碳基量子点荧光传感器在环境检测中的应用研究

由于优越的光学性能、良好的水溶性及生物相容性,碳基量子点在荧光传感器方面的应用引起了越来越多人的关注,特别是对金属离子卓越的检测性能使其广泛应用于环境检测。为了帮助更好地了解到碳基量子点的应用,本文对碳量子点、石墨烯量子点、氧化石墨烯量子点的合成及其在环境检测中的应用进行总结,并对碳基量子点荧光传感器的应用进行展望。     

碳点的设计合成、结构调控及应用

碳点是一类环境友好且性能独特的纳米粒子, 在光电转换、 生物医学、 催化及储能等领域的研究日益活跃. 碳点主要分为碳量子点(CQDs)、 石墨烯量子点(GQDs)和碳化聚合物点(CPDs), 其中CPDs作为一种新型碳点, 具有合成原料广泛、 碳化程度及共轭结构可调且材料相容性好等优点. 本文综合评述了近年来碳点尤其是CPDs的合成方法; 阐述了通过选择前驱体分子、 控制反应条件及掺杂原子等手段实现对其碳化和共轭程度、 晶格和能级结构的调控, 从而建立碳点及其杂化与复合材料微纳结构与性能之间的关系; 最后, 介绍了碳点在生物标记与成像、 光(电)催化、 光电转换及储能等领域的应用, 并对碳点领域的发展前景进行了展望.     

荧光碳点的合成、性质和应用

与传统半导体发光材料相比,荧光碳点作为一种新型的碳纳米发光材料,因其优异的生物相容性、良好的发光性能、简单的合成工艺、低廉的成本等优点而备受关注。荧光碳点在生物荧光标定、医学传感器、光诊疗剂以及发光器件等方面具有广阔的应用潜力。本文重点阐述了荧光碳点的合成方法、显微结构分析、荧光机理及应用的最新成果,希望为荧光碳点合成与应用研究的发展提供参考。     

发光碳量子点的合成、性质和应用

基于碳量子点具有良好的水溶性、化学惰性、低毒性、易于功能化和抗光漂白性等优异性能,碳量子点和其它的碳纳米材料（如富勒烯、碳纳米管和石墨烯等）同样引起了研究者广泛的关注。 碳量子点可以通过很多较为廉价的一步法进行大规模的制备,包括化学氧化法、超声法、微波法和激光烧蚀法等。 本文主要介绍了不同碳量子点的合成方法,以及依赖于碳量子点尺寸和波长等性质的发光性能,并且讨论了碳量子点在生物成像、光催化、能量转换/储存、光电子、光限幅和传感器等方面的应用。     

Polymer carbon dots—a highlight reviewing their unique structure,bright emission and probable photoluminescence mechanism

In recent years, a novel fluorescent material, carbon dots (CDs), is becoming a hot topic. Recent research works found that some types of CDs with high quantum yield are mainly composed of polymer structures or polymer/carbon hybrid structures rather than the pure carbon/graphite structure. These types of CDs, named as polymer carbon dots (PCDs) here, are drawing growing interests due to the designed hybrid structure and functional integration. Typically, PCDs are nano-sized particles possessing abundant polymer structures with low carbonization degree, prepared from the monomers or non-conjugated polymers by condensation, crosslinking, assembling, or slightly carbonization processes. In this highlight, we bring up the new concept of PCDs and discuss the relationships among non-conjugated polymer, PCDs and CDs, demonstrating that the possible fluorescence mechanism of PCDs is inferred as crosslink enhanced emission effect. Furthermore, the structure, properties, and synthetic methods of the reported typical PCDs were summarized and prospected. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 610–615     

Highly luminescent N,S- Co-doped carbon dots and their direct use as mercury(II) sensor

Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg²⁺ complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg²⁺ is manufactured for the evaluation of usage of NSCDs in the real circumstance.     

Facile one-pot synthesis of PEG-derived carbon dots with enhanced luminescence via L-cysteine-assisted S,N-doping

Carbon nanodots (C-dots) are promising photoluminescent nanomaterials for biomedical applications. Among them, PEG-derived C-dots demonstrate exceptional photoluminescence and passivation properties, making them particularly attractive for use in the biomedical field. In this article, we present the synthesis of photoluminescent S,N-doped PEG-derived carbon dots that are stable at ambient temperature and can be produced using an easy hydrothermal technique. To synthesize the carbon dots, the non-hazardous polymer polyethylene glycol (PEG) was used as the sole precursor rather than any other potentially hazardous compounds. The absence of L-cysteine in the reaction mixture resulted in carbon dots with no significant absorbance in the visible region but exhibited photoluminescence properties with a maximum excitation and emission at 343 and 452 nm, respectively. However, the addition of L-cysteine resulted in a visible absorbance and a red shift in both the maximum excitation and emission, at around 435 and 503 nm, respectively. The Fourier transform infrared spectroscopy (FTIR) analysis provided evidence for the presence of -SH, -SO₂, -NH₂, and CON-H bond stretching after the addition of L-cysteine, suggesting possible S,N-doping of the carbon dots, which likely caused the observed changes in photoluminescence properties. These findings contribute to the understanding of S,N-doping in carbon dots and highlight their potential applications in optoelectronics, sensing, and biomedical imaging.     

基于头孢他啶测定的CQDs内标型比率荧光探针的构建

以天然生物质蒲公英为碳源,加入乙二胺,通过一步水热法合成氨基化蒲公英碳量子点(DE-CQDs).该DE-CQDs可与罗丹明6G(Rh6G)通过静电吸附作用形成具有特征双发射信号的DE-CQDs/Rh6G复合物.单一激发波长343 nm下,BR缓冲溶液pH 3.0时,复合物DE-CQDs/Rh6G于425 nm和550 ...     

由蚕砂制备的碳量子点在不同激发、pH、金属离子、温度及极性环境下的荧光性质研究

碳量子点作为一种新兴的荧光纳米材料,具有粒径分布均匀、光稳定性好、激发-发射波长可调控、表面可修饰等优良的性质,兼具低毒性、生物相容性好等优点,在分析检测和生物成像等领域展现出广阔的应用前景。而蚕砂是家蚕的干燥粪便,简单易得。利用蚕砂作为碳量子点制备原料,采用微波合成的方法制备得到了一种平均水合粒径为4.86 nm,含氮、硫修饰的碳量子点材料,可作为针对激发波长、pH、金属离子浓度、温度及溶剂极性的变化有着显著响应特性的碳量子点型荧光探针。该探针的荧光最大发射波长随激发波长或pH的增加而红移;荧光强度随温度或pH的降低而增加;随着金属离子,特别是铜离子的加入而逐渐降低,并随着EDTA络离子的加入而逐渐回复。在多种溶剂中该探针均具有较好的溶解度,当换用不同极性的溶剂时,随着溶剂极性的增加荧光发射波长逐渐红移。荧光性质随多重环境参数变化为该碳量子点在未来的生物检测和成像领域提供了广阔的应用前景。     

Carbon Dots (C‐dots) from Cow Manure with Impressive Subcellular Selectivity Tuned by Simple Chemical Modification

Improved cellular selectivity for nucleoli staining was achieved by simple chemical modification of carbon dots (C‐dots) synthesized from waste carbon sources such as cow manure (or from glucose). The C‐dots were characterized and functionalized (amine‐passivated) with ethylenediamine, affording amide bonds that resulted in bright green fluorescence. The new modified C‐dots were successfully applied as selective live‐cell fluorescence imaging probes with impressive subcellular selectivity and the ability to selectively stain nucleoli in breast cancer cell lineages (MCF‐7). The C‐dots were also tested in four other cellular models and showed the same cellular selection in live‐cell imaging experiments.     

Functionalized Carbon Nanoparticles,Blacks and Soots as Electron‐Transfer Building Blocks and Conduits

Functionalized carbon nanoparticles (or blacks) have promise as novel active high‐surface‐area electrode materials, as conduits for electrons to enzymes or connections through lipid films, or as nano‐building blocks in electroanalysis. With previous applications of bare nanoblacks and composites mainly in electrochemical charge storage and as substrates in fuel cell devices, the full range of benefits of bare and functionalized carbon nanoparticles in assemblies and composite (bio)electrodes is still emerging. Carbon nanoparticles are readily surface‐modified, functionalized, embedded, or assembled into nanostructures, employed in bioelectrochemical systems, and incorporated into novel electrochemical sensing devices. This focus review summarizes aspects of a rapidly growing field and some of the recent developments in carbon nanoparticle functionalization with potential applications in (bio)electrochemical, photoelectrochemical, and electroanalytical processes.     

Convenient Determination of Sulfamethazine in Milk by Novel Ratiometric Fluorescence with Carbon and Quantum Dots with On-site Naked-eye Detection and Low Interferences

Sulfamethazine, one of the most widely applied feed additives, has been shown to cause negative health effects to humans. In the present work, a novel and facile fluorescence visual detection probe was established to determine sulfamethazine in milk samples with naked-eye detection. Considering the good stability, excellent optical properties, and easy synthesis, blue-emission carbon dots were used as the standard signal and red-emission CdTe quantum dots as the responsive signal for the determination of sulfamethazine. The fluorescence intensity of red-emission CdTe quantum dots was gradually quenched with increasing concentration of sulfamethazine, while the blue-emission carbon dots response remained constant. Apparent color variations were observed by naked-eye detection in the concentration range from 9.0 to 54?µmol?·?L^?1. In addition, the presented strategy was shown to be promising to provide a rapid, facile, and sensitive method for the determination of sulfamethazine in milk samples with few interferences.     

碳点的性质及其在化学发光分析中的研究进展

碳点是一种新型的荧光碳纳米颗粒,与传统的半导体量子点相比,碳点具有毒性低、生物相容性好、原料丰富廉价、光稳定性好等特点,得到引了化学、材料和生物等各领域科学家的高度关注。 本文介绍了碳点的基本概念和性质、探讨了碳点在化学发光领域的应用研究进展并进行了展望。     

Highly conjugated water soluble CdSe quantum dots to multiwalled carbonnanotubes

Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.     

硫酸钡粒径调控剂C-N-CDs的制备、应用及机理

通过柠檬酸与乙二胺水热反应制备羧基、氨基修饰碳点(C-N-CDs),其具有优异的硫酸钡粒径调控作用：可使沉淀法制备的BaSO₄颗粒平均粒径减小到45.3 nm,小于同等条件下传统配位剂乙二胺四乙酸(EDTA)调控制备的BaSO₄颗粒平均粒径(73.7nm)。将所制备的纳米BaSO₄样品添加进聚乙烯醇(PVA)薄膜中可增强薄膜的力学性能。研究发现C-N-CDs的化学性能、表面电性、空间位阻是影响BaSO₄粒径大小的重要因素。     

Bottom-Up Synthesis,Dispersion and Properties of Rectangular-Shaped Graphene Quantum Dots

Carbon nanomaterials have attracted the attention of the scientific community for more than 30 years now; first with fullerene, then with nanotubes and now with graphene and graphene related materials. Graphene quantum dots (GQDs) are nanoparticles of graphene that can be synthesized following two approaches, namely top-down and bottom-up methods. The top-down synthesis used harsh chemical and/or physical treatments of macroscopic graphitic materials to obtain nanoparticles, while the second is based on organic chemistry through the synthesis of polycyclic aromatic hydrocarbons exhibiting various sizes and shapes that are perfectly controlled. The main drawback of this approach is related to the low solubility of carbon materials that prevents the synthesis of nanoparticles containing more than few hundreds of sp² carbon atoms. Here we report on the synthesis of a family of rectangular-shaped graphene quantum dots containing up to 162 sp² carbon atoms. These graphene quantum dots are not functionalized on their periphery in order to keep the maximum similarity with nanoparticles of pure graphene. We chose water with sodium deoxycholate surfactant to study their dispersion and their optical properties (absorption, photoluminescence and photoluminescence excitation). The electronic structure of the particles and of their aggregates are studied using Tight-Binding (TB). We observe that the larger particles ( GQD 3 and GQD 4 ) present a slightly better dispensability than the smaller ones, probably because the larger GQDs can accommodate more surfactant molecules on each side, which helps to stabilize their dispersion in water.     

Photoactivated Fluorescence Enhancement in F,N‐Doped Carbon Dots with Piezochromic Behavior

Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co‐doped carbon dots (F,N‐doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N‐doped CDs increases with UV light irradiation (5 s–30 min), accompanied with a blue‐shift of the fluorescence emission from 586 nm to 550 nm. F,N‐doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N‐doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure‐triggered aggregation‐induced emission in the range 1.0 atm–0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high‐pressure conditions and enhances their anti‐photobleaching.     

超声法一步合成生物相容的黄绿色荧光碳点

本文以蜡烛灰为碳源,在强酸环境中超声法一步合成了粒径均匀的荧光碳点（CDs）,粒径（3.47±1.81）nm,在紫外灯照射下发出黄绿色荧光.研究表明,CDs表面带有-OH、C=O和-COOH等官能团,存在sp3杂化和sp2杂化两种碳原子.所合成的碳点具有良好的耐光漂白能力和生物相容性,能潜在地作为黄绿色荧光成像试剂应用于细胞成像.     

氟化修饰显著提高碳点的抗菌活性

本文采用支化聚乙烯亚胺和乙醇制备阳离子碳点,并在其表面接枝含氟烷基链,得到一种氟化修饰的碳点材料,其对革兰氏阳性菌金黄色葡萄球菌以及革兰氏阴性菌大肠杆菌和绿脓杆菌都表现出了优异的抗菌活性,而对哺乳动物细胞具有较低的毒性。通过构效关系研究发现,氟化修饰对于碳点的抗菌活性至关重要,将含氟烷基链替换成烷烃基链会极大削弱碳点的抗菌性能。本文的结果为阳离子抗菌材料的设计提供了新的思路。     

Carbon Dots for Carbon Dummies: The Quantum and The Molecular Questions Among Some Others

Carbon Dots (CDs) are carbon nanoparticles which were discovered in 2004. Despite two decades of intensive work from the scientific community and a colossal amount of gathered experimental data, no definitive consensus exists to date on several key aspects such as the actual definition of CDs and the origin of their emissive properties. This review proposes a critical evaluation of these fundamental questions. Lay persons will also find here an alternative introduction to the CDs domain, including synthetic strategies, photophysical properties, as well as challenges and outlook of this exciting new area.