity, which can be used as an excellent fluorescent probe for cellular imaging.

Carbon Dots Prepared by Hydrothermal Treatment of Dopamine as an Effective Fluorescent Sensing Platform for the Label‐Free Detection of Iron(III) Ions and Dopamine

A facile, economic and green one-step hydrothermal synthesis route using dopamine as source towards photoluminescent carbon nanoparticles (CNPs) is proposed. The as-prepared CNPs have an average size about 3.8 nm. The emission spectra of the CNPs are broad, ranging from approximately 380 (purple) to approximately 525 nm (green), depending on the excitation wavelengths. Due to the favorable optical properties, the CNPs can readily enter into A549 cells and has been used for multicolor biolabeling and bioimaging. Most importantly, the as-prepared CNPs contain distinctive catechol groups on their surfaces. Due to the special response of catechol groups to Fe(3+) ions, we further demonstrate that such wholly new CNPs can serve as a very effective fluorescent sensing platform for label-free sensitive and selective detection of Fe(3+) ions and dopamine with a detection limit as low as 0.32 μM and 68 nM, respectively. The new "mix-and-detect" strategy is simple, green, and exhibits high sensitivity and selectivity. The present method was also applied to the determination of Fe(3+) ions in real water samples and dopamine in human urine and serum samples successfully.

Synthesis of photoluminescent carbon nanoparticles from graphite

Photoluminescent carbon nanoparticles (CNPs) with diameters ranging from 1.5 to 6.5 nm were synthesized from raw graphite without surface passivation. The photoluminescent (PL) emission spectra illustrate that both excitation wavelength and solution pH can significantly influence the maximum emission wavelength and PL intensity of the CNP solution. As the excitation wavelength decreases and solution pH increases, a blue shift in the maximum PL emission wavelength occurs.

The production of pH-sensitive photoluminescent carbon nanoparticles by the carbonization of polyethylenimine and their use for bioimaging

A cationic branched polyelectrolyte of large molecular weight, i.e., polyethylenimine (PEI) of 25,000Da, was used as both a carbon source and a passivating agent to prepare photoluminescent carbon nanoparticles (CNPs) in one step. In contrast to the previously reported pH-insensitive CNPs, these CNPs have a distinct pH-sensitive feature that gives them the potential to serve as a proton sensor in monitoring cell metabolization process with proton release. When incubated with HeLa cells, the CNPs could readily penetrate the cell membrane and exhibit low cytotoxicity and favorable biocompatibility. The CNPs have been used for HeLa cell imaging.

Photoluminescent carbon nanoparticles produced by confined combustion of aromatic compounds

We report new photoluminescent carbon nanoparticles having an average particle size of 50 nm. When dispersed in chloroform and excited with 325 nm wavelength, the solution showed strong photoluminescence at 475 nm with 12–13% quantum yield. A well dispersed photoluminescent solution can also be prepared with ethanol, xylene or hexane using the nanoparticles. The nanoparticles were prepared by a simple confined combustion of an aromatic compound such as benzene, toluene, xylene or a mixture thereof in air.