荧光碳点在脊椎类模式动物斑马鱼中的活体成像与毒理学研究

将荧光碳点引入透明斑马鱼胚胎中,研究了荧光碳点在斑马鱼中的活体成像和对斑马鱼的毒副作用。通过对水中添加荧光碳纳米颗粒,从形态上观察其对于斑马鱼个体发育的生物学效应,实时观察其在斑马鱼体内富集代谢的情况,为荧光碳点及其复合物在生物活体成像方面的研究应用奠定基础。结果表明,荧光碳点对斑马鱼生长发育无明显的毒副作用,不会导致胚胎发育异常(通过观察尾巴弯曲情况、色素深浅、血管发育速度、鱼鳔发育速度来确定对胚胎发育的影响),并且对斑马鱼无明显致死现象。荧光碳点进入斑马鱼体内的时间非常迅速,并且可以在48 h之内经代谢排出体外。     

Green Synthetic Approach for Synthesis of Fluorescent Carbon Dots for Lisinopril Drug Delivery System and their Confirmations in the Cells

In this work, highly luminescent carbon dots (CDs) were synthesized by the hydrothermal method at 170 °C for 12 h using pasteurized milk as a carbon source. The prepared CDs exhibited bright blue fluorescence under UV light illumination at 365 nm. The CDs show fluorescence life time of ~4.89 ns at excitation wavelength of 370 nm. The effect of different solvents on the fluorescence property of CDs was also investigated. The lisinopril (Lis)-loaded CDs were fabricated by self-assembly of lisinopril on the surfaces of CDs, which were characterized by UV-visible and FT-IR spectroscopic techniques. The controlled release of lisinopril from the Lis-CDs was realized at pH values of 5.2, 6.2 and 7.4, respectively. The results of the cytotoxicity and confocal laser scanning microscopic images indicate that the Lis-CDs were successfully uptaken by HeLa cells without apparent cytotoxicity. The synthesized CDs show great potential as drug vehicles with good biocompatibility, sustained release of lisinopril from CDs, indicating that the CDs can act as a promising drug delivery system for therapeutic delivery and/or bioimaging applications.     

A solvent-governed surface state strategy for rational synthesis of N and S co-doped carbon dots with multicolour fluorescence

ABSTRACT

Multicolour emissive carbon dots (CDs) are widely investigated by virtue of their merits on fluorescent properties. Method on heteroatom doping assisted with various solvents has been proved efficient in achieving multiple-colour-emissive CDs, especially long-wavelength emission. Herein, a synthesis of multicolour-emissive CDs by controlled surface function is reported. By tuning the thermal-pyrolysis temperature and molar ratio of reactants, optimal emission of the resulted CDs gradually shifts from blue to yellow light with the assistance of different solvents. According to the emissive relationship dependent on excitation, fluorescence lifetimes, and FT-IR of these CDs, the different surface states participated with S and N elements on the surface of carbogenic core govern fluorescent colours of the CDs. In terms of the applications, blue CDs (B-CDs) exhibits high sensitivity for ion detections of Ag⁺ and Fe³⁺, which is further illustrated to have different quenching mechanisms each other because that these ions have the affinity interaction with different surface groups of the CDs. Moreover, blue and yellow CDs solutions are mixed with PVP water solution to fabricate white-light CDs/PVP film, which exhibits stable fluorescence with a CIE coordinate of (0.32, 0.33) and endows these CDs as potentially fluorescent nanomaterial in the solid state lighting field.     

Preparation and Biomedical Applications of Multicolor Carbon Dots: Recent Advances and Future Challenges

Multicolor carbon dots (CDs) as an emerging subclass of carbonaceous nanomaterials have inspired intensive attention due to the fascinating fluorogenic properties of quantum dots, exhibiting great potential applications in the biomedical field. In some cases, reported CDs with blue or green fluorescence are not desirable for further biological applications owing to the conflicting background autofluorescence, low penetration, and relatively large damage to biological tissue. However, multicolor CDs that can work in the longer wavelength region are being developed to address this issue by overcoming the autofluorescence from the cellular components (usually in the blue and green range). In this review, the development of multicolor CDs is described comprehensively, including for red-emissive or NIR-emissive CDs. Additionally, the preparation methods of multicolor CDs are summarized. Moreover, the factors affecting the luminescence of multicolor CDs are discussed in detail, and the biomedical applications are emphasized from multiple perspectives.     

Sonochemical synthesis of carbon dots,mechanism, effect of parameters,and catalytic,energy, biomedical and tissue engineering applications

Carbon-based nanomaterials are gaining more and more interest because of their wide range of applications. Carbon dots (CDs) have shown exclusive interest due to unique and novel physicochemical, optical, electrical, and biological properties. Since their discovery, CDs became a promising material for wide range of research applications from energy to biomedical and tissue engineering applications. At same time several new methods have been developed for the synthesis of CDs. Compared to many of these methods, the sonochemical preparation is a green method with advantages such as facile, mild experimental conditions, green energy sources, and feasibility to formulate CDs and doped CDs with controlled physicochemical properties and lower toxicity. In the last five years, the sonochemically synthesized CDs were extensively studied in a wide range of applications. In this review, we discussed the sonochemical assisted synthesis of CDs, doped CDs and their nanocomposites. In addition to the synthetic route, we will discuss the effect of various experimental parameters on the physicochemical properties of CDs; and their applications in different research areas such as bioimaging, drug delivery, catalysis, antibacterial, polymerization, neural tissue engineering, dye absorption, ointments, electronic devices, lithium ion batteries, and supercapacitors. This review concludes with further research directions to be explored for the applications of sonochemical synthesized CDs.     

Carbon Dots and Stability of Their Optical Properties

Carbon dots (CDs) are a new class of materials which have been extensively studied due to their unique optical properties, low toxicity, and abundance of raw materials to synthesize them. In this minireview, it is highlighted that the stability of the optical properties of CDs is an important aspect that has received very little attention. While CDs are usually considered to be photostable, several recent reports show they are prone to photobleaching. Studies of blinking, photobleaching, and photoswitching of CDs are reviewed here. It is noted that there is a lack of systematic studies about the photostability of CDs, and efforts are needed to further study this aspect. Furthermore, it is observed that the stability of CDs is somewhat related to their photoluminescence quantum yield, excitation dependence of PL emission, precursor, and synthesis method used to produce CDs.     

Fullerene‐Structural Carbon‐Based Dots from C60 Molecules and their Optical Properties

Fullerene‐structural carbon‐based dots (f‐CDs) are synthesized for the first time by chemically oxidizing fullerene molecules (C₆₀) using concentrated HNO₃. The lateral sizes of the f‐CDs distribute in the range of 7–20 nm, and the heights mainly range from 0.4 to 1.3 nm with an average value of 0.7 nm. The presence of massive pentagonal carbon units makes the f‐CDs different from most of graphitic‐CDs in structure and morphology. The f‐CDs exhibit unique luminescent properties such as photoluminescence (PL) and electrochemiluminescence. Based on the investigation of the UV–vis absorption and luminescent properties, a novel and reasonable model is proposed for the PL mechanism of f‐CDs. Furthermore, the obtained f‐CDs show low cytotoxicity and have potential application in cell imaging.     

Synthesis of Novel Fluorescent Cyclohexenone Derivatives and their Partitioning Study in Ionic Micellar Media

An approach is demonstrated toward the synthesis of four novel cyclohexenone derivatives (CDs) via a convenient route of Michael addition of ethyl acetoacetate. The molecular structures of CDs were confirmed by means of FT-IR, ¹H NMR, EIMS, UV and also by X-ray single crystal structure analysis. CDs are strongly fluorescent compounds and their fluorescent spectra exhibits intense violet fluorescence. To model the binding to biological membranes the behavior of CDs in micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) and an anionic surfactant, sodium dodecylsulfate (SDS) has also been examined. The characteristics of partition and binding interactions of CDs with CTAB and SDS were investigated by UV-Visible and fluorescence spectroscopic techniques. Higher values of all mentioned interactions in case of CTAB, compared to SDS, indicate that there are greater interactions between the CDs and CTAB than with SDS.     

溶剂热法合成橙-绿双波段荧光碳点

荧光碳点具有激发波长依赖的独特性质,有望基于此制备检测溶液pH值的荧光探针。以柠檬酸和尿素为原料、N,N-二甲基甲酰胺为溶剂,采用一步溶剂热法在200℃下保温12 h制备了一种新型的具有橙-绿双波段荧光发射性能的水溶性碳点。采用透射电子显微镜、X射线衍射、拉曼光谱、傅里叶变换红外光谱和X射线光电子能谱等方法对荧光碳点的组成和形貌进行了表征,还通过荧光发射光谱和紫外-可见吸收光谱对其光学性能进行了研究。结果表明,制备的碳点粒径为2.7~4.3 nm,表面带有大量含氧官能团,具有良好的水分散性。在440 nm和540 nm波长光激发下分别呈现绿色(500 nm)和橙色(590 nm)双波段荧光发射。合成的荧光碳点发光性能对pH值具有敏感性:在强碱性溶液中,590 nm的荧光强度比水溶液中提高了6.71倍,同时吸收峰的蓝移使得自然光下其溶液颜色发生了明显改变,具有强碱性指示剂的作用;在pH值为2~6的酸性溶液中,500 nm与590 nm发光峰强度比与pH值之间呈现良好的线性关系,展现了作为pH值比率荧光探针的应用潜力。     

Introduction to the Performance and Mechanism of Various Photocatalytic Materials Compounded with Carbon Dots

With their unique optical and electronic properties, carbon dots (CDs) are showing great momentum in many fields such as biosensing, imaging, drug delivery, and photocatalysis. Due to their efficient light harvesting, extraordinary upconversion photoluminescence, and excellent photoinduced electron transfer capabilities, the combination of CDs with photocatalytic materials will promote light absorption resulting in increased generation of electron-hole pairs and faster photogenerated electron transfer, effectively suppressing the rate of electron-hole pair complexation and thus improving photocatalytic activity. In this paper, the mechanism of CDs photocatalysis and various photocatalytic materials such as TiO₂, Bi-based, CdS, and g-C₃N₄ complexed with CDs are reviewed. It is hoped that research into CDs in the field of photocatalysis will be advanced and that CDs will be used more widely in environmental and energy applications.     

Facile Synthesis of Mg2+‐Doped Carbon Dots as Novel Biomaterial Inducing Cell Osteoblastic Differentiation

Carbon dots (CDs), as an emerging fluorescent nanomaterial with low toxicity, has been widely applied in various bio‐related fields. However, investigations on their capabilities in guiding osteogenic differentiation are rarely seen, which has great significance in osteoporosis therapy and bone regeneration. Herein, for the first time, a new kind of Mg²⁺‐doped CDs is facilely synthesized through a one‐step hydrothermal method from metal gluconate salts. The CDs can serve as nanocarrier of Mg²⁺ ions entering into cells, and the bioessential metal ions subsequently stimulate osteoblastic differentiation by improving alkaline phosphatase (ALP) activity and upregulation related mRNA expression. Noteworthy, the raw material has almost negligible performance on osteoblastic differentiation compared to Mg‐CDs, which is due to the ultrasmall sizes of CDs and the efficient uptake by cells. Moreover, benefitting from the fluorescence properties, Mg‐CDs can also be applied as cell labeling agents. This work proposes a new strategy to synthesize multifunctional metal ion‐doped CDs, which might had great potential in serving as promising nanodrugs for bone loss therapy.     

Coal Pitch Derived Yellow-Emissive Carbon Dots and Their Application in Luminescent Solar Concentrators

Using coal pitch as the carbon source to synthesize carbon dots (CDs), one of the most promising photoluminescence (PL) materials, can play an important role in the global demand for carbon neutralization. However, the reported CDs derived from coal pitch are mainly limited blue emission. Here, a new route to synthesize yellow-emissive CDs from coal pitch is developed by extracting the lightweight aromatic compounds from coal pitch and solvothermally treating the extracts in dichloromethane in the presence of a small amount of nitric acid and sulfuric acid. Notably, the obtained CDs exhibit excitation independent yellow emission, large Stokes shift and good photostability. The application of the CDs for luminescent solar concentrators (LSCs) is evaluated. It is found that the CDs can be well dispersed in polymethyl methacrylate (PMMA) matrix and fabricated transparent LSCs. The synthesized LSC (4 × 4 × 0.2 cm³) with the optimal CDs concentration exhibits an optical conversion efficiency (η_opt) of 3.31% and power conversion efficiency (η_PCE) of 1.95% under simulated sun light illumination (100 mW cm⁻²). This research offers a new strategy to synthesize new kind of CDs with desired performance by exploiting the native chemistries of coal pitch.     

Versatile Fluorescent Carbon Dots from Citric Acid and Cysteine with Antimicrobial,Anti-biofilm,Antioxidant, and AChE Enzyme Inhibition Capabilities

Nanostructured fluorescent particles derived from natural molecules were prepared by a green synthesis technique employing a microwave method. The precursors citric acid (CA) and cysteine (Cys) were used in the preparation of S- and N-doped Cys carbon dots (Cys CDs). Synthesis was completed in 3 min. The graphitic structure revealed by XRD analysis of Cys CDs dots had good water dispersity, with diameters in the range of 2–20 nm determined by TEM analysis. The isoelectric point of the S, N-doped CDs was pH value for 5.2. The prepared Cys CDs displayed excellent fluorescence intensity with a high quantum yield of 75.6?±?2.1%. Strong antimicrobial capability of Cys CDs was observed with 12.5 mg/mL minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria with the highest antimicrobial activity obtained against Staphylococcus aureus. Furthermore, Cys CDs provided total biofilm eradication and inhibition abilities against Pseudomonas aeruginosa at 25 mg/mL concentration. Cys CDs are promising antioxidant materials with 1.3?±?0.1 μmol Trolox equivalent/g antioxidant capacity. Finally, Cys CDs were also shown to inhibit the acetylcholinesterase (AChE) enzyme, which is used in the treatment of Alzheimer’s disease, even at the low concentration of 100 μg/mL.

     

以醇溶剂为碳源制备碳点的荧光性能

以乙二醇和丙三醇为碳源,用一元醇（异丙醇和乙醇）为对比,通过溶剂热法制备得到碳点。通过傅里叶红外光谱、紫外-可见吸收光谱和激发光谱对所制得的碳点进行表征和分析,探讨了不同碳源对碳点的表面官能团、荧光性能等的影响,从而分析其荧光的发光机理。结果表明：乙二醇与丙三醇制备的碳点含有C=C键和C=O键,均在365 nm光激发后在450 nm处有荧光峰;而一元醇是由C-OH基团中的孤对电子产生荧光,碳源分子中羟基含量对碳点的荧光性能有很大影响,羟基含量越高,越容易形成双键结构。     

One step synthesis of ultra-high quantum yield fluorescent carbon dots for “on-off-on” detection of Hg2+ and biothiols

In this paper, the carbon dots (CDs) with strong blue fluorescence were synthesized through hydrothermal method, which using folic acid, ammonium citrate and ethylenediamine as precursors. The prepared CDs with a high absolute quantum yield of 81.94% and showed excellent stability in high concentration salt solution and different pH conditions. With the addition of Hg²⁺, the signal of CDs was selectively quenched. At the same time, the CDs-Hg²⁺ system could be recovered after the introduction of biothiols. Moreover, the fluorescence of CDs showed a good linear relationship with Hg²⁺ (1–15 µM), and the detection limit as low as 0.08 µM. In addition, the prepared CDs with low toxicity could be used to detect Hg²⁺ in living cells and actual water samples.

     

Nitrogen-doped carbon dots embedded in a SiO<Subscript>2</Subscript> monolith for solid-state fluorescent detection of Cu<Superscript>2+</Superscript> ions

We describe the simple fabrication of SiO₂ sol-gel monoliths embedding highly luminescent carbon nanodots (CDs) sensitive to metal ions. The pristine CDs we synthesize display an intense dual emission consisting in two fluorescence bands in the green and violet region, and we demonstrate that this photoluminescence is substantially unchanged when the dots are incorporated in the SiO₂ matrix. The emission of these CDs is quenched by interactions with Cu²⁺ ions, which can be used to detect these ions with a detection limit of 1 μM. The chromophores remain accessible to diffusing Cu²⁺ ions even after embedding CDs in the sol-gel monolith, where their detection capabilities are preserved. Such a result provides the proof-of-principle of a new sensing scheme, where CDs are exploited as active sensing centers of metal transition ions within a solid-state device. The different interaction mechanisms of CDs with copper, in liquid and solid phase, are analyzed in detail and discussed in terms of different accessibility of their chromophores when the dots are incorporated in the SiO₂ matrix.     

The Preparation of Cu(II)- and Ag(I)-responsive Carbon Nanodots from the Right Amino-acid Carbon Source

Journal of Fluorescence - Carbon nanodots (CDs) have exhibited excellent sensing capability for various metal ions. However, it is difficult to determine the selectivity of CDs to metal ions. In...     

Synthesis,spectroscopic characterization,and computed optical analysis of green fluorescent cyclohexenone derivatives

Cyclohexenone containing chalcones core is one important class of materials, which exhibit high nonlinear optical (NLO) responses and good crystallizability. The present study reports the successful development of six new fluorescent cyclohexenone derivatives (CDs) via conventional Robinson annulation method. The molecular structures of these newly synthesized CDs were confirmed by using various analytical techniques such as ¹H NMR, ¹³C NMR, FTIR, EIMS, UV–Vis spectroscopy and single crystal X‐ray diffraction. The crystallographic data revealed that the spatial structure of the representative CD (4BE) belongs to monoclinic, P2₁/c space group. The results from luminescence studies show that the CDs molecules apparently emit intense green light at room temperature in aqueous media. The relative polarity and molecular chemical stability of the CDs molecules were predicted by measuring the molecular electrostatic potential and frontier molecular orbital energy. In addition, the UV–Vis spectra, transition character and electronic structures of these CDs were computed by using quantum chemical methodology. It was interesting to note that the values of computed and experimental electronic transitions (λ_max) were in good agreement and these CDs display high hyperpolarizability (β) values. The present work will be helpful for systematical understanding of the structures and the optical properties of CDs for studying the structure–activity relationship that will suggest their potential application in photonic devices. Copyright © 2015 John Wiley & Sons, Ltd.     

Dynamic and thermodynamic properties of porous vortex matter in Bi(2)Sr(2)CaCu(2)O(8) in an oblique magnetic field

Vortex matter in Bi(2)Sr(2)CaCu(2)O(8) with a low concentration of tilted columnar defects (CDs) was studied using magneto-optical measurements and molecular dynamics simulations. It is found that while the dynamic properties are significantly affected by tilting the magnetic field away from the CDs, the thermodynamic transitions are angle independent. The simulations indicate that vortex pancakes remain localized on the CDs even at large tilting angles. This preserves the vortex thermodynamics, while vortex pinning is considerably weakened due to kink sliding.     

Facile fabrication of SERS-active substrates based on discarded silver compact disks

Surface-enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it still remains a grand challenge for creating a general substrate by a simple and low-cost way. Herein, we report our attempt to address this issue by fabricating SERS-active substrates based on discarded silver (Ag) compact disks (CDs). The revealed Ag layer on the CDs after removing its protective film can be used as SERS substrate directly and exhibited a good SERS activity. The Ag CDs was further roughened by electrochemical oxidation-reduction cycle in 0.1 M KCl and improved its SERS activity greatly. The effects of roughened parameters on the SERS activity were investigated in detail. Moreover, a sandwich structure consisting of Ag nanoparticles, p-aminobenzenethiol and roughened Ag CDs was fabricated as an example to further enhance the SERS activity for detection in ultra-high sensitivity. These SERS-active substrates based on Ag CDs are all low-cost and allowing a “one way use”. The fabrication is also very simple and exhibits great potential for extensive application.