Janus石墨烯量子点在生物膜中的输运行为：分子动力学模拟

作为纳米载体,石墨烯量子点已广泛应用于生物医药领域,然而对于异质结构的石墨烯量子点细胞膜内化路径研究不足。从空间异质性结构设计出发,构建了一系列不同氧化程度与空间异质分布的Janus石墨烯量子点。基于分子动力学模拟研究了不同结构的Janus石墨烯量子点跨膜输运行为,通过分析跨膜输运过程中的构型变化、分子间作用能量、溶剂可及面积等参数,发现Janus石墨烯量子点跨膜输运行为由亲水-亲油平衡、空间异质分布控制,且呈现外力牵引依赖性变化。本文在分子水平上系统研究了Janus石墨烯量子点与细胞膜相互作用规律,对其结构设计及生物医药应用提供理论指导。     

有机笼跨细胞膜易位行为的分子动力学模拟研究

纳米药物具有靶向和缓释特性，是癌症治疗的重要工具。其中，纳米载体的优化设计是提高抗肿瘤纳米药疗效的关键。有机笼是一种新型的多孔纳米材料，因物理化学性质可调性、模块设计等优势脱颖而出，已广泛应用于纳米生物医药等领域。从动力学及热力学研究出发，构建了一系列不同结构的有机笼及其表面修饰衍生物，研究了该纳米载体的细胞膜输运行为。通过分析有机笼在生物膜输运过程中的动力学及热力学性质发现，有机笼结构形变对生物膜输运起着至关重要的作用；此外，聚乙二醇表面修饰提高了有机笼的靶向识别能力，但使得有机笼更加亲水，进而造成了更高的生物膜输运能垒，阻碍跨膜输运。本文在分子水平上系统地阐述了有机笼与细胞膜相互作用规律，对纳米载体设计和在生物医疗方面的应用提供了理论指导。     

用盐桥支撑双分子层脂膜模拟研究锌离子跨细胞膜输运

采用盐桥支撑技术制备镶嵌胆固醇的双分子层卵磷脂(脑磷脂)膜,对膜配方、双分子层脂膜的稳定性、离子通透性、双层膜中胆固醇对离子通透性的影响等进行了研究,得到了最佳制膜工艺,并利用实验制备的双分子层脂膜模拟研究锌离子跨细胞膜的输运过程,建立了锌离子跨细胞膜的吸附．扩散模型,其计算值与实验值基本吻合。     

石墨烯基异质结光催化复合材料的研究进展

石墨烯具有低成本、高电子迁移率、透光率、比表面积与稳定性的特点,近年来在光催化领域作为助催化剂研究广泛.随着研究人员对石墨烯性质的深入研究,基于不同电子结构设计不同石墨烯基异质光催化复合材料,正成为光催化领域所关注的热点,但各类异质结的设计较不明朗.基于异质结设计理论与石墨烯电子结构,本文主要综述了石墨烯基肖特基异质结...     

Janus树枝分子液晶自组装结构研究进展

综述了Janus树枝分子在液晶自组装结构研究方面的进展,阐述了其在液晶材料、主-客体化学、生物医药等方面的应用,并探讨了Janus树枝自组装纳米技术的应用前景。     

多孔石墨烯薄膜可高效分离氢气

<正>日前研究生陶叶晗等发现多孔石墨烯气体中分离,中国石油大学(华东)理学院PG-ES薄膜可高效将氢气从混合出来。国家"千人计划"特聘专家、复旦大学教授李溪认为,此研究成果有望推动新型气体分离膜工艺的研发和技术革新,在产业化推广中具有潜在应用价值。研究人员发现,bottom-up孔洞石墨烯是一种自生长的孔洞石墨烯,具有较易控制的孔结构。他们采用计算机模拟方法,研究不同孔洞结构及模拟条件下石墨烯对不同气体分子的选择性吸附效果,从微观角度来观察石墨烯与气体分子相互作用的动力学行为,进而探索石墨烯在气体分离方面的应用。这种促进石墨烯气体分离膜材料开发的理论具有     

氧化石墨烯膜的制备方法研究进展

氧化石墨烯(GO)作为一种新型二维材料,在能源、环境、石油化工、生物医药、光电材料、催化等领域有巨大的应用潜能。当氧化石墨烯膜用于分离时,有着与传统膜过程不同的分离机理。氧化石墨烯膜的层间距可以通过制备方法进行调节以实现离子、分子等物质的精确筛分。总结了由氧化石墨烯溶液制备氧化石墨烯膜的主要制备方法,如真空过滤法、旋涂法、浸涂法、静电自组装法等。     

石墨烯量子点修饰柔性硅纳米线阵列用于NO2检测

将化学刻蚀法与金属辅助刻蚀法相结合,制备了形貌统一、分布均匀的高质量柔性硅纳米线阵列结构,用石墨烯量子点对其表面进行修饰,得到了表面稳定且具有强载流子传输能力的柔性石墨烯量子点/硅纳米线核?壳结构阵列,用其制备气敏设备检测NO2. 结果表明,基于该阵列的电阻式气敏设备对NO2的检测灵敏性及可重复性极高,检测浓度极限达20 mg/m3;不同弯曲度的柔性石墨烯量子点/硅纳米线阵列的气敏特性未大幅度降低,弯曲90o时响应电流峰值为未弯曲时的70%.     

石墨烯的合成与应用

论述了石墨烯非凡的物理及电学性质,包括电子输运-零质量的狄拉克-费米子行为,量子霍耳效应,最小量子电导率,量子干涉效应的强烈抑制等;石墨烯的机械和化学制备方法和石墨烯在纳电子器件方面、计算机芯片取代硅、制造最快的碳晶体管、减少噪声方面和潜在的储氢材料领域等方面的应用.     

石墨烯量子点光致发光性能及调控机制研究进展

石墨烯量子点是一类重要的石墨烯衍生物，在量子尺寸效应的作用下，石墨烯量子点显示出与传统石墨烯截然不同的半导体特性。目前，石墨烯量子点以其优异的光致发光特性，高稳定性，低生物毒性，可调制的界面结构，在荧光防伪材料、生物成像、肿瘤诊疗、光/电催化等领域展现出突出的优势。从石墨烯量子点光致发光特性出发，对石墨烯量子点的带隙这一关系到该材料在各应用领域的重要基本物性进行总结，旨在明确当前在石墨烯量子点光致发光机制研究、光致发光性能调制两大领域的研究进展与挑战。     

Minimising non-selective defects in ultrathin reduced graphene oxide membranes with graphene quantum dots for enhanced water and NaCl separation

Reduced graphene oxide (rGO) membranes have been intensively evaluated for desalination and ionic sieving applications,benefiting from their stable and well-confined interlayer channels.However,rGO membranes generally suffer from low permeability due to the high transport resistance resulting from the narrowed two-dimensional (2D) channels.Although high permeability can be realized by reducing membrane thickness,membrane selectivity normally declines because of the formation of non-selective defects,in particular pinholes.In this study,we demonstrate that the non-selective defects in ultrathin rGO membranes can be effectively minimised by a facile posttreatment via surface-deposition of graphene quantum dots (GQDs).The resultant GQDs/rGO membranes obtained a good trade-off between water permeance (14 L·m-2·h-1·MPa-1) and NaCl rejection (91％).This work provides new insights into the design of high quality ultrathin 2D laminar membranes for desalination,molecular/ionic sieving and other separation applications.     

石墨烯量子点的制备及应用

石墨烯量子点(GQDs)作为石墨烯家族的最新一员,除了继承石墨烯的优异性能,还因量子限制效应和边界效应而显现出一系列新的特性,引起了化学、物理、材料和生物等各领域科研工作者的广泛关注。GQDs的制备方法通常分自上而下和自下而上的方法。对其各种制备方法和应用分别进行了介绍,并结合各种应用对GQDs的要求给出了制备方法的建议。指出了GQDs研究中存在的问题及发展方向。     

Luminescent graphene quantum dots fabricated by pulsed laser synthesis

Graphene has been the subject of intense research in recent years due to its unique electrical, optical and mechanical properties. Furthermore, it is expected that quantum dots of graphene would make their way into devices due to their structure and composition which unify graphene and quantum dots properties. Graphene quantum dots (GQDs) are planar nano flakes with a few atomic layers thick and with a higher surface-to-volume ratio than spherical carbon dots (CDs) of the same size. We have developed a pulsed laser synthesis (PLS) method for the synthesis of GQDs that are soluble in water, measure 2–6 nm across, and are about 1–3 layers thick. They show strong intrinsic fluorescence in the visible region. The source of fluorescence can be attributed to various factors, such as: quantum confinement, zigzag edge structure, and surface defects. Confocal microscopy images of bacteria exposed to GQDs show their suitability as biomarkers and nano-probes in high contrast bioimaging.     

Enhancement in the fluorescence of graphene quantum dots by hydrazine hydrate reduction

A simple and effective chemical method was reported to enhance the fluorescence of graphene quantum dots (GQDs). Specifically, water-soluble GQDs, prepared by solvothermal synthesis from graphene oxide, are chemically reduced by hydrazine hydrate to produce reduced GQDs (rGQDs). The results show that the hydrazine hydrate reduction not only decreases the O/C atomic ratio of GQDs, also changes the bonding type of N atoms. Such surface/edge chemical bond change of GQDs results in that as-made rGQDs exhibit more than two times fluorescence intensity as strong as that of the pristine GQDs.     

Effect of modified graphene quantum dots on photocatalytic degradation property

The effective use of solar energy in sewage disposal has been extensively investigated. This work focuses on the photocatalytic property of graphene quantum dots (GQDs) and polymer-modified GQDs under visible light. A hydrothermal synthesis route to GQDs was developed by using citric acid as a carbon precursor. The GQDs were modified with polyethylenimine (PEI) and polyethylene glycol (PEG). The obtained GQDs, GQDs-PEIs, and GQDs-PEGs were characterized and their structural information was determined through Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), photoluminescence spectroscopy, and UV–Vis absorption spectroscopy. Results revealed that the GQDs were uniform in size (2–5 nm) and rich in oxygen-containing groups. The GQDs exhibited a strong blue and excitation-independent photoluminescent behavior under excitation wavelengths of 320–420 nm. The photocatalytic performance of these samples was demonstrated on the basis of methylene blue (MB) degradation. The photocatalytic rates of GQDs, GQDs-PEIs, and GQDs-PEGs decreased successively. The polymer-modified GQDs could qualitatively control the degradation rate of MB. Free radical species were generated to oxidize MB under light irradiation. Thus, photocatalytic organic matter degradation, sustained drug release, and tracking can be combined to implement proper sewage disposal.Prime noveltyThe main object of this work is to find out a novel property of graphene quantum dots (GQDs) as efficient nanomaterials for degradation of organic pollutant dyes under visible light irradiation. And, the GQDs exhibited a strong blue and excitation-independent photoluminescent behavior under excitation wavelengths of 320–420 nm. Moreover, the degradation rate could be qualitatively controlled by using different polymer-modified GQDs. Thus, photocatalytic organic matter degradation, sustained drug release, and tracking can be combined to implement proper sewage disposal. Also, the degradation mechanism is discussed.     

To lose is to gain: Effective synthesis of water-soluble graphene fluoroxide quantum dots by sacrificing certain fluorine atoms from exfoliated fluorinated graphene

Water-soluble and blue luminescent graphene fluoroxide quantum dots (GFOQDs) with tunable fluorine coverage and size were effectively synthesized from exfoliated fluorinated graphene (FG) by sacrificing certain fluorine to improved solubility and reaction activity. Morphology investigation indicates that the obtained GFOQDs possess narrow size distribution and the average size is 2.5–3.5 nm. Chemical composition analysis confirms that besides C–F covalent bonds, C–O bonds in the forms of hydroxyl and carbonyl co-exist on the structure of GFOQDs. Moreover, photoluminescence performance research considering the surface state and size has also been conducted, and as anticipated in carbon-based quantum dots the GFOQDs exhibit excitation wavelength-dependent properties. Additionally, rather different from other graphene quantum dots (GQDs) that are often susceptible to pH without additional surface passivation, the GFOQDs themselves are poised to resist pH effects and display stable luminescence in both acid and alkali conditions. These results indicate that our method not only opens up a new avenue to prepare GQDs decorated with fluorine and oxygen, but also can find practical applications in novel GQDs-based devices that require water solubility while keep chemical stability and resistance against pH.     

UV-assisted production of ferromagnetic graphitic quantum dots from graphite

Graphitic quantum dots (GQDs) are synthesized from natural graphite powder. This process involves a few steps such as oxidation, reduction and filtration to obtain the precursor to prepare GQDs. Finally, a combination of UV irradiation and sonication is used to produce GQDs. These quantum dots are further investigated by various characterization techniques. They exhibit blue luminescence and ferromagnetic behavior. The ferromagnetic nature of the GQDs is discussed and explained. Based on the experimental data obtained and theoretical models available in literature, a possible mechanism for the formation of GQDs is proposed. Their properties, including the production yield can be tuned by simply changing the synthesis parameters.     

Cu2ZnSnS4 nanocrystals and graphene quantum dots for photovoltaics

Semiconductor quantum dots exhibit great potential for applications in next generation high efficiency, low cost solar cells because of their unique optoelectronic properties. Cu(2)ZnSnS(4) (CZTS) nanocrystals and graphene quantum dots (GQDs) have recently received much attention as building blocks for use in solar energy conversion due to their outstanding properties and advantageous characteristics, including high optical absorptivity, tunable bandgap, and earth abundant chemical composition. In this Feature Article, recent advances in the synthesis and utilization of CZTS nanocrystals and colloidal GQDs for photovoltaics are highlighted, followed by an outlook on the future research efforts in these areas.     

Graphene quantum dots prepared from chemical exfoliation of multiwall carbon nanotubes: An efficient photocatalyst promoter

We report here a facile preparation of graphene quantum dots (GQDs) by chemical exfoliation of multiwall carbon nanotubes (MWCNTs) using a modified hummers' method. The resultant GQD samples possess strong electronic property, revealing great potential for photocatalyst design. As an efficient promoter, GQDs/P25 nanocomposites have been successfully prepared by simple wet impregnation and subsequent thermal annealing at 200 °C. In the tests of photocatalytic degradation of organic dyes under visible-light irradiation, the GQDs promoted P25 samples which shows much higher photocatalytic activity compared to the pure P25, indicating the crucial roles of GQDs.