摘要:Carbon dots(CDs) may be useful in many fields due to its excellent optical properties, high biocompatibility and low toxicity. The knowledge of its photoluminescence(PL) mechanism has been extensively studied, which is of great significance for guiding the synthesis and popularization of CDs with adjustable PL emission. However, the internal mechanism of PL emission is still unclear, and due to the difference in particle structure, a unified mechanism has not yet been found. This review summarizes a new CDs classification based on the analysis of structural and performance characteristics, called carbonized polymer dots(CPDs). Three PL mechanisms related to structural differences are summarized: internal factors dominate emission(including conjugation effects, surface state and synergistic effects), external factors dominate emission(including molecular state and environmental effects), and cross-linking-emissions. The optical application of CDs is also briefly introduced. Finally, the prospects for research into PL mechanisms are discussed, noting the remaining challenges and directions for future work.
摘要:Carbon dots(CDs) are a type of 1-10 nm nanosized particles with carbon as the main element. They show bright prospects in the field of fluorescence analysis and detection due to its many advantages, such as a wide range of synthetic raw materials, high biological safety, strong fluorescence signal, and stable optical properties. Latent fingerprint detection is a classical and reliable identification technology. Latent fingerprint is the trace of human finger secretions on solid contact surface which is hard to distinguish by naked eye. It needs to be processed by physical chemistry to enhance the imaging effect. The application of fluorescent carbon dots to enhanced imaging of latent fingerprints has given full play to the advantages of carbon dots and a series of advances have been made in recent years. In this paper, the common developing methods of latent fingerprints are introduced, the synthesis and preparation of carbon dots, luminescence mechanism, application in latent fingerprint detection, imaging mechanism and efficiency comparison are summarized. The deficiencies and future development direction of carbon dots in latent fingerprint detection are prospected, which provides an important reference for research work in related fields.
摘要:Carbon dots(CDs) possess excellent luminescent properties and a variety of potential applications. Embedding CDs in zeolites with nanoporous structures generates a new class of composite materials with interesting photoluminescence(e.g. room temperature phosphorescence and delayed fluorescence). In this review, the recent research progresses of such composite materials, including the preparation strategies for embedding CDs in zeolites, the regulation of afterglow luminescence, and the effects of host zeolite matrix to guest CDs are summarized. Finally, a brief conclusion and the development prospect of CDs@zeolite materials are presented.
摘要:Carbon dots have the advantages of wide sources of synthetic raw materials, adjustable luminescence performance, and good biocompatibility. They have huge application potential in the fields of bioimaging, ion detection, luminescent materials and other fields. The preparation methods, the luminescence principle and the application of carbon dots are reviewed. The preparation method of carbon dots is emphasized. The latest progress of carbon dots in the fields of catalysis and biological imaging in recent years is summarized. The synthesis of carbon dots is further optimized, and the luminescence mechanism of carbon dots is deeply explored. The preparation of carbon dots with adjustable luminescence wavelength and adjustable size is of great significance for their applications in light-emitting devices, bioimaging, sensing and other fields.
摘要:Because of their low toxicity, easy preparation, good photostability and color-tunable photoluminescence, carbon dots are expected to be a new kind of ideal solid-state photoluminescent materials. However, due to the aggregation-induced fluorescence quenching(ACQ) effect, the development of carbon dots in the field of solid-state photoluminescence is limited. Preparing solid-state emissive carbon dots featuring anti-ACQ ability is an important topic in the field of carbon dot research. On basis of the latest progress in the study of solid-state emissive carbon dots, this review summarizes the synthesis and photophysical properties of these carbon dots with anti-ACQ ability in terms of core/surface state controlling and supramolecular/polymer crosslink-enhanced emission, and discusses the physical mechanisms for the occurrence of the solid-state emission. Moreover, the application progress of these carbon dots in the field of solid-state photoluminescence is introduced, and the current situation and problems they faced are discussed.
摘要:As a new carbon material, carbon dots have exhibited great potential in biomedical, energetic, and environmental applications due to their excellent optical characters, good biocompatibility and catalytic activities. Carbon dots(CDs) with red/near infrared(NIR) light responsive properties possess deep tissue penetration, minimal autofluorescence disturbance and low tissue damage, which makes them to be drawn great attention in biomedical application. In this review, we firstly introduced the factors affecting the absorption/emission properties of CDs, then focused on the recent advances of red/NIR light responsive CDs for the tumor therapy, mainly including photodynamic therapy(PDT), photothermal therapy(PTT) and PDT/PTT synergistic therapy. Meanwhile, based on the feature of tumor microenvironment, we also reviewed the tumor microenvironment(TME) responsive carbon dots and their applications in tumor therapy. Finally, we discussed the present challenges and future prospects of CDs for cancer treatment.
摘要:Carbon dots(CDs), a kind of carbon nanomaterials, have various superiorities, such as small size, good water solubility, high biocompatibility, non-tixicity, simple preparation, and wide raw material sources, thereby attracting more and more attentions from researchers in medical imaging technology, environmental monitoring, chemical analysis, catalyst preparation, energy development. In recent years, CDs have begun to be applied in the field of agriculture, especially in regulating the plant photosynthesis. On the one hand, CDs, due to their good optical properties, can transfer energy or convert light to chloroplasts to improve the electron transport rate, thus accelerating the transformation of light energy to active chemical energy in photosynthesis. On the other hand, CDs can also promote the synthesis of chlorophyll and the activity of photosynthesis-related enzymes, thereby improving the ability of plants to capture light energy and CO2 assimilation. In view of the application prospect of CDs in agriculture, this paper systematically reviewed the research progress of CDs in regulating plant photosynthesis based on the property of CDs and the physiological process of plants. Subsequently, the current problems restricting the application of CDs were summarized. This paper provides reference for the future development of CDs in agriculture.
摘要:Carbon dots are a new class of carbon materials. Due to their ultrasmall size, abundant surface functional groups, good biocompatibility, non-toxicity and photoluminescence characteristics, they have been widely studied since their discovery and have been gradually applied in various fields. In recent years, the application of carbon dots in the new generation of secondary rechargeable batteries has attracted wide attention. In view of the advantages and challenges of the applications of carbon dots in electrode materials of sodium ion batteries, this review takes carbon dots derived carbon materials, surface modification and morphology control of carbon dots on electrode materials as the context, and systematically summarized the applications of carbon dots in electrode materials of sodium ion batteries. The key role of carbon dots in the construction of electrode materials is discussed, and the challenges and future development directions of carbon dots in the applications of sodium ion batteries are analyzed. This review aims to provide a certain reference and basis for the application of carbon dots in energy storage batteries.
关键词:carbon dots;sodium ion batteries;derived carbon materials;surface modification;morphology control
摘要:Recently, the fluorescence biosensor based on carbon dots(CDs) and aptamer is more and more attractive. Comparing with traditional fluorescence materials like fluorescence dye, semiconductor quantum dots and rare earth phosphors, CDs have attracted considerable attention in the field of fluorescence biosensor due to their excellent photoluminescence, low toxicity and low-cost prepare process. The fluorescence biosensor based on CDs and aptamer has extensive application prospect in the field of environment monitoring, bioimaging and biomedicine. This review will summarize the structural composition, fabrication methods, sensing mechanism and application area of fluorescence biosensor based on CDs and aptamer.
摘要:As a self-luminescence phenomenon without light, heat, sound, electricity and magnetism excitation, chemiluminescence has been widely used in chemical analysis, cold light source, bioimaging and related fields. For most chemiluminescent systems, their chemiluminescence depends not only on the substrates of chemical reactions, but also on the catalysts and chemiluminescent intermediates. Carbon dots are a new type of zero-dimensional luminescent carbon nanomaterials, which have been widely used in various chemiluminescent systems due to their excellent physicochemical properties, rich structure and morphology. On basis of the chemiluminescent systems of luminol and peroxyoxalate, this paper summarizes the research advances in carbon dot-based luminol and peroxyoxalate chemiluminescent systems, also discusses the possible mechanism and related application of carbon dot-based chemiluminescence in luminol and peroxyoxalate systems, which provides ideas for the synthesis of nanomaterials with specific chemiluminescent properties and promotes the further development of chemiluminescent nanomaterials.
摘要:As one of the emerging carbon nanomaterials, carbon dots(CDs) have a wide application in biomedical field because of their unique physical and chemical properties such as low cytotoxicity, strong hydrophilicity, good biocompatibility, excellent photostability, adjustable luminescence and easy modification. In this review, we mainly discuss the applications of CDs in biological imaging, drug/dye/protein/gene delivery and cancer diagnosis and treatment. Furthermore, we discuss the current challenges and future prospects of CDs in biomedical applications.
摘要:Carbon quantum dots(CQDs), as a new type of fluorescent carbon nanomaterials, have the advantages of a wide range of raw materials, simple preparation, easy operation, high sensitivity, excellent luminescence performance and easy visualization. In recent years, they have been used in drug analysis and the detection of small biological molecules has great application potential. This article mainly reviews the analytical applications of CQDs as fluorescent sensors in some antibacterial drugs, anti-inflammatory drugs, anti-tumor drugs, multivitamins and some small drug molecules. And the development of CQDs in drug analysis is also prospected.
摘要:The aggregation of carbon quantum dots leads to serious fluorescence quenching, which greatly reduces the luminescence efficiency and hinders the application of carbon quantum dots as luminescent materials in display and lighting devices. The host-guest doping scheme can effectively solve the above problems, but the water-soluble carbon quantum dots can not match the organic host materials. In view of this, in this paper, the oil solubility of the carbon quantum dots was guaranteed by grafting the aromatic functional groups with liophilic properties on the surface of the carbon quantum dots, so that the carbon quantum dots had certain carrier transport performance. The yellow oil-soluble carbon quantum dots with a light peak of 533 nm and a fluorescence quantum yield of 43% were prepared by this scheme. The carbon quantum dots were dispersed into polymethyl methacrylate(PMMA) and coated on the surface of UV light emitting diode(365 nm) lamp beads. The photoluminescent devices were prepared with a bright yellow light(560 nm) and a maximum luminance of 23 000 cd/m2.Furthermore, the carbon quantum dots were doped into polyethylene carbazole(PVK) as the luminescent layer to fabricate host-guest doped electroluminescent devices. The emission peak of the devices is 552 nm, and the maximum luminance of the devices reaches 35.07 cd/m2. The above studies indicate that the synthesis of oil-soluble carbon quantum dot luminescent materials and doping them into the parent material as the luminescent layer can effectively suppress the fluorescence quenching induced by carbon quantum dot aggregation, which is of great significance for the development of high-performance carbon quantum dot based luminescent devices.
关键词:carbon quantum dots;light-emitting diode;Triphenyl methyl;Host and guest doped luminescent layer;brightness
摘要:Since the signal change of the fluorescence in ion detection has always been affected by factors such as photobleaching, light scattering and instability of the light source, the reliability of the sensing system is significantly reduced. Therefore, a nano-scale composite material(S,N-CQDs@GMP/Tb) guided by rare earth terbium coordination has been designed in this paper. The experiment is to assemble terbium ions(Tb3+) and guanosine monohydrate(GMP) on the basis of sulfur and nitrogen co-doped carbon quantum dots. The material can show the coexistence of four transition signals of rare earth ions 5D4→7FJ (J=6, 5, 4, 3) and the blue light emission of the carbon dots when excited by an excitation wavelength of 305 nm. The introduction of mercury ions suppresses the green light of rare earth and increases the blue light of carbon dots. Fluorescence titration experiments show that the ratio of green/blue light has a linear relationship with the concentration of mercury ions. The detection limit is as low as 7.04 nmol·L-1 and the linear range is 10-110 nmol·L-1(R2= 0.982 9). In order to solve the problem of difficult access to powder materials, the experiment uses filter paper as a substrate to obtain a simple solid-phase detection device, which provides a new way for the specific identification of pollutant ions.
关键词:guanosine monophosphate;terbium ion;ratio fluorescent probe;mercury ion
摘要:Semiconductor quantum dots(QDs) have attracted much attention in the design and mechanism of photocatalysts due to their precise size control, unique photoelectric properties and abundant surface active sites. Unlike traditional semiconductor QDs that are mainly used as light absorption units, the emerging carbon dots show excellent application potential in different aspects of photocatalysis, such as enhancing light absorption, promoting charge separation, and increasing surface reaction sites. However, the small size of QDs photocatalysts also leads to serious charge recombination, easy agglomeration and poor stability, which severely limits their photocatalytic performance. One of the main pathways to solve these problems is to load zero dimensional(0D) QDs on ultra-thin two-dimensional(2D) nanosheets to form 0D/2D nanocomposites, which can make the QDs better dispersed and more stable. The accelerated charge transfer promoted by 2D nanosheets can inhibit the recombination of photogenerated charges carriers, which can subsequently improve the activity and stability of QDs-based photocatalysts. In this review, the construction and application of semiconductor QDs and carbon dots based 0D/2D heterojunction photocatalysts are systematically introduced, with special attention to the discussion of the mechanism and challenges of different types of 0D/2D heterojunction photocatalysts. Finally, future development is analyzed and prospected for the 0D/2D heterojunction photocatalysts.
摘要:Nitrophenols are regarded as serious pollutants, especially 2-nitrophenol(2-NP) and 4-nitrophenol(4-NP), deriving from processing and manufacturing as well as being used as raw materials for pharmaceutical industry. They have been proved as a crucial threat to environmental waters due to their good solubility, strong stability, high toxicity, and carcinogenicity. Blue fluorescent carbon dots(MSA-CDs) have been prepared by hydrothermal method using mercaptosuccinic acid as carbon resource. The CDs emitted blue fluorescence emission at 437 nm excited at 340 nm, with quantum yield(QY) of 32%. In this work, the CDs exhibited specific responses to 4-NP and 2-NP. CDs can be used as a fluorescent probe, and showed clear fluorescence quenching in presence of 4-NP and 2-NP with the detection limits of 4-NP and 2-NP at 18.3 nmol/L and 24.0 nmol/L, respectively. The CDs can be used to recognize 4-NP and 2-NP in actual water with high recovery, which indicates that the CDs exhibit more extensive application advantages and possibilities.
摘要:It is of significance to explore the simple synthetic method and near-infrared ratio fluorescence probe. In this paper, carbon quantum dots(CDs) with near-infrared double-emission fluorescence properties were synthesized by solvothermal reaction in 200 ℃ high pressure reactor for 10 h using Ficus alba leaves as carbon source, ethanol and acetone as extraction agent. Transmission electron microscopy(TEM) showed that the average size of CDs is about 4.70 nm and the lattice constant is 0.32 nm. X-ray diffraction(XRD) results showed there is a wide diffraction peak at near 2θ=22°. It showed the CDs was amorphous carbon sp2 hybridized. Fourier transform infrared spectroscopy (FT-IR) indicated the CDs had amino, carbonyl, alcohol hydroxyl, and methyl. Fluorescence spectra showed that the maximum excitation wavelength was 410 nm, and the maximum emission wavelength was 466 nm and 676 nm. Using quinine sulfate as a reference, the fluorescence quantum yield was 26.31%.The stability of acid-base, optical, salt resistance and metal ion resistance and the effect of cell imaging were also discussed. The above results show the CDs has the advantages of cheap raw materials, easy to produce, stable to acid and alkali, good photobleaching resistance and so on. It has good prospects for optical imaging applications.
摘要:Carbon dots(CDs) were successfully prepared by the one-pot pyrolysis method using the barley seedling as carbon source. The boron, nitrogen and mixed doping system of CDs were studied. The solution of CDs exhibits broad absorption in the UV region. Two emission bands can be observed in the near UV and blue regions. It is worth to note that CDs powder doped with B and co-doped with B and N can be effectively excited by the blue light and emit bright green light. The LED devices were fabricated by combining such two kinds of CDs powder, which exhibit excellent luminescent properties. Using commercial K2SiF6∶Mn4+ as red components, white LEDs with high luminous efficiency and color rendering index can be obtained.