Application Of Carbon Quantum Dots Research Articles

Synthesis and application of carbon quantum dots for document security: current status and future outlook

This paper mainly summarizes the research progress of the preparation, modification and application of carbon quantum dots in the field of certificate anti-counterfeiting, and focuses on its application in anti-counterfeiting ink, fluorescent labeling, doping materials, barcode and anti-counterfeiting film. In addition, the article also analyzes the problems and future challenges such as the urgent need to optimize the preparation process of carbon quantum dots, the need for future development in combination with multidisciplinary development, and the damage of the best fluorescence performance conditions to the certificate itself. In general, as a new type of nanomaterial, carbon quantum dots have broad application prospects in the field of document anti-counterfeiting.

Carbon Quantum Dots in Healthcare: A Promising Solution for Sustainable Healthcare and Biomedical Practices

The pursuit of sustainable development refers to meet the present needs while safeguarding the resources for future generations ensuring the well-being of human societies. Nanoscience is contributing significantly to the field of public healthcare by delivering a number of cutting-edge technological applications and products related to healthcare. Carbon quantum dots (CQDs), carbon-based nanomaterials, are gaining recognition for their potential health benefits worldwide. The current study aims to review the applications of CQDs in the biomedical field based on existing literature. The methodology used is the collection of the literature studies from authoritative sources such as Google Scholar, PubMed, and ResearchGate, with keywords ‘Carbon quantum dots in healthcare, biosensing, bioimaging, gene therapy, treatment, and theranostics’. The retrieved literature was comprehensively analyzed to construct the detailed review which suggests that CQDs have demonstrated remarkable potential across various domains, from disease treatment to biosensing, gene delivery, drug delivery, and bioimaging thus helping to achieve the 3rd goal of sustainable development. In addition to CQDs synthesized by chemical processes, natural CQDs developed by green chemistry from natural sources are gaining accreditation due to their evidenced potential health benefits. This article has reviewed the versatile applications of Carbon Quantum Dots (CQDs) in the biomedical field and discussed the possible contributions to achieve sustainable healthcare for the first time, suggesting CQDs as a potential target for future research and development. However, there are some limitations of CQDs including complex surface modification, toxicity, limited clinical translation which requires more attention in order to improve their healthcare applicability.

Fluorescent carbon quantum dots: Synthesis methods, functionalization and biomedical applications

Carbon Quantum Dots (CQDs), a type of carbon material having size less than 10 nm and strong fluorescence is creating a new paradigm in the field of bioimaging and other biomedical applications. Owing to simple and low cost of synthesis, tunable and precise optical properties, high photostability and ease of surface functionalization with biological entities there is a huge potential in the field of CQDs based cell imaging applications. A thorough knowledge and understanding of synthesis methods and optical properties are crucial in translation of CQDs based bioimaging research from research lab to commercial purposes for societal benefit. Different methods of synthesis like electrochemical, laser ablation, microwave radiation, and hydrothermal and optical properties like photoluminescent (PL) property, quantum confinement effect, doping influence on optical properties of CQDs are covered in this review. Surface functionalization agents employed for different bio applications have been reviewed along with the current challenges. The applications of CQDs in bioimaging, biosensing and drug delivery along with the existing challenges and future prospects are discussed.

Recent Advances on Synthesis and Potential Applications of Carbon Quantum Dots

Fluorescent carbon nanoparticles also termed as carbon quantum dots (CQDs) have attracted so much interest when compared to the traditional semiconductor quantum dots due to their applications in chemical sensing, biomedical imaging, nanotechnology, photovoltaics, light-emitting diodes (LEDs), and electrochemistry. Along with their optical features, CQDs have desired properties such as less toxicity, environmentally friendly nature, inexpensive, and simple preparation processes. In addition, CQDs can have their physical and chemical properties controlled by surface passivation and functionalization. This article provides an account of CQDs because of their distinct characteristics and considerable capacity in diverse applications. The article is categorized into various sections that highlight various synthesis methodologies of CQDs with their advantages/disadvantages and their potential applications in sensors, bio-imaging, drug delivery, solar cells, and supercapacitors. The different applications of CQDs can be demonstrated by controlled synthesis methods. We have also discussed gas sensing applications of CQDs briefly and provided a brief overview of osmotic power generation using CQDs for energy applications.

Green Synthesis of Corn Cob Derived Carbon Quantum Dots and Its Applications as Electrolyte Additive for Lithium-Metal Batteries

Carbon Quantum Dots (CQDs) is a progressive type of zero-dimensional material, inherits the benefits of tiny molecules (e.g., fluorophores) and classic semiconductors (e.g., inorganic quantum dots), as well as new features. A novel attempt has been made in synthesizing photo luminescent CQDs using corn cob extract by adopting a hydrothermal approach. The synthesized CQDs were characterized to understand their chemical, structural, and morphological portrayals. The application of CQD as a deposition regulating additive in lithium metal anode batteries has been explored. Lithium/lithium (Li-Li) symmetric cells fabricated using CQD additive loaded with LiPF6 electrolyte displayed small overpotential and relatively good cycling stability when compared to the Li-Li cell without additive. Full cells (Li-NMC) fabricated using Li-NMC cathode, lithium metal anode, and CQD additive loaded electrolyte showed about 10% increment in specific discharge capacity in comparison to the coin cells fabricated using LiPF6 electrolyte, signifying the positive contribution in controlling the dendrite growth.

Control and Application of Carbon Quantum Dots

Control and Application of Carbon Quantum Dots

Quaternized carbon quantum dots with broad-spectrum antibacterial activity for the treatment of wounds infected with mixed bacteria

Bacterial resistance to antibiotics have become one of the most severe threats in global public health, so the development of new-style antimicrobial agents is urgent. In this work, quaternized carbon quantum dots (qCQDs) with broad-spectrum antibacterial activity were synthesized by a simple green “one-pot” method using dimethyl diallyl ammonium chloride and glucose as reaction precursors. The qCQDs displayed satisfactory antibacterial activity against both Gram-positive and gram-negative bacteria. In rat models of wounds infected with mixed bacteria, qCQDs obviously restored the weight of rats, significantly reduced the death of rats from severe infection, and promoted the recovery and healing of infected wounds. Biosafety tests confirmed that qCQDs had no obvious toxic and side effects during the testing stage. The analysis of quantitative proteomics revealed that qCQDs mainly acted on ribosomal proteins in Staphylococcus aureus (Gram-positive bacteria) and significantly down-regulated proteins associated with citrate cycle in Escherichia coli (Gram-negative bacteria). Meanwhile, real-time quantitative PCR confirmed that the variation trend of genes corresponding to the proteins associated with ribosome and citrate cycle was consistent with the proteomic results after treatment of qCQDs, suggesting that qCQDs has a new antibacterial mechanism which is different from the reported carbon quantum dots with antibacterial action. Statement of significanceWith the development of the research on carbon quantum dots, the application of carbon quantum dots in the field of medicine has attracted extensive attention. In this paper, quaternized carbon quantum dots (qCQDs) with antimicrobial activity prepared by specific methods were studied, including antimicrobial spectrum, antimicrobial mechanism and in vivo antimicrobial application. The antimicrobial mechanism of qCQDs was studied by proteomics and RT-qRCR, and the different mechanisms of qCQDs against Gram-positive and Gram-negative bacteria were also found. This study provides a research foundation for the application of carbon quantum dots in antimicrobial field, and also expands the application range of carbon quantum dots in medicine field.

Green carbon dots based ultraviolet photovoltaic window with high transparence to visible light

Since the absorption spectra of carbon quantum dots are mainly concentrated in the ultraviolet region and nearly transparent to visible light, a new concept of ultraviolet photovoltaic window is proposed using carbon quantum dots as a light absorber. The photovoltaic window can generate electricity without affecting indoor lighting and effectively block the entry of ultraviolet light. Cotton fiber as carbon precursor and urea as dopant are used to prepare green N-doped carbon quantum dots with blue fluorescence. Moreover, the amount of dopant and thickness of TiO2 film have a great influence on the power conversion efficiency and transmittance of the photovoltaic window. The best efficiency of the photovoltaic window obtained is 0.614% and its average visible transmittance is also the best (37.2%) among the prepared photovoltaic windows. The construction of ultraviolet photovoltaic window successfully opens up a new application of carbon quantum dots in building-integrated photovoltaics.

Green preparation and application of carbon quantum dots

Carbon quantum dots (CQDs) are a new type of carbon-based zero-dimensional materials. Carbon quantum dots have many advantages such as excellent optical properties, good water solubility, low toxicity, environmental friendliness, wide source of raw materials, low cost, and good biocompatibility. Since the first discovery of carbon quantum dots, a variety of synthetic methods have been developed. This article lists the preparation methods and applications of carbon quantum dots, and discovers a new method for ionic liquids as modifiers, which will play an important role in the future research of carbon quantum dots.

Applications of carbon quantum dots in lubricant additives: a review

Advances in lubricants are vital to the pursuit of energy efficiency and sustainable development. It is well known that the essence of lubricating oil is lubricant additives, especially the friction-reducing and anti-wear additives. Carbon quantum dots (CQDs), a novel zero-dimensional carbon-based nanomaterial, have attained growing expectations in material and chemical sciences because of their extraordinary properties such as low toxicity and environmentally friendly, high chemical and thermal stability, and good designability. Since their discovery, CQDs have shown great potential in many applications including sensors, medicine, photovoltaic devices, biology, and tribology. The latest application of CQDs as the high-performance friction-reducing and anti-wear additives has garnered increasing attention. With the in-depth study, CQDs have gradually exhibited their excellent tribological properties, especially acted as additives in lubricating base oils. This paper has reviewed the progress in the research and development of CQDs-based lubricant additives by introducing lots of successful applications of CQDs-based additives in the present work and then highlighted the friction-reducing and anti-wear property, superiority, as well as the lubrication mechanism of CQDs as an additive, along with some discussion on challenges and perspectives in this significant and promising field. Finally, we offered a series of suggestions for developing the next-generation high-performance CQDs-based lubricant additives. This work presented the carbon quantum dots as the lubricant additives of lubricating base oils.

Enhanced tolerance to salinity stress in grapevine plants through application of carbon quantum dots functionalized by proline

Salinity has destructive impacts in plant production; therefore, application of new approaches such as nanotechnology and plant priming is attracting increasing attention as an innovative means to ameliorate salt stress effects. Considering the unique properties and recorded beneficial influence of carbon quantum dots (CQDs) and proline in plant growth and physiological parameters when applied individually, their conjugation in the form of carbon quantum dot nanoparticles functionalized by proline (Pro-CQDs NPs) could lead to synergistic effects. Accordingly, an experiment was conducted to evaluate the impact of this advanced nanomaterial (Pro-CQDs NPs) as a chemical priming agent, in grapevine plants cv. 'Rasha'. For this purpose, proline, CQDs, and Pro-CQDs NPs at three concentrations (0, 50, and 100 mg L-1) were applied exogenously 48 h prior to salinity stress (0 and 100 mM NaCl) that was imposed for a month. Three days after imposing salt stress, an array of biochemical measurements was recorded, while agronomic and some physiological parameters were noted at the end of the stress period. Results revealed that proline treatment at both concentrations, as well as CQDs and Pro-CQDs NPs at low concentration, positively affected grapevine plants under both non-stress and stress conditions. Specifically, the application of proline at 100 mg L-1 and Pro-CQDs NPs at 50 mg L-1 resulted in optimal performance identifying 50 mg L-1 Pro-CQDs NPs as the optimal treatment. Proline treatment at 100 mg L-1 increased leaf fresh weight (FW) and dry weight (DW); chl a, b, and proline content; SOD activity under both non-stress and stress conditions; Y (II) under salinity and carotenoid content; and CAT activity under control conditions. Pro-CQDs NP treatment at 50 mg L-1 enhanced total phenol, anthocyanin, and Fv/Fo, as well as APX and GP activities under both conditions, while increasing carotenoid, Y (II), Fv/Fo, and CAT activity under salinity. Furthermore, it decreased MDA and H2O2 contents at both conditions and EL and Y (NO) under salt stress. Overall, conjugation of CQDs with proline at 50 mg L-1 resulted in further improving the protective effect of proline application at 100 mg L-1. Therefore, functionalization of NPs with chemical priming agents appears to be an effective means of optimizing plant-priming approaches towards efficient amelioration of abiotic stress-related damage in plants.

Small Body, Big Light: Applications of Carbon Quantum Dots

Small Body, Big Light: Applications of Carbon Quantum Dots

A Perspective on Application of Carbon Quantum Dots in Luminescence Immunoassays.

Quantum dots (QDs) have been established in our daily life, for instance, in display screens and light-harvesting technologies, mainly owing to their peculiar opto-electronic features. However, toxicity of inorganic QDs, such as CdSe, CdTe, and perovskites, limits their applications in biological environments for medical diagnosis and bio-imaging purposes. A new generation of QDs called carbon quantum dots (CQDs) have been progressing rapidly over the past few years. CQDs have become as popular as other carbon-based nanomaterials such as carbon nanotubes (CNTs), due to their ease of preparation, ultra-small size, biocompatibility, and bright luminescence.

Facile preparation of fluorescent carbon quantum dots from denatured sour milk and its multifunctional applications in the fluorometric determination of gold ions, in vitro bioimaging and fluorescent polymer film

In the present study, the multifunctional applications of food waste derived carbon quantum dots (CQD) have been demonstrated. The results obtained from the absorption and fluorescence spectroscopic analysis affirmed the superior photophysical property of the prepared CQD. X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) studies further confirmed the crystallographic phase and surface functional groups present in the CQD. The ultrafine size of the CQD is established from the high-resolution transmission electron microscope (HR-TEM) micrographs with the grain size of 2−4 nm. The excellent fluorescence property of the CQD is utilised to detect trace levels of Au3+ ions by simply mixing aqueous dispersion of CQD with ascorbic acid (AA). The sensing mechanism is based on the reduction of Au3+ to gold nanoparticles (AuNPs) by AA and the subsequent AuNPs induced fluorescence quenching of CQD by synergistic static quenching and inner filter effect. The CQD/AA probe could selectively detect Au3+ ion as low as 0.95 μM. The cytotoxicity of the CQD toward U-251 MG glioblastoma cell revealed that the CQD did not possess any significant cytotoxicity. The application of CQD in bioimaging of cells is ascertained by fluorescence microscopic analysis. Furthermore, fluorescent polymer films were prepared by incorporating CQD within the polymer matrix (poly-vinyl-alcohol).

Application of Carbon Quantum Dots in the Field of Nanosensors

Compared with traditional semiconductor quantum dots, carbon quantum dots show adjustable excitation wavelength and emission wavelength, good stability, weather resistance and light resistance. Moreover, their photoluminescence properties, good biocompatibility and easy surface modification provide a wide application in life sciences and tracer sensing. Therefore, the study of carbon quantum dots will definitely promote the development of materials science, and it will also gain more attention for the carbon material family. Firstly, an “on–off–on” fluorescent phosphorus/nitrogen co-doped carbon dot (PNCD) probe was explored for the determination of Cr(VI) and dopamine resulting from the inner filter effect (IFE). The blue-emitting carbon dots with high quantum yields of 25.47% as well as a narrow size distribution were synthesized by a rapid, convenient route using H3PO4 and ethylenediamine as the precursors without any surface passivation. A wide linear region in the range of 7–70 mM with a detection limit of 0.71 mM was achieved for Cr(VI). Moreover, the proper reductants can weaken the inner filter effect to recover the PNCD fluorescence by converting Cr(VI) into Cr(III). Therefore, the PNCDs/Cr(VI) hybrid could also be used as an “off–on” fluorescent probe for detecting dopamine (DA) with a detection limit of 0.49 mM. Consequently, the PNCDs could serve as a powerful fluorescent bi-sensor for detection of both Cr(VI) and DA in practical applications. Then, a kind of water-soluble P, N, B-co-doped carbon quantum dots (PNBCDs) synthesized using a convenient hydrothermal method exhibit many excellent features, such as strong fluorescence, excitation independent emission, high mono-dispersity, good stability, and excellent water solubility with a fluorescence quantum yield of 21.95%. The as-prepared PNBCDs possessed remarkable selectivity and sensitivity towards curcumin with the linear range of 0–1.5 mmol L-1 and the detection limit for curcumin was 68 nmol L-1 (3s/k). Additionally, the wonderfully reversible and repeatable sensitivity to external temperature makes it possible that the PNBCDs could be used as a biocompatible fluorescent ink and for thermo-sensitive devices.

Facile Preparation of Stable Solid-State Carbon Quantum Dots with Multi-Peak Emission.

Aggregation-caused quenching (ACQ) effect, known as the main cause to restrain solid-state luminescence of carbon quantum dots (CQDs), hinders further application of CQDs in white light-emitting diodes (WLED). Here, a complex of CQDs and phthalimide crystals (CQDs/PC) was prepared through a one-step solvothermal method. CQDs/PC prevented CQDs from touching directly by embedding the CQDs in phthalimide crystal matrix in situ, which effectively reduced the ACQ effect. Furthermore, CQDs/PC exhibited multi-peak fluorescence spectra that span the green, yellow and orange spectral regions. Finally, a WLED fabricated based on CQDs/PC achieved a color-rendering index of 82 and a correlated color temperature of 5430 K. This work provides a quick and effective strategy to apply CQDs to WLED.

Principles, mechanisms, and application of carbon quantum dots in sensors: a review

The mechanism of the CQDs-based sensors.

A carbon-based memristor design for associative learning activities and neuromorphic computing.

Carbon quantum dots (QDs) have attracted significant interest due to their excellent electronic properties and wide application prospects. However, the application of carbon QDs has been rarely reported in memristors. Here, a memristor model with carbon conductive filaments (CFs) is proposed for the first time based on carbon quantum dots. The CF-based devices exhibited excellent resistive switching performance, in particular a narrow range of SET and RESET voltages and good power efficiency and retention properties. These devices could also emulate important biological synapse performances, such as the transition from short-term plasticity (STP) to long-term potentiation (LTP) behaviors, long-term depression (LTD) behavior, and four types of spike-timing-dependent plasticity (STDP) learning rules. Interestingly, Pavlovian associative learning functions were also reliably demonstrated in the memristor device (MD). The digit recognition ability of the MDs was evaluated though a single-layer perceptron model, in which the recognition accuracy of digits reached 92.63% after 250 training iterations. The transmission electron microscopy (TEM) results evidenced that the carbon CF was found in the MD at the "ON" state. Thus, this new carbon CF-based mechanism for memristors provides a new idea for achieving better neuromorphic MDs and applications.

Multifunctional p‐Type Carbon Quantum Dots: a Novel Hole Injection Layer for High‐Performance Perovskite Light‐Emitting Diodes with Significantly Enhanced Stability

AbstractFor metal halide perovskite (MHP)‐based light‐emitting diodes (PeLEDs), effective radiative recombination of the injected holes and electrons within the MHP layer and minimized injection energy barriers at the interfaces between MHP emission layer and charge injection layers are prerequisites for high‐performance and stable PeLEDs. Herein, for the first time, novel p‐type carbon quantum dots (CQDs) are introduced as a hole injection layer in PeLEDs to replace acidic poly(3,4‐ethylenedioxythiophene):poly styrene sulfonate (PEDOT:PSS) layer. The CQDs demonstrate high hole transport mobility and desirable hole injection energy level. Moreover, the carboxyl, amine, and hydroxyl groups on CQDs not only offer a hydrophilic surface for high‐quality perovskite layer growth, but also passivate the perovskite surface defects to suppress the interfacial exciton quenching. Based on the multifunctional p‐type CQDs, high‐performance green CsPbBr3 PeLEDs with a low turn‐on voltage of only 2.8 V, maximum luminance of 25 770 cd m−2, and maximum external quantum efficiency (EQE) of 13.8% are achieved. The PeLEDs also show good operational stability and long‐term environmental stability. The first application of CQDs as a hole injection layer in PeLEDs breaks through the traditional cognition of carbon materials and opens up new pathways for the developments of carbon nanomaterials in optoelectronic devices.

Preparation and application of carbon quantum dots filled hollow mesoporous silica nanospheres

Hollow mesoporous silica and carbon quantum dots play an important role in the field of biological applications. In this study, a nano-scale hollow mesoporous silica nanosphere (HMSN) was used as the main body of a drug transport system, which filled with a small amount of carbon quantum dots. The hollow mesoporous silica structure provides a large specific surface area and cavity structure for efficient drug loading. And the carbon quantum dots could provide good fluorescence for imaging. By filling carbon quantum dots inside of silica nanospheres and in mesopores on the surface, the hollow mesoporous silica nanospheres became fluorescent and could be used as a fluorescent probe. And the potential photothermal effect of the internal carbon quantum dots also makes it possible to achieve controlled drug release through temperature changes.