碳量子点的合成与应用

近年来,由于碳纳米材料具有高的催化活性以及好的稳定性等优点,其在科学、工程以及商业领域都得到了广泛的应用。其中新型"零维"碳纳米材料--碳量子点(carbon dots, CDs)具有荧光信号稳定、无光闪烁、激发波长和发射波长可调控等独特的光学性质,以及生物毒性小和生物相容性好等优势,逐渐成为碳纳米材料的研究热点,广泛应用于生物成像、生物细胞标记、传感器、光催化、太阳能电池以及发光元件等领域。本文主要综述了CDs的不同合成方法(包括自上而下法和自下而上法)及其应用。     

碳点在样品前处理及色谱分离中的应用

碳点（CDs）具有生物相容性好、毒性低、稳定性好等优点,目前已广泛应用于生物成像、传感、光催化等领域。近年来,以CDs为吸附剂和分离材料的样品前处理和色谱分离研究也引起了研究者的极大兴趣。该文对CDs在样品前处理和色谱分离中的应用进行了综述,并对其发展前景进行了展望。     

碳点的研究进展

碳点具有优良的光学特性、良好的生物相容性和低毒等优点,被广泛用于生物检测、药物传输和生物成像等领域,是极具发展潜力的碳基质材料.近年来,碳点的新型制备方法、性质探索及应用研究引起广泛关注.本文根据碳源和制备方法的不同,将碳点分为石墨烯纳米点和碳纳米点两类,综述了碳点的制备方法,剖析了碳点的发光机理,总结了碳点在生物传感、药物传输和生物成像中的应用;最后分析了碳点存在的问题及应对策略.     

关于碳点性能提升的研究进展

与传统半导体量子点相比,碳点(CDs)由于具有较强的抗光漂白性,可调的发光性能,低毒性和良好的生物相容性而引起研究者的极大兴趣。合成CDs的方法主要包括自上而下法和自下而上法。传统合成方法所制备的裸CDs由于量子产率较低,CDs形成机制不明确,应用也受到一定限制。合成过程中或合成后的修饰可有效提高CDs的量子产率和荧光性能,从而拓宽其在生物成像、探针、光催化剂、生物药物载体、光电材料等领域的应用。本文将对近年来有关CDs的几种修饰方法:形成金属纳米粒子-CDs复合物、杂原子掺杂和表面功能化的理论研究及应用加以综述,并对当前需要解决的问题以及今后的研究发展方向进行了探讨。     

荧光碳点在分析传感中的应用进展

荧光碳点（CDs）是2004年发现的一种新型碳基纳米材料,呈球形、粒径在2～10 nm左右,具有优异的荧光性能、易于功能化修饰、抗光漂白性强、环境危害低、生物相容性好以及合成原料来源丰富等特点,被认为是有机荧光染料和半导体量子点的最佳替代品,在光电学、光催化、化学传感和生物成像等领域有着广阔的应用前景。本文主要介绍了CDs作为化学传感器的荧光检测机制,重点总结了近年来CDs在离子、有机小分子以及生物大分子检测等方面的应用,以期为荧光纳米探针的设计与应用提供理论和研究依据。     

叶酸修饰的碳量子点在体外癌细胞成像中的应用

具有癌细胞靶向性的荧光纳米探针在生物分析、生物医学和临床诊断等领域有着重要的应用前景。 本文基于碳量子点的低毒性、低成本、环境友好、制备方法简单及高发光特性等优点,采用水热法合成了表面富含氨基的荧光碳量子点(CDs),进一步通过1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)缩合的方法,将叶酸(FA)分子中的羧基与其共价连接,从而得到叶酸共价修饰的碳量子点复合材料(FA-CDs)。 通过将该复合材料分别与海拉(Hela)和小鼠胚胎成纤维(NIH-3T3)细胞共培养,发现该复合材料能够特异性识别并标记癌细胞,且制备的该复合材料具有低毒性和高发光性等优点。 该工作对癌细胞的早期诊断具有重要意义。     

碳点基水相室温磷光复合材料研究进展

室温磷光(RTP)凭借较长的发光寿命和强烈的环境敏感特性,在化学/生物传感、生物成像、高级光学防伪与信息加密等诸多领域表现出广阔的应用前景。近些年,具有制备简单、化学惰性、低毒性、易功能化等优势的固态非金属室温磷光碳点获得了研究者的青睐。然而,其磷光发射易受水环境中溶解氧和水分子影响而淬灭,导致其应用局限于固态基质(如防伪油墨)。因而,如何稳定水相下碳点的激发三重态是实现其RTP发射与应用的关键。本文依据近年来碳点基水相RTP复合材料的最新研究进展,归纳总结了其构建策略及在传感、成像及防伪等方面的应用,并探讨了其面临的挑战及未来的发展方向。     

基于共价有机框架的电化学生物传感器在生物样品检测中的应用

共价有机框架材料(Covalent Organic Frameworks, COFs)是一种具有纳米级结构有序性的二维或三维有机结晶材料, 具有高度周期性和可修饰性等结构优点. 基于COFs制备的电化学生物传感器具有灵敏度高、特异性强、重复性好等特点, 在检测生物样品方面具有广阔前景. 本综述简要概述了COFs的合成方法与策略、电化学生物传感器的介绍与分类以及COFs在电化学生物传感检测生物样品领域的应用. 最后本综述对COFs材料在生物传感领域的技术瓶颈与未来的发展方向进行了总结与讨论.     

基于石墨烯功能复合材料的DNA电化学生物传感器

石墨烯(Gr)是一类由单层碳原子组成的二维碳质材料,利用它独特的结构和良好的物理、化学性能,可构筑出在电催化、电化学传感器和生物传感器等领域有着巨大应用潜力的新型Gr功能复合材料。基于Gr功能复合材料的DNA电化学传感器与常规DNA传感器相比,具有明显的特色和优势,已被应用于特异DNA靶序列的识别和传感领域。本文就基于Gr功能复合材料的DNA电化学传感器的近期进展作简要评述,包括Gr与Gr基金属、金属氧化物、高分子、生物分子复合材料的电化学性能及其在DNA电化学传感中的应用,并对该类DNA电化学传感器的发展方向和应用前景进行了展望。     

碳量子点激发依赖荧光特性的机理、调控及应用

碳量子点（carbon dots,CDs）是一种具有强荧光、荧光波长可调、无光漂白等特性的新型荧光纳米粒子,其制备简单、成本低,而且具有良好的生物相容性和低毒性,在光电器件、生物传感及药物载体等领域展现出广阔的应用前景。其具有的独特激发依赖荧光特性是指随着激发波长的改变,其发射波长将随之改变,所以,通过调节激发波长即可实现CDs的连续全色发射,可为其在多色成像生物领域提供可能性。此外,在长波长激发下,CDs发射波长甚至可以延续到近红外区域,展现出在活体成像领域的应用前景。因此,探索CDs激发依赖荧光特性的机理是非常重要的,这将为实现CDs的激发依赖荧光特性提供理论指导。本文就近年来人们对于CDs激发依赖荧光特性的研究进行了综述,重点概述了CDs激发依赖荧光特性的机理、调控实现CDs激发依赖荧光特性的方法及CDs激发依赖荧光特性的应用。目前,CDs激发依赖荧光特性的机理主要包括：不同表面态的分布、宽的尺寸分布、碳核结构的存在及周围慢的溶剂弛豫;实现CDs激发依赖荧光特性的方法主要有：对表面态的控制、尺寸分布的控制及碳核结构的控制;CDs激发依赖荧光特性的应用主要表现在细胞成像和光电器件。最后,对这一特性研究中尚存在的问题进行了总结并且展望了其发展前景。     

Synthesis of highly luminescent carbon dots from postconsumer waste silk cloth and investigation of its electron transfer dynamics with methyl viologen dichloride

Synthesis of luminescent carbon dots (CDs) from biological waste materials is gaining more attention in the present-day scenario. We have synthesized highly luminescent (luminescence quantum yield, φ ​= ​19.1%), water-soluble CDs from a postconsumer waste silk cloth via a facile hydrothermal synthetic method. The resulting CDs are characterized and their photophysical properties are studied in detail. The electron transfer dynamics of CDs in presence of methyl viologen dichloride hydrate (MV²⁺) is systematically investigated in this work. Knowledge of the electron transfer dynamics of CDs is essential in the structural elucidation of CDs, prediction of sensing mechanisms and utilizing the CDs in energy storage devices.     

Red,green and blue aggregation‐induced emissive carbon dots

As one of the most promising fluorescent nanomaterials, carbon dots (CDs) have been extensively studied for their fluorescent properties in solution. However, research on the synthesis of multicolor solid-state fluorescence (SSF) CDs (from blue to red) is rarely reported. Herein, we used o-phenylenediamine, m-phenylenediamine and p-phenylenediamine with dithiosalicylic acid (DTSA) in the solvothermal reaction using acetic acid as a solvent to obtain aggregation-induced emissive (AIE) CDs of red (620 nm), green (520 nm), and blue (478 nm), respectively. XPS spectra and TEM image show that with the red-shift of luminescence, the particle size and content of C=O of the CDs gradually increases. Finally, based on the non-matrix solid-state multicolor luminescence characteristics of CDs, the application of white light LED devices is realized. Besides, based on the fat-soluble properties of CDs, fingerprint detection applications are realized.     

Analytical and bioanalytical applications of carbon dots

Carbon dots (CDs) comprise a recently discovered class of strongly fluorescent, emission-color-tuning and non-blinking nanoparticles with great analytical and bioanalytical potential. Raw CDs can be obtained by laser ablation or electrochemical exfoliation of graphite, from soot, or thermal carbonization, acid dehydration or ultrasonic treatment of molecular precursors. Passivation of raw CDs makes them fluorescent and their functionalization confers reactivity towards selected targets. CDs can be excited by single-photon (ultraviolet or near-ultraviolet) and multi-photon (red or near-infrared) excitation, and their luminescence properties are due to surface defects. CDs are being proposed as bioimaging probes because they comprise non-toxic elements and are biocompatible. Passivated and functionalized CDs can be made to sense pH, metal ions and molecular substances.     

碳点在抗生素分析检测中的应用

抗生素的过度使用对环境造成了极大破坏,对其进行监测控制刻不容缓。常用的分析检测技术,如高效液相色谱(HPLC)、气相色谱(GC)、高效液相色谱-串联质谱(HPLC-MS/MS)等具有高效快速、重现性好、可自动化操作等优点。但对环境样品中抗生素的检测存在样品前处理过程繁琐、检测灵敏度低、实验成本高等问题。结合现有的检测技术发展新型材料,对提高抗生素的检测灵敏度具有重要意义。碳点(CDs)是一种尺寸介于0~10 nm之间的新型纳米材料,具有小尺寸效应、优异的电学和光学性质、良好的生物相容性等优点,已被广泛应用于环境样品中抗生素的检测。该综述对近5年CDs与传感器、色谱分析技术结合检测抗生素的应用进行了总结,并对其发展前景进行了展望。该文总结了CDs与分子印迹传感器、适配体传感器、电化学发光传感器、荧光传感器及电化学传感器相结合,及其在抗生素检测中的应用;对涉及的比率型传感器、阵列传感器等先进分析方法进行了举例评述;对CDs作为色谱固定相分离抗生素进行了阐述。文献表明,CDs结合传感器检测抗生素可有效提高检测灵敏度,但对复杂环境样品中抗生素的检测还面临着构建高选择性传感器、开发新型材料及数据处理等方面的挑战;目前,CDs作为色谱固定相对抗生素的材料分离,仍处于初步研究阶段,分离机理尚不明确,有待进一步深入研究。总之,CDs在环境样品中抗生素的检测方面仍面临一系列问题,随着人们对CDs的深入研究以及各种分析检测技术的不断发展,CDs将会在抗生素等环境污染物的检测中发挥重要作用。     

Red,Green, and Blue Luminescence by Carbon Dots: Full‐Color Emission Tuning and Multicolor Cellular Imaging

A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet‐light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up‐conversion (UC)PL of these CDs is also observed. Moreover, flexible full‐color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light‐emitting diodes, full‐color displays, and multiplexed (UC)PL bioimaging.     

Red,Green, and Blue Luminescence by Carbon Dots: Full‐Color Emission Tuning and Multicolor Cellular Imaging

A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet‐light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up‐conversion (UC)PL of these CDs is also observed. Moreover, flexible full‐color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light‐emitting diodes, full‐color displays, and multiplexed (UC)PL bioimaging.     

Study and Comparison on Purification Methods of Multicolor Emission Carbon Dots

Recent years have witnessed a rapid development of carbon dots (CDs), due to their outstanding luminescence properties and excellent biocompatibility. However, the internal structure and photoluminescent (PL) mechanism of CDs are still the subject of considerable debate, which is due to the fact that reaction products usually contain mixtures of several CD fractions as well as molecular intermediate and side products. Therefore, careful purification of the CDs is significant for analysis of structure and luminescence mechanism. Here, multicolor emission CDs were prepared by a one-pot pyrolysis of citric acid in formamide. Then, the precipitation method, dialysis and gel permeation chromatography (GPC) are successively employed to purify the multicolor emission CDs. This post-treatment allowed us to compare the optical properties of CDs obtained by different separation methods and provide a valuable guidance for the purification of CDs.     

Synthesis of photoluminescent carbogenic dots using mesoporous silica spheres as nanoreactors

A novel and facile approach for preparing hydrophilic carbogenic dots (CDs) has been developed with mesoporous silica spheres as nanoreactors by using an impregnation method. The resulting highly efficient photoluminescent CDs without any further treatment are monodisperse, photostable and of low toxicity, and show excellent luminescence properties.     

Rapid and Large‐Scale Production of Multi‐Fluorescence Carbon Dots by a Magnetic Hyperthermia Method

The intrinsic low yield of carbon dots (CDs) is a barrier that limits practical application. Now, a magnetic hyperthermia (MHT) method is used to synthesize fluorescent CDs on a large scale (up to 85 g) in one hour (yield ca. 60 %). The reaction process is intensified by MHT since the efficient heating system enhances the energy transfer. CDs with blue, green, and yellow luminescence are synthesized by using carbamide and citrate with three different cations (Zn²⁺, Na⁺, K⁺), respectively. The CDs exhibit bright fluorescence under UV light and show excellent monodispersity and solubility in water. The alternation of photoluminescence (PL) emissions of these CDs is probably due to the difference in particle sizes and surface state. A bar coating technique is used to construct large‐area emissive polymer/CDs films. CDs can insert themselves into the polymer chains by hydrogen bonding and electrostatic interactions. Wound healing efficiency can be enhanced by the Zn‐CDs/PCL nanofibrous scaffold.     

Circularly Polarized Luminescence of Achiral Carbon Dots in Bi-Solvent Systems Triggered by Supramolecular Self-Assembly

An innovative strategy for circularly polarized luminescence (CPL) of carbon dots (CDs) has been developed: The achiral CDs displayed contrary supramolecular chirality and opposite CPL in two different bi-solvent systems, which are due to the formation of self-assembled helical nanostructures with two diverse assembly modes (P and M) in aggregate state via intermolecular π-π interactions and differential hydrogen bonding (H-bonding) without the need of any additional element of chirality.