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。     

氮掺杂石墨烯量子点的制备及其在细胞成像中的应用

为克服现有量子点制备技术中存在的荧光量子产率较低及生物相容性差的问题,通过一步水热法合成一种高荧光量子产率的氮掺杂石墨烯量子点(N?GQDs),其荧光量子产率为94％.N?GQDs粒径在20～40 nm之间,最大激发波长为390 nm,发射波长为450 nm.N?GQDs呈现亮蓝色荧光,具有良好的光致发光作用.N?GQ...     

掺氮高荧光碳点的一步法制备及对痕量Hg(Ⅱ)离子的选择性检测

采用一步水热法制备了一种水溶性的、具有良好荧光性能的掺氮碳量子点(N-碳点),其尺寸大小均匀,约为7 nm。N-碳点的荧光强度随N的掺杂量、水热反应温度、溶液的pH值而改变。在最佳反应条件下所制备的N-碳点的荧光量子产率高达24.4%。该N-碳点作为一种简单、低成本的荧光探针用于检测痕量Hg²⁺,具有高选择性和高灵敏度的特点,其最低检测极限可达到0.02 μmol·L^-1 (4.012 ng)。     

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。     

CdS纳米晶@碳点复合物膜的电致化学发光

采用热解柠檬酸法制备碳点(CDs),并将之与表面无包裹剂的CdS纳米晶(CdS NCs)超声复合制备CdS纳米晶@碳点(CdS NCs@CDs)复合物。研究了复合物膜阴极电致化学发光(ECL),探讨了CDs对CdS纳米晶膜ECL增强的机理。CDs分散性良好、尺寸在1.5~4 nm之间;与粒径约为4 nm的CdS纳米晶按体积比2∶3复合后,在360 nm光激发下复合物具有最强的荧光发射且表现为CDs的荧光。同时,复合物膜产生归属于激发态CdS纳米晶的最强的ECL发射,且ECL发光峰起置电势正移至-1.05 V。复合物膜的ECL发射是pH依赖的,在pH值为6时,复合物膜具有最大的ECL强度,为CdS纳米晶膜ECL强度的19倍。这种ECL增强源于CDs能束缚大量电子产生局域电场从而促进近邻CdS纳米晶激发态的形成与弛豫。     

以太西煤为碳源合成碳量子点用于铁离子检测的研究

以太西煤为碳源,采用硝酸氧化法辅助水热合成了具有绿色荧光的碳量子点(CDs)。该量子点具有良好的稳定性和水分散性,平均尺寸为3.64 nm。通过透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)、傅立叶红外光谱仪(FTIR)、紫外-可见吸收光谱仪(UV-Vis)、荧光光谱仪等对碳量子点的结构和光学性能进行表征。基于荧光猝灭原理,在最优检测条件下,Fe3+在0.6×10-6~2.5×10-6mol/L及3.0×10-6~21.0×10-6mol/L浓度范围内与CDs的荧光猝灭效率呈良好的线性关系,Fe3+的检出限为6.7×10-7mol/L。     

温敏性碳量子点的快速制备、荧光性质及细胞成像应用

以草酸和尿素为碳源,超纯水为溶剂,采用微波方法快速合成了具有热敏性的氮掺杂碳量子点,对其形貌、结构、荧光性质和荧光强度的影响因素,以及细胞毒性进行了测试和讨论,并用于小鼠结肠癌细胞(CT26.WT)成像。结果表明,制备的碳量子点近似球形,粒径约3.8 nm。碳量子点具有良好的温度响应的荧光性质。在10~80℃温度范围内,相对荧光强度与温度之间存在良好的线性关系。随着温度的增加,碳量子点的荧光强度减小,温度从10℃升至80℃,相对荧光强度减少了25%,当温度反向降低时,其荧光强度恢复到原始值。碳量子点温度与荧光强度之间的线性关系,使之在温度响应的荧光传感领域具有潜在的应用价值。对碳量子点进行氮掺杂能有效提高其荧光量子产率,当草酸和尿素质量比为3∶1时,荧光量子产率最高,为9.5%。另外,合成的碳量子点还具有优异的抗盐性能、强稳定性等特点,不仅能有效被CT26.WT细胞吞噬,还显示出低毒性和生物相容性,MTT分析结果表明,在1 000μg·mL~(-1)的碳量子点存在下,CT26.WT细胞存活率达85%,荧光碳量子点有望作为温敏性的荧光纳米探针在细胞研究领域得到应用。     

氮掺杂石墨烯量子点用于定量分析牛血清白蛋白的含量

合成了氮掺杂石墨烯量子点,并基于茜素红-氮掺杂石墨烯量子点之间的相互作用形成氢键复合物,茜素红可以对所合成的氮掺杂石墨烯量子点产生明显的荧光猝灭作用(荧光关),氮掺杂石墨烯量子点荧光强度的变化(F0/F)与茜素红浓度(2.78~23.59 nmol/L)具有良好的线性关系,检出限为1.24 nmol/L;继续向该溶液中加入牛血清白蛋白,会使原已发生荧光猝灭的氮掺杂石墨烯量子点溶液的荧光发射强度得以恢复(荧光开),且荧光发射强度的恢复与牛血清白蛋白浓度(0.1~0.375 g/L)之间具有良好的线性关系,检出限为0.011 g/L。此外,该"关-开"荧光检测体系被用来定量分析人尿液中的牛血清白蛋白含量,方法已用于实际尿液样品的定量分析。     

氧化石墨烯量子点对鸡卵清蛋白递送-免疫增强佐剂效力评估

利用改进的Hummers法氧化鳞片石墨,获得富含羟基和羧基的氧化石墨烯量子点(GOQDs)。通过透射电子显微镜、X射线衍射、红外光谱及拉曼光谱测试表征其理化性质。此外,利用鸡卵清蛋白(OVA)作为模式抗原,构筑GOQDs/OVA纳米疫苗并评估其载量、安全性、免疫效力等。结果显示,GOQDs/OVA纳米疫苗直径在5nm左右,具有高度的水分散性和稳定性。其对OVA的最大负载量约为 500mg·g^-1,在pH=5.5和7.4环境下24 h的释放率分别为74.65%和56.93%,表现出pH刺激响应释放性能。当GOQDs浓度在500μg·mL^-1以下时,不会引起溶血、细胞损伤、重要组织发生病变等现象。免疫后,与 OVA单独免疫对照组相比,GOQDs/OVA纳米疫苗可以诱导产生高水平的免疫球蛋白G(IgG)、免疫球蛋白G1(IgG1)及免疫球蛋白G2a(IgG2a)抗体,提高白细胞介素(IL)-1β、IL-2、IL-4和IL-6、肿瘤坏死因子-α(TNF-α)和γ干扰素(IFN-γ)的分泌,同时促进脾中辅助性(CD4⁺)和细胞毒性(CD8⁺)T淋巴细胞百分比的增加。     

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。     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Reactions in droplets in microfluidic channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Gemini表面活性剂合成进展

系统总结了近百种Gemini表面活性剂的合成路线和方法,并且按照其结构特点分门别类地进行比较和归纳,对今后Gemini表面活性剂的合成发展方向提出了一些看法,这对促进此类新颖表面活性剂的工业化进程将具有指导意义。     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

乙基香兰素研究前景

报导了近几十年来国内外关于乙基香兰素的研究进展与动态,并简单介绍了本文作者在该方面所取得的研究成果,参考文献33篇。     

Trends in education in analytical chemistry

Summary At the session of the WPAC of Fechem on education in analytical chemistry it was concluded that it is now essential to include chemometrics and basic knowledge of computers in all courses on analytical chemistry.

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Tendenzen in der analytisch-chemischen Ausbildung

Zusammenfassung Bei einer Tagung der WPAC über die Lehre auf dem Gebiet der analytischen Chemie wurde bei der Betrachtung neuer Aspekte festgestellt, daß vor allem Chemometrie und Grundkenntnisse in Computertechnik in die Ausbildung aufgenommen werden sollten.

     

钙与人体及临床

钙是宏量元素，是人体中含量较高的元素之一，体内99％的钙构成骨骼和牙齿以及维持骨骼结构，1％的钙调节人体重要生理功能。钙的含量过高或过低都与许多疾病有关，只有保持一种平衡状态，才能使机体处于正常环境。     

AGET ATRP in the Presence of Air in Miniemulsion and in Bulk

Summary: The recently developed initiation system, activators generated by electron transfer (AGET), is used in atom transfer radical polymerization (ATRP) in the presence of a limited amount of air. Ascorbic acid and tin(II ) 2‐ethylhexanoate are used as reducing agents in miniemulsion and bulk, respectively. An excess of reducing agent consumes the oxygen present in the system and, therefore, provides a deoxygenated environment for ATRP. ATRP of butyl acrylate is successfully carried out in miniemulsion and in the presence of air. During polymerization the radical concentration remains constant. The polymerization reaches over 60% monomer conversion after 6 h, which results in polymers with a predetermined molecular weight = 14 000 g · mol⁻¹ and a low polydispersity ( = 1.23). AGET ATRP of styrene is also successful in bulk in the presence of air, as evidenced by linear semi‐logarithmic kinetics, which leads to polystyrene with an of 13 400 g · mol⁻¹ and a low polydispersity index ( = 1.14).

Appearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).