Microwave-Assisted Green Synthesis of Carbon Quantum Dots Derived from Calotropis Gigantea as a Fluorescent Probe for Bioimaging

Journal of Fluorescence - An eco-friendly, cost-effective, and convenient approach for synthesizing biocompatible fluorescent carbon quantum dots (CQDs) from the leaf extract of the medicinal plant...     

pH响应型碳点的荧光机制和生物医学应用

碳点(CDs)作为一种新型的零维碳基纳米材料,由于其优异的荧光性质、良好的生物兼容性、低细胞毒性以及丰富的表面官能团等性质,在荧光传感和生物医学领域具有巨大的应用潜力。特别是针对肿瘤弱酸性的微环境特点,设计pH响应型碳点来实现对肿瘤的特异性治疗将尤为重要。本文对近年来基于pH响应型碳点的研究工作进行了系统的调研,综述了pH响应型碳点的荧光机制及其在pH传感、生物成像及癌症治疗等生物医学领域的应用,并对pH响应型碳点目前面临的主要挑战以及未来发展的方向进行了展望。     

Green and Cost Effective Synthesis of Fluorescent Carbon Quantum Dots for Dopamine Detection

Carbon quantum dots (CQDs) due to its high fluorescent output is evolving as novel sensing material and is considered as future building blocks for nano sensing devices. Hence, in this investigation we report microwave assisted preparation and multi sensing application of CQDs. The microwave derived CQDs are characterized by Dynamic Light Scattering (DLS) experiment and Fourier Infrared spectra (FTIR) to investigate the size distribution and chemical purity respectively. Fluorescent emission spectra recorded at varying pH shows varying fluorescence emission intensities. Further, emission spectra recorded at different temperatures shows that fluorescence emission of CQDs greatly depends on temperature. Therefore, we demonstrate the pH and temperature sensing characteristics of CQDs by fluorescence quenching behaviour. In addition, the interaction and sensing behaviour of CQDs for dopamine is also presented in this work with a detection limit of 0.2 mM. The steady state and time-resolved methods have been employed in fluorescence quenching methods for sensing dopamine through CQDs at room temperature. The bimolecular quenching rate constants for different concentration have been measured. The interaction between CQDs and dopamine indicates fluorescence quenching method is an elegant process for detecting dopamine through CQDs.     

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.     

Carbon Quantum Dots As Antibacterial Photosensitizers and Their Polymer Nanocomposite Applications

Carbon quantum dots and their incorporation in various polymer matrices are reviewed. In general, the importance of such polymer nanocomposites in biomedical applications is highlighted. In particular, the physical and antimicrobial properties of carbon quantum dots and their ability to produce reactive oxygen species under certain conditions using the principle of photodynamic therapy are explored. The characterization, preparation, mechanism of action, and use of carbon quantum dots are discussed. The known combinations of polymers and carbon quantum dots and their use in various industries are also described.     

Facile Synthesis of Carbon Dots from Biomass Material and Multi-Purpose Applications

Selective and sensitive water content measurement in organic solvents is extremely significant for both industrial use and laboratory preparation. Carbon nanodots are promising carbon nanomaterials with unique and novel properties and thus have drawn growing attention. However, the hydrothermal approach for the preparation of carbon dots always uses water as solvent, and consequently, the development of carbon dots from biomass materials for fluorescence detection of water content remains unexplored. Here, carbon dots were prepared from gallic acid via a cheap and facile one-step method. The as-prepared carbon dots present excellent sensitivity and selectivity toward water content and exhibits good linear relationships with water content in range of 0–10%. The carbon dots demonstrated a strong antioxidation capacity and colour-reaction of Fe³⁺ like gallic acid. The carbon dots also showed solid-state lighting.

     

Doping and Surface Modification of Carbon Quantum Dots for Enhanced Functionalities and Related Applications

Carbon quantum dots (CQDs) are a unique class of 0D nanomaterials, featured by a graphitic core and shell layers saturated with hydrogen atoms and functional groups. CQDs are prepared through top-down and bottom-up strategies from natural and synthetic precursors. CQDs can be modified through chemical (e.g., surface functionalization/passivation, doping, etc.) and physical (e.g., core–shell architecture, composite material blending, etc.) strategies to control their properties. This review highlights the effect of such modifications on the photophysical properties of CQDs, such as photoluminescence (PL), absorbance, and relaxivity. The dependence of PL upon the size, orientation at the edges, surface and edge functionalization, doping, excitation wavelength, concentration, pH, aggregate formation, etc., are summarized along with the supporting theoretical evidence available in the literature. Also, this review outlines the recent advancements, and future prospective of optical (e.g., sensing, bioimaging, and fluorescent ink) and catalytic applications (e.g., photocatalysis and electrocatalysis) of CQDs enhanced through physical and chemical modifications of their structure and composition.     

Highly Sensitive and Selective Detection of Amoxicillin Using Carbon Quantum Dots Derived from Beet

In the present work, we synthesized the carbon quantum dots (CQDs) by one step hydrothermal method using the dried beet powder as the carbon source without additional chemical reagents and functionalization. The as-prepared CQDs are quasi-spherical carbon nanoparticles with diameters of 4–8 nm as well as surface functional groups such as carboxyl and hydroxyl groups, and exhibit good water-solubility, biocompatibility, and strong fluorescence. It is confirmed that amoxicillin (AMO) could enhance the fluorescent intensity of CQDs, the I/I₀ showed a linear correlation between the intensity of fluorescence and the concentration of AMO in a broad range. These superior properties render a potential application of the CQDs in biomedical.     

生物质碳量子点的绿色制备及对Cu2+的检测

向日葵作为我国主要的油料作物之一,其秸秆是天然的纤维素材料,具有绿色无毒,成本低廉的优势,是制备生物质碳量子点的理想材料之一。近年来,由于含铜农药和化学肥料的不规范使用,大量含铜污染物被排放导致农田土壤和水环境中的铜含量远高于环境背景值。因此,迫切需要开发出一种选择性好、灵敏性强且对环境友好的Cu²⁺检测方法。碳量子点(CDs)是一种粒径小于10 nm的准球形荧光碳纳米材料,因其表面含有丰富的极性官能团,具有良好的水溶性而被广泛研究。与传统的半导体量子点(CdSe, CdTe)相比,CDs具有合成原料广泛、生物相容性好等优点。主要应用于生物成像、光催化、光电转化以及传感检测等领域。然而目前用于碳化合成CDs的前驱体大多为昂贵的化学品,且合成过程复杂污染环境,限制了CDs的大规模生产与应用。开发出一种生态友好,简单、廉价的CDs合成方法是很有意义的。本研究以废弃的向日葵秸秆为碳源,采用简便的水热法合成生物质碳量子点(S-CDs)作为荧光探针,用于检测识别Cu²⁺。通过对S-CDs的一系列光学性质分析与表征,鉴定出其表面官能团主要包括O—H, N...     

A Review on Characterization Techniques for Carbon Quantum Dots and Their Applications in Agrochemical Residue Detection

Journal of Fluorescence - Carbon quantum dots (CQDs) have emerged as one of the most promising nanomaterials in the carbon nanostructures family in recent years due to their low toxicity, simple...     

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.     

Preparation and Characterization of the Fluorescent Carbon Dots Derived from the Lithium‐Intercalated Graphite used for Cell Imaging

Zero‐dimensional fluorescent carbon dots (CDs) that are used as a cell‐imaging reagent are prepared by using a simple and effective route employing lithium‐intercalated graphite from lithium‐ion batteries as a carbon source. Under ultrasonic exfoliation, the interlayer space increases, while the layer distortion and remaining lithium of the lithium‐intercalated graphite are utilized to disrupt the graphitic structure and produce the CD suspension. Subsequently, after concentration and purification, the obtained colloidal CD suspension has a fluorescent yield of up to 1.2% and is therefore comparable to the CDs prepared in previous reports. These CD products are water‐soluble, nanosized (approximately 3.5 nm), and biocompatible and can easily enter into HeLa cells to act as a cell‐imaging reagent without any further functionalization. In addition, these CDs do not impose toxicity against HeLa cells and have high photostability with low photobleaching and demonstrate potential applications for bio‐labeling as well as solution state optoelectronics.     

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.     

Fluorescent Carbon Quantum Dots Functionalized by Poly L-Lysine: Efficient Material for Antibacterial,Bioimaging and Antiangiogenesis Applications

Journal of Fluorescence - This study illustrates the synthesis of functionalized carbon quantum dots (CQDs) by the one-pot pyrolysis method. The functionalization agent used in CQD synthesis was...     

Amphiphilic Carbon Dots with Excitation-Independent Double-Emissions

Developing total carbon-based multicolor emissive carbon dots (Cdots), especially amphiphilic Cdots (A-Cdots) with several luminescent bands and limited emissive sites, is still a challenge. Herein, A-Cdots with bright excitation-independent blue/yellow photoluminescence (PL) bands from two types of fluorophores are synthesized by the solvothermal treatment of citric acid and dodecylamine in cyclohexane (c-hexane) solution. Due to the hydrogen-bonding interaction of carboxylic groups linked with A-Cdots and the hydrophobic effects of long-chain alkyl groups, assemblies of A-Cdots with reversed micelle-like structure formed in c-hexane solution lead to remarkable yellow-PL (y-PL) with quantum yield of 33.1%. Time-resolved fluorescence and the distinct solvation effects of A-Cdots conclude that the blue-PL and y-PL are from the radiative recombination of emissive sites of amide and carboxylic groups. For the solvent-dependent optical properties and the amplification effect of dual-color PL, the A-Cdots exhibit good potential in the very sensitive detection of trace impurities in alkane solution, such as ethanol in c-hexane with content as low as 0.033% (v/v). With A-Cdots as phosphors, white-light-emitting diodes (WLEDs) are successfully constructed with luminous efficiency of 52.72 lm W⁻¹. This work provides a new thinking for the design of multicolor luminous Cdots materials and their potential applications.     

硒化镉发光量子点的制备及其在有机发光器件中的应用

硒化镉量子点具有随粒径尺寸改变,而产生发光波长调变的特性,目前已被广泛研究。本研究是由化学溶胶法合成不同粒径尺寸的核壳型CdSe／ZnS硒化镉量子点,其表面包覆十六烷基胺,避免分子团聚现象。在由硒化镉成核温度的控制,成功地制备一系列具有各种尺寸粒径的核壳型硒化镉量子点(2—6nm)。本研究也合成了含有纳米金粒子于核壳型硒化镉量子点,实验结果发现：硒化镉发光效率明显的提高。在有机发光器件的应用方面,将发光波长为505nm核壳型CdSe／ZnS量子点掺入溶有发光波长为570nm铱化合物的氯仿溶液时,其溶液的光致发光光谱表明,原量子点的发光特性消失,只有铱化合物的发光依然存在,且其发光强度呈现明显增强趋势,我们推测此现象源自于量子点到铱化合物能量转移的机制。我们也以含有核壳型硒化镉量子点的铱化合物与PVK混合材料为发光层,成功的制作发光二极管器件,器件的发光效率因核壳型硒化镉的掺杂,明显提高2倍多。     

两亲性壳聚糖基聚合物碳点的合成及其在载药方面的应用

通过水热法合成了系列具有高荧光量子产率（42.9%）辛基化壳聚糖基两亲性聚合物碳点荧光材料。利用红外光谱、紫外吸收光谱、光电子能谱、透射电镜、X射线衍射及荧光光谱对聚合物碳点进行了表征。以阿霉素为模型药物,研究了聚合物碳点对阿霉素的载药性能。当辛基取代度为76.42%时,其最大载药量和包封率分别为49.6%与47.4%。在磷酸盐缓冲液中,载药纳米胶束呈前期快速释放,后期缓慢释放的双相特征。将载药纳米胶束与鼻咽癌细胞作用,发现其存活率随着载药纳米胶束加入量的增加而降低,说明该纳米胶束对鼻咽癌细胞有一定的抑制作用。总之,该聚合物碳点材料在药物载体与荧光示踪方面有潜在的应用价值。     

量子点的荧光特性在生物探针方面的应用

量子点具有传统有机荧光染料无可比拟的光学魅力,在生物医学及材料领域已引起广泛的兴趣,许多科学工作者在量子点用于生物学领域方面已经取得一定进展。目前,量子点最有前途的应用领域是在生物体系中作为荧光标记物。通过观察量子点标记分子与靶分子相互作用的部位,及其在活细胞内的运行轨迹,可能为信号传递的分子机制提供线索,从而为阐明细胞生长发育的调控及癌变规律提供直观依据。文章介绍了量子点研究生物大分子之间的相互作用、生物大分子荧光标记、细胞及生物组织的荧光标记与成像以及活体成像等方面的应用。并概述了纳米量子点作为生物荧光探针的应用前景以及亟待解决的问题。     

碳点用于荧光成像介导的原位膀胱癌靶向光动力/光热治疗

膀胱癌是泌尿系统中最常见的肿瘤之一.目前,化疗与手术切除等治疗手段不能有效治愈该肿瘤,并且上述两种治疗方式会产生副作用,降低患者的生活质量.光疗则为膀胱癌提供了一种新的治疗手段.在本工作中,以靶向膀胱癌细胞的小肽PLZ4修饰多功能碳点,得到了兼具靶向膀胱癌细胞及光动力/光热治疗功能的PLZ-4碳点(PCDs).细胞实验...