制备条件对PEI功能化石墨烯量子点荧光性能的影响（英文）

石墨烯量子点凭借其良好的水溶性、低生物毒性等特点,被不断尝试应用于生物成像领域,但其有限的荧光性能限制了其进一步应用。为改善石墨烯量子点的荧光性能以及进一步揭示石墨烯量子点的制备机理,本文对聚乙烯亚胺(PEI)功能化石墨烯量子点的制备条件进行了探索,讨论了不同反应时间、制备温度以及混悬液p H值对其荧光性能的影响。测试结果显示,当混悬液p H值为12时,在反应釜中经过200°C高温反应20 h,所制备的功能化石墨烯量子点能取得良好的紫外吸收峰和荧光性能,同时达到较高的量子产量。     

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。     

蛋氨酸功能化石墨烯量子点pH传感性能及应用

分别以柠檬酸和蛋氨酸为碳源和功能化前驱体,采用高温热解法制备新型蛋氨酸功能化石墨烯量子点(Met-GQDs)。Met-GQDs具有石墨烯类似的晶体结构,平均粒径为3 nm,氮、硫元素成功掺入到石墨烯量子点中。相对于仅由柠檬酸制备的石墨烯量子点,Met-GQDs表现出更好的荧光强度和光稳定性,表明蛋氨酸功能化基团的引入能明显改善石墨烯量子点的光学性质。基于Met-GQDs荧光对环境pH的灵敏响应,建立了检测pH的分析方法。当pH在1~14之间,Met-GQDs的荧光强度随p H的增加而线性增大。方法在灵敏度和pH响应范围方面优于文献报道的光学传感器,已成功应用于环境水样中pH快速检测和细胞成像。     

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。     

双功能石墨烯量子点的制备及在pH荧光检测和细胞成像中的应用

为改善石墨烯量子点的光学性质,设计并合成了五乙烯六胺和十二胺功能化石墨烯量子点(PEHAGQD-DA)。将柠檬酸和五乙烯六胺混合,170℃热解0.5 h后加入十二胺,继续反应1.5 h得到PEHA-GQDDA。PEHA-GQD-DA由尺寸仅为1~3 nm的石墨烯片组成,片边缘含有丰富的功能基团。五乙烯六胺的引入显著提高了量子点的荧光发射,荧光量子产率达到72.7%,明显高于单独柠檬酸热解所制备的石墨烯量子点。引入十二胺,使PEHA-GQD-DA容易通过细胞膜磷脂双分子层进入到细胞内部。PEHA-GQD-DA对环境pH值表现出极佳的光学响应行为。在pH 1.0~6.5时,荧光强度随pH值增加而线性增强。随pH值的变化,荧光光谱也发生改变,最大发射波长与pH值之间存在良好的线性关系。在pH 6.5~12.0时,荧光光谱不再随pH值变化而变化,但荧光强度随pH值增大而线性减少。常见无机离子和小分子化合物不影响PEHA-GQDDA对pH值的荧光响应。PEHA-GQD-DA已成功应用于环境水样pH值的荧光检测和Hela细胞成像。     

一锅法高效制备橙色荧光氧化石墨烯量子点及其在细胞pH成像中的应用

以价廉、易得的石墨片为原料,采用改进的Hummers法,简单、快速、高效地制备了具有良好生物相容性的橙色荧光氧化石墨烯量子点(GOQDs)。所制备的GOQDs尺寸约7.2 nm,具有尺寸均匀、晶格间距为0.20 nm的高度结晶的核心和氧化的外围结构。与大多数报道的碳点(CDs)、包裹掺杂碳点(掺杂 CDs)、石墨烯量子点(GQDS)和 GOQDs不同,我们的方法制备的 GOQDs显示出橙红色并具有激发波长独立的荧光发射。此外,GOQDs具有pH依赖性荧光发射、强的光漂白抗性、低细胞毒性、良好的水溶性(ρ=10 mg·mL^-1)和优异的生物相容性。这些特性使其成功应用于细胞pH成像。     

一锅法高效制备橙色荧光氧化石墨烯量子点及其在细胞pH成像中的应用

以价廉、易得的石墨片为原料,采用改进的Hummers法,简单、快速、高效地制备了具有良好生物相容性的橙色荧光氧化石墨烯量子点(GOQDs)。所制备的GOQDs尺寸约7.2 nm,具有尺寸均匀、晶格间距为0.20 nm的高度结晶的核心和氧化的外围结构。与大多数报道的碳点(CDs)、包裹掺杂碳点(掺杂CDs)、石墨烯量子点(GQDS)和GOQDs不同,我们的方法制备的GOQDs显示出橙红色并具有激发波长独立的荧光发射。此外,GOQDs具有pH依赖性荧光发射、强的光漂白抗性、低细胞毒性、良好的水溶性(ρ=10 mg·mL^-1)和优异的生物相容性。这些特性使其成功应用于细胞pH成像。     

氨基功能化石墨烯量子点表面缺陷钝化及其发光增强

通过酸氧化法将氧化石墨烯进一步“切割”制备石墨烯量子点（GQDs）,在100℃水热条件下,用氨水处理石墨烯量子点制备得到氨基功能化石墨烯量子点（N-GQDs）。傅里叶变换红外光谱证明NH₃可以有效地进攻环氧基碳和羧基碳,形成羟胺和酰胺基。原子力显微镜结果表明NH₃不仅能够有助于产生更小的量子点,还对石墨烯纳米片有致孔作用。氨基功能化之后,由于C-O-C相关的n-π^*跃迁受到抑制,N-GQDs发光具有更弱的激发波长依赖性,并使其荧光量子产率从0.3%提高至9.6%。时间分辨发光光谱表明,相比含氧基团,含氮基团相关的局域电子激发态具有更长的荧光寿命和更弱的发射光谱依赖性。     

ZnO-离子液体功能化的石墨烯量子点的制备及荧光性能

利用水热法制备了ZnO-1-丙胺基-3-甲基咪唑氯离子液体功能化的石墨烯量子点溶液,通过紫外-可见吸收光谱、红外吸收光谱和透射电镜对其进行了表征.通过研究各种因素对ZnO-离子液体功能化的石墨烯量子点的荧光发射光谱的影响,发现Cr_2O_7~(2-)对ZnO-离子液体功能化的石墨烯量子点有荧光猝灭现象.实验结果表明,在优化的实验条件下,pH=5.0,Cr(Ⅵ)浓度为1.0×10~(-7)～1.6×10~(-6 )mol·L~(-1)时,Cr(Ⅵ)对ZnO-离子液体功能化的石墨烯量子点的荧光猝灭呈线性,其线性方程为F/F_0=0.969 5-0.008 4c,R=0.998 8,检出限为7.6×10~(-2)μmol·L~(-1).     

绿色、低成本球磨-水热法制备石墨烯量子点及其应用研究

以绿色、简单、成本低的球磨方法制备的石墨烯为碳源,采用一步水热法成功制备了分散性好、尺寸分布均一、平均直径为(4.80 ± 0.20) nm、厚度为1~3层石墨烯烯量子点.分别采用高分辨透射电镜、原子力显微镜、傅里叶变换红外光谱、X射线光电子能谱、紫外-可见吸收光谱、荧光光谱等对石墨烯量子点进行形貌、结构以及荧光性能的表征. 合成的石墨烯量子点可用于Fe.3+的非标记、特异性检测,检测线性范围为2.0×10.-6~7.0×10.-4 mol/L,检出限为1.8×10.-6 mol/L(S/N=3),同时对检测机理进行了推断,证明此石墨烯量子点用于自来水中Fe.3+的检测的可行性;基于其低毒性和优良的生物相容性,所制备的石墨烯量子点可应用于细胞成像研究.本研究为碳纳米材料的制备提供了一种新途径,也为石墨烯量子点在生化分析、成像等方面的研究奠定了基础.     

一锅溶剂热法制备具有不同形貌特征的CdSe量子点负载石墨烯

利用Hummer氧化法制备了氧化石墨烯,并对氧化石墨烯的NaBH₄化学还原法和乙二胺溶剂热还原法进行了比较,发现用乙二胺还原后可在石墨烯表面引入含氮基团,增加片层间的距离,提高分散性。采用乙二胺溶剂热还原法,发展了一锅法制备CdSe量子点负载石墨烯的简易方法。对CdSe量子点负载石墨烯的表征分析结果显示,氧化石墨烯在负载CdSe量子点的同时自身被还原,氧含量显著减少,而还原后的石墨烯表面引入了含氮基团。考察了反应温度及反应时间的影响,研究结果表明,反应温度的变化对氧化石墨烯的还原过程影响不大,而反应时间的影响相对明显。随着反应时间的延长,石墨烯的还原程度越高,石墨烯表面负载的CdSe则由量子点由颗粒逐渐长大成为纳米棒和支化的星状纳米结构。通过调控反应条件可在控制氧化石墨烯还原程度的同时改变石墨烯表面所负载CdSe量子点的形貌,这为形貌可控的CdSe量子点负载石墨烯的制备提供了一种有效方法。     

一锅溶剂热法制备具有不同形貌特征的CdSe量子点负载石墨烯

利用Hummer氧化法制备了氧化石墨烯,并对氧化石墨烯的NaBH4化学还原法和乙二胺溶剂热还原法进行了比较,发现用乙二胺还原后可在石墨烯表面引入含氮基团,增加片层间的距离,提高分散性。采用乙二胺溶剂热还原法,发展了一锅法制备CdSe量子点负载石墨烯的简易方法。对CdSe量子点负载石墨烯的表征分析结果显示,氧化石墨烯在负载CdSe量子点的同时自身被还原,氧含量显著减少,而还原后的石墨烯表面引入了含氮基团。考察了反应温度及反应时间的影响,研究结果表明,反应温度的变化对氧化石墨烯的还原过程影响不大,而反应时间的影响相对明显。随着反应时间的延长,氧化石墨烯的还原程度越高,石墨烯表面负载的CdSe量子点则由颗粒逐渐长大成为纳米棒和支化的星状纳米结构。通过调控反应条件可在控制氧化石墨烯还原程度的同时改变石墨烯表面所负载CdSe形貌,这为形貌可控的CdSe量子点负载石墨烯的制备提供了一种有效方法。     

Analytical applications of nanomaterials in electrogenerated chemiluminescence

This critical review covers the use of carbon nanomaterials (single-wall carbon nanotubes, multi-wall carbon nanotubes, graphene, and carbon quantum dots), semiconductor quantum dots, and composite materials based on the combination of the aforementioned materials, for analytical applications using electrogenerated chemiluminescence. The recent discovery of graphene and related materials, with their optical and electrochemical properties, has made possible new uses of such materials in electrogenerated chemiluminescence for biomedical diagnostic applications. In electrogenerated chemiluminescence, also known as electrochemiluminescence (ECL), electrochemically generated intermediates undergo highly exergonic reactions, producing electronically excited states that emit light. These electron-transfer reactions are sufficiently exergonic to enable the excited states of luminophores, including metal complexes, quantum dots and carbon nanocrystals, to be generated without photoexcitation. In particular, this review focuses on some of the most advanced and recent developments (especially during the last five years, 2010–2014) related to the use of these novel materials and their composites, with particular emphasis on their use in medical diagnostics as ECL immunosensors.     

Synthesis and characterization of mondispersed CdSe nanocrystals at lower temperature

Nearly monodispersed CdSe quantum dots have been prepared by a soft solution approach using air-stable reagents at lower temperature. The temporal evolution of the absorption and room temperature photoluminescence spectra were used to follow the reaction process and to characterize the optical properties of as-prepared CdSe quantum dots. The results exhibited clear exciton peaks in absorption and bright band-edge luminescence. The structures of the CdSe nanocrystals were determined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The influence of the temperature on the properties of the resultant CdSe nanocrystals was investigated. The distribution of properties within ensembles of CdSe nanocrystals was also studied. A drastic difference in the photoluminescence efficiencies of size-selected fractions was observed.     

巯基乙酸为稳定剂在MWCNTs上原位生长CdSe量子点

以巯基乙酸作为稳定剂在无毒的溶剂中和较低的温度下实现了CdSe量子点在MWCNTs（多壁碳纳米管）上的原位生长,并用TEM、HRTEM、EDS、XRD、XPS和PL等工具对CdSe量子点-MWCNTs异质结（CdSe-MWCNTs）进行了表征.结果表明, CdSe量子点的晶型为立方晶型,平均粒径大约为4 nm, CdSe-MWCNTs也具有一定的荧光性质.     

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.     

CdS量子点的制备及细胞膜初步荧光标记

以巯基乙酸为稳定剂,通过控制反应温度、反应时间及pH值,在水相中合成了稳定的受激发出紫光、蓝光、绿光、黄光和红光的CdS量子点;通过紫外可见吸收光谱、荧光光谱和X射线衍射谱(XRD)对产物的光学性能和晶体结构进行了表征,结果表明所合成的CdS量子点分散性较好,量子产率为8%,为立方晶型,粒径约1 nm;利用荧光倒置显微镜观察了量子点在洋葱内表皮细胞膜上聚集及受激发射荧光行为,实现细胞膜初步标记.     

Preparation and formaldehyde sensitive properties of N-GQDs/SnO2 nanocomposite

Graphene quantum dots (GQDs) have both the properties of graphene and semiconductor quantum dots, and exhibit stronger quantum confinement effect and boundary effect than graphene. In addition, the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization, which can be dispersed in common solvents and compounded with solid materials. In this work, the SnO₂ nanosheets were prepared by hydrothermal method. As the sensitizer, nitrogen-doped graphene quantum dots (N-GQDs) were prepared and composited with SnO₂ nanosheets. Sensing performance of pristine SnO₂ and N-GQDs/SnO₂ were investigated with HCHO as the target gas. The response (R_a/R_g) of 0.1% N-GQDs/SnO₂ was 256 for 100 ppm HCHO at 60 °C, which was about 2.2 times higher than pristine SnO₂ nanosheet. In addition, the material also had excellent selectivity and low operation temperature. The high sensitivity of N-GQDs/SnO₂ was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs. This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.     

Preparation,characterization and biocompatibility of aspartic acid modified CdTe quantum dots

This study aims at preparing water soluble aspartic acid （ASP） modified CdTe quantum dots with tunable fluorescence emission controlled by reaction time. The size of the synthesized CdTe quantum dots was evaluated using transmission electron microscope （TEM） and also calculated based on their UV-vis spectra. The optical properties of TGA-CdTe quantum dots were characterized by UV-vis and fluorescence （FL） spectroscopy. The red-shift in the UV-vis absorption and FL emission with the increase of reaction time was observed. The biocompatibility examination indicated that the ASP modified CdTe QDs had low cytotoxicity.