纳米材料作为载体在检测信号放大中的应用进展

纳米材料具有比表面积大、负载量大、易与生物标志物结合等优点,在生物样本检测、蛋白质富集、混合物分离,尤其是检测信号放大方面得到广泛应用。简要综述了纳米金、石墨烯、碳纳米管、碳纳米球、介孔材料在检测信号放大方面的应用,并对其未来的发展方向和前景进行了展望。     

糖纳米材料的研究进展

纳米材料在电子学、光学、磁学和生物医药等方面有着广泛的应用。在过去的20年,金属纳米微粒已经成功地与多肽、蛋白质和DNA结合,但糖类物质直到2001年才被引入到纳米科学中。糖纳米微粒能够很好地构建类似细胞表面糖类表达的生物细胞模型,成为糖生物学、生物药学、材料科学中十分出色的研究工具。随着研究的深入,糖纳米材料由于其制备简便,具有独特的物理、化学和生物性质,其在生物医学成像、诊断及治疗等方面有着广泛的应用前景。     

纳米磁性液体的性质、制备方法及其在生物医药中的应用进展

纳米磁性液体是一种新型的功能材料,其在蛋白质、核酸分离纯化、微生物检测、基因治疗等方面有着广泛的应用前景。磁性纳米材料现已广泛应用于我们生产生活中的各个领域,其应用可谓包罗万象,它在旋转轴动态密封、扬声器制作、阻尼器件制造、选矿分离、治疗癌症、精密研磨和抛光等方面具有极大的价值。本文对纳米磁性液体的性质和制备进行了简介,并详细介绍了其功能及其在蛋白质、核酸分离纯化和在细胞分离、微生物检测、基因治疗方面的应用。并对其发展前景进行了展望。     

纳米材料在生物医学检测中的应用

纳米技术的兴起,对生物医学领域的变革产生了深远的影响。纳米材料是纳米技术发展的重要基础,它具有许多传统材料所不具备的独特的理化性质,因此在生物医学、传感器等重要技术领域有着广泛的应用前景。对几类常见的纳米材料包括纳米金、量子点、磁性纳米粒子、碳纳米管和硅纳米线在蛋白质、DNA、金属离子以及生物相关分子检测方面的应用进行综述。     

纳米水解酶的研究进展

水解酶由至少200种单独的蛋白质组成,可催化一系列独特化学键的水解.但是天然酶的固有缺点,如易变性、成本高、制备费力和回收困难,极大地限制了它们的实际应用.为了克服这些缺点,研究人员长期以来致力于探索人工水解酶模拟物.自从2007年发现Fe₃O₄纳米颗粒可以作为过氧化物酶模拟物,关于纳米酶的研究不断涌现.与天然酶相比,纳米酶具有制备简单、可大规模生产、环境耐受性强、制备及储存成本低廉、可重复使用等优势.纳米水解酶是指具有水解酶活性的纳米材料,金属有机框架材料、碳基纳米材料和金纳米粒子等的水解酶活性均已被报道.近年来,纳米水解酶研究领域进入蓬勃发展期,然而至今尚未见关于纳米水解酶的综述.本文首先根据水解底物的不同对纳米水解酶进行分类并分别讨论其催化机理,之后对影响纳米水解酶活性的因素及纳米水解酶的应用进行总结,最后概述和讨论纳米水解酶的当前挑战和未来前景.     

纳米氧化铈作用下活性污泥胞外聚合物及溶解性微生物产物特性

【目的】纳米氧化铈作为一种应用普遍的人工纳米材料,其生物毒性和环境效应得到了越来越多的重视。尝试从微生物代谢产物的角度,解读纳米氧化铈对活性污泥微生物的影响规律和过程。【方法】在实验室活性污泥系统中投加不同质量浓度纳米氧化铈,研究纳米氧化铈短期作用下微生物胞外聚合物(EPS)和溶解性微生物产物(SMP)这两类主要的微生物代谢产物含量和组分的变化规律。【结果】短期作用下,EPS和SMP的总量都随着纳米氧化铈浓度的增加而增加。低浓度纳米CeO_2不会导致活性污泥中松散型胞外聚合物(LB-EPS)、紧密型胞外聚合物(TB-EPS)含量和组分的显著改变。高浓度纳米CeO_2(25 mg/L以上)作用下TB-EPS含量和组分不受影响,而LB-EPS中多糖和蛋白质为抵抗纳米CeO_2毒性而增多。EPS分层组分含量显著提高,且LB-EPS的增幅显著高于TB-EPS增幅。当纳米氧化铈浓度为50 mg/L时,相较于空白对照组,蛋白质和多糖增幅分别达到35.18%和46.57%。当纳米氧化铈超过25 mg/L以上时,SMP不仅出现蛋白质,多糖和腐殖酸的含量也明显增加。【结论】SMP中蛋白质的产生,可能会与纳米材料相结合,以减小纳米材料的毒性。当纳米氧化铈浓度较低时,EPS的吸附作用会抵制其进入细胞内,当纳米氧化铈浓度较高时,刺激细胞产生更多EPS吸附纳米CeO_2,形成更厚的外部屏障层保护细胞。EPS和SMP的共同作用,构成了微生物细胞对纳米CeO_2的毒性抵抗机制。     

纳米材料生物效应研究进展

随着纳米技术的快速发展,纳米材料在医学成像、疾病诊断、药物传输、癌症治疗、基因治疗等领域的应用和基础研究也在飞速发展.同时,纳米材料的这些有益应用使得人体通过吸入、经口、皮肤吸收和静脉注射等不同方式受到暴露.当纳米材料与生物体系发生相互作用时,有可能产生负面生物学效应,而这些潜在的毒理效应都是未知的.综述了纳米材料在生物医学领域巨大的应用前景,关注其对心血管系统、呼吸系统及转运到其他器官可能造成的负面效应,并探讨了纳米颗粒在引起心血管疾病及肺部炎症方面的可能机理与作用途径.最后对纳米材料的安全性评估和研究重点进行了总结.     

内质网在纳米材料毒性效应形成中的作用及机制

随着纳米材料在食品、药物、生物医学等多领域的应用,其在生产使用过程中对人类健康的影响引起了广泛关注.内质网是蛋白质折叠与加工修饰、脂质合成以及Ca~(2+)储存的主要场所,是维护细胞内稳态的重要细胞器.内质网作为纳米材料的主要靶细胞器之一,在纳米材料引起的毒性效应中起重要作用.本文结合近年来国内外相关研究进展,阐述了纳米银(Ag-NPs)、纳米金(Au-NPs)、纳米二氧化钛(TiO_2-NPs)、纳米氧化锌(ZnO-NPs)、纳米二氧化硅(SiO_2-NPs)、富勒烯(C_(60))、单壁与多壁碳纳米管(SWCNTs/MWCNTs)以及石墨烯与氧化石墨烯(GO)等典型纳米材料对内质网结构与功能的影响,并归纳总结了内质网在不同纳米材料诱导的毒性效应中的作用及其异同点.纳米材料可通过引起内质网应激诱导细胞凋亡、炎症反应以及细胞自噬,还可通过激活IP_3信号通路诱导内质网Ca~(2+)释放激活钙依赖的细胞凋亡.纳米材料可在内质网中积累造成结构损伤及功能障碍,还可诱导内质网自噬.     

磁性纳米材料的生物医学应用进展

以四氧化三铁为代表的医用磁性纳米材料具有独特的磁学性能、表面易功能化、良好的生物学相容性等特点,在纳米医学相关领域展现出巨大的应用前景,特别是近年来它作为可介导外场的智能材料,在材料设计和生物医学应用方面均取得了突破性的进展.鉴于此,本文围绕磁性氧化铁纳米材料的生物医学应用,着重介绍近年来其在磁共振影像探针、磁热和磁力效应的生物医学应用、诊疗一体化以及纳米酶催化等领域的研究进展,并对磁性纳米材料在生物医学领域未来的发展方向进行了展望.     

介孔碳纳米材料的制备及其在药物传递方面的应用进展

新型功能性纳米材料在设计和制备技术方面的进步为纳米医学的发展提供了很大的机遇。在过去十年中,介孔碳纳米材料在制备和应用方面获得了巨大的进步。作为一种新型无机材料体系,介孔碳纳米材料结合了介孔的结构以及碳质组成的特点,显示出不同于传统介孔二氧化硅以及其它一些碳基材料体系(碳纳米管、石墨烯、富勒烯等)的优越特性。介孔碳纳米材料在药物的吸附与控释、光热治疗、协同治疗、肿瘤细胞的荧光标记、催化、生物传感、生物大分子的分离等诸多领域表现出其他多孔材料难以达到的优越性和应用潜力。本文对介孔碳纳米材料的制备和修饰技术进行介绍,重点关注介孔碳纳米颗粒在药物负载和光热控释方面的应用,最后对介孔碳纳米材料在生物医学领域的应用前景和所面临的关键问题进行讨论。     

Assembly of single-walled carbon nanohorn supported liposome particles

Nanoparticle-supported liposomes can be a promising platform for drug delivery, vaccine development, and biomedical imaging. Single-walled carbon nanohorns are a relatively new carbon nanomaterial, and they could be used as carriers of drug and imaging reagents. Assembling lipids around carbon nanohorns would confer this nanomaterial much broader applications such as vaccine development and targeted drug delivery by embedding a target protein or immunogenic protein into the lipid bilayer structure. Here, we show the assembly of functionalized single-walled carbon nanohorns (-CH(2)-CH(2)-COOH(x), ~100 nm) with positively charged lipids through a freeze and thaw cycle. The assembled complex particles can be readily separated from individual nanohorns or liposomes under specific centrifugation conditions. The results from transmission electronic microscopy, flow cytometry through nitrobenzoxadiazole labeled lipids, and zeta potential analysis clearly show that the nanohorns are encapsulated by liposomes with a median size of ca. 120 nm.     

One‐pot synthesis of carbon dots using two different acids and their respective unique photoluminescence property

Carbon dots, a new class of nanomaterial with unique optical property and have great potential in various applications. This work demonstrated the possibility of tuning the emission wavelength of carbon dots by simply changing the acid type used during synthesis. In particular, sulfuric and phosphoric acids and a mixture of the two were used to carbonize the same starting precursor, sucrose. This resulted in the isolation of carbon dots with blue (440 nm) and green (515 nm) emission. Interestingly, the use of an acid mixture at various ratios did not shift the initial emission profile, but did obviously alter the fluorescence efficiency of the peaks. This clearly showed that acid type can be used as an alternative tool to produce carbon dots that have different emissions using the same starting precursor. Copyright © 2016 John Wiley & Sons, Ltd.     

CARBANA: Carbon analysis program forprotein sequences

There are lots of works gone into proteins to understand the nature of proteins. Hydrophobic interaction is the dominant force that drives the proteins to carry out the biochemical reactions in all living system. Carbon is the only element that contributes towards this hydrophobic interaction. Studies find that globular proteins prefer to have 31.45% of carbon for its stability. Taking this as standard, a carbon analysis program has been developed to study the carbon distribution profile of protein sequences. This carbon analysis program has been made available online. This can be accessed at www.rajasekaran.net.in/tools/carbana.html. This new program is hoped to help in identification and development of active sites, study of protein stability, evolutionary understating of proteins, gene identification, ligand binding site identification, and to solve the long-standing problem of protein-protein and protein-DNA interactions.     

低碳经济计量模式

首先对"低碳经济"进行了讨论,进而提出了"碳循环经济"概念;对现有碳计量进行研究,提出了相应改进计算公式:碳绩效和碳经济密度。最后,对碳责任分担进行了探讨,提出了发达国家和发展中国家"责任共担、区别对待"的碳责任担负的计算模式。     

ENHANCED TRANSPORT OF INORGANIC CARBON INTO ALGAL CELLS AND ITS IMPLICATIONS FOR THE BIOLOGICAL FIXATION OF CARBON1,2

Kinetics of uptake of inorganic carbon by the freshwater green alga Chlamydomonas reinhardtii Dang. suggest that rates of fixation may be enhanced at low tensions of CO₂ by transport of bicarbonate from the cell surface to the chloroplast. Results are evaluated in the context of models that treat diffusion and reaction of dissolved inorganic carbon across a 3 dimensional finite boundary layer, and they are consistent with the claim that CO₂ alone is the substrate used during carbon fixation. An alternative hypothesis, which presumes that both CO₂ and bicarbonate are used as substrates, yields predictions which are inconsistent with the data. Instead, bicarbonate seems to act only as a vehicle for the transport of inorganic carbon into the cell, thereby adding its flux to that of CO₂, and enhancing rates of synthesis that would otherwise be restricted by uptake of CO₂ alone.     

Dynamic recognition and repair of DNA complex damage

Irradiation (IR) can be used to treat cancer by inducing complex and irreparable DNA damage in the cancer cells, which may lead to their apoptotic death. However, little is known about the molecular mechanism of this DNA damage. Here, the non-small-cell lung cancer cell line A549 was treated with either X-ray or carbon ion combined with bleomycin (BLM). The cell survival rate, frequency of double-strand breaks (DSBs), dynamic changes in γH2AX, and p53 binding protein 1 (53BP1), and protein expression of Ku70, Rad51, and XRCC1 were determined by the clone formation assay, agarose gel electrophoresis, immunofluorescence, and western blot analysis. The results showed that the most obvious complex DSBs occurred in the carbon IR + BLM group. The number of γH2AX and 53BP1 foci in the 0.5 hr X-ray IR + BLM group was the highest (p < 0.001) among all the groups. γH2AX foci were detected in the nucleus at 0.5, 1, 2, and 4 hr, but were distributed throughout the cell at 6 hr after IR in the carbon ion IR + BLM group. The expression of Ku70 increased and XRCC1 decreased at 2 and 6 hr after IR. Our data indicate that a DNA damage frequency of 13.4/Mbp is caused by clustered DNA damage and further show a correlation between γH2AX, 53BP1, and XRCC1 levels and the extent of DNA damage. The results of this study provide insights into DNA damage recognition and a rationale for the clinical use of radiotherapy.     

Recent advances in nano-carrier immobilized enzymes and their applications

Enzymes have been widely used because of their catalytic properties, and immobilization is a promising technique to improve their catalytic activity and stability. Due to their large specific surface areas, exceptional chemical, mechanical, thermal and cost effective characteristics, nanomaterials should be ideal carriers for the immobilization of enzymes. Enzymes immobilized on nano-carriers are more robust and stable, and can be recycled and reused. This review focuses on the nanomaterial immobilized enzymes and their applications. The introduction addresses the advantages of immobilized enzymes and the features of enzyme immobilization nanocarriers. The next section covers carbonaceous nanomaterials used in enzymes immobilization, with subsections on carbon nanotube, graphene, graphene oxide and reduced graphene oxide. The third section treats metallic nanomaterials for enzymes immobilization, with subsections on metal (gold), metal oxide (titanium dioxide, zinc oxide) and metal hydroxide (layered double hydroxide) nanomaterials. Then, the next section summarizes the applications of nanomaterial immobilized enzymes. A concluding section discusses the challenges and prospects of nanomaterial immobilized enzymes.     

Carbon debt repayment or carbon sequestration parity? Lessons from a forest bioenergy case study in Ontario,Canada

Forest bioenergy can contribute to climate change mitigation by reducing greenhouse gas (GHG) emissions associated with energy production. We assessed changes in GHG emissions resulting from displacement of coal with wood pellets for the Atikokan Generating Station located in Northwestern Ontario, Canada. Two contrasting biomass sources were considered for continuous wood pellet production: harvest residue from current harvest operations (residue scenario) and fibre from expanded harvest of standing live trees (stemwood scenario). For the stemwood scenario, two metrics were used to assess the effects of displacing coal with forest biomass on GHG emissions: (i) time to carbon sequestration parity, defined as the time from the beginning of harvest to when the combined GHG benefit of displacing coal with biomass and the amount of carbon in regenerating forest equalled the amount of forest carbon without harvest for energy production; and (ii) time to carbon debt repayment, defined as the time from the beginning of harvest to when the combined GHG benefit of displacing coal with biomass and the amount of carbon in the regenerating forest equalled forest carbon at the time of harvest. Only time to carbon sequestration parity was used for the residue scenario. In the residue scenario, carbon sequestration parity was achieved within 1 year. In the stemwood scenario, times to carbon sequestration parity and carbon debt repayment were 91 and 112 years, respectively. Sensitivity analysis showed that estimates were robust when parameter values were varied. Modelling experiments showed that increasing growth rates for regenerating stands in the stemwood scenario could substantially reduce time to carbon sequestration parity. We discuss the use of the two metrics (time to carbon sequestration parity and time to carbon debt repayment) for assessing the effects of forest bioenergy projects on GHG emissions and make recommendations on terminology and methodologies for forest bioenergy studies.     

Effects of climate change on labile and structural carbon in Douglas-fir needles as estimated by δ13C and Carea measurements

Models of photosynthesis, respiration, and export predict that foliar labile carbon (C) should increase with elevated CO₂ but decrease with elevated temperature. Sugars, starch, and protein can be compared between treatments, but these compounds make up only a fraction of the total labile pool. Moreover, it is difficult to assess the turnover of labile carbon between years for evergreen foliage. Here, we combined changes in foliar C_area (C concentration on an areal basis) as needles aged with changes in foliar isotopic composition (δ¹³C) caused by inputs of ¹³C‐depleted CO₂ to estimate labile and structural C in needles of different ages in a four‐year, closed‐chamber mesocosm experiment in which Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were exposed to elevated temperature (ambient + 3.5 °C) and CO₂ (ambient + 179 ppm). Declines in δ ¹³C of needle cohorts as they aged indicated incorporation of newly fixed labile or structural carbon. The δ ¹³C calculations showed that new C was 41 ± 2% and 28 ± 3% of total needle carbon in second‐ and third‐year needles, respectively, with higher proportions of new C in elevated than ambient CO₂ chambers (e.g. 42 ± 2% vs. 37 ± 6%, respectively, for second‐year needles). Relative to ambient CO₂, elevated CO₂ increased labile C in both first‐ and second‐year needles. Relative to ambient temperature, elevated temperature diminished labile C in second‐year needles but not in first‐year needles, perhaps because of differences in sink strength between the two needle age classes. We hypothesize that plant‐soil feedbacks on nitrogen supply contributed to higher photosynthetic rates under elevated temperatures that partly compensated for higher turnover rates of labile C. Strong positive correlations between labile C and sugar concentrations suggested that labile C was primarily determined by carbohydrates. Labile C was negatively correlated with concentrations of cellulose and protein. Elevated temperature increased foliar %C, possibly due to a shift of labile constituents from low %C carbohydrates to relatively high %C protein. Decreased sugar concentrations and increased nitrogen concentrations with elevated temperature were consistent with this explanation. Because foliar constituents that vary in isotopic signature also vary in concentrations with leaf age or environmental conditions, inferences of c_i/c_a values from δ ¹³C of bulk leaf tissue should be done cautiously. Tracing of ¹³C through foliar carbon pools may provide new insight into foliar C constituents and turnover.     

Soil carbon pool and fertility under natural evergreen broadleaved forest and its artificial regeneration forests in southern Sichuan Province, China

The measurement of total soil organic matter (SOM) is not sensitive enough to detect short and medium term changes, and thus meaningful fractions of SOM should be measured. The carbon management index (CMI) was shown to be a useful technique for describing soil fertility. Soil samples were collected from natural evergreen broadleaved forest and its artificial regeneration forests of Sassafras tzumu, Cryptomeria fortunei and Metasequoia glyptostroboides in southern Sichuan Province, China, to determine soil carbon fractions, available nutrients, enzyme activity and CMI. Regression analysis was used to determine the relationship between soil carbon fractions, CMI and fertility. The results showed that the contents of soil organic carbon, water-soluble carbon, microbial biomass carbon, labile carbon, non-labile carbon, hydrolysis-N, available-P and available-K, the activity of invertase, phosphatase and catalase, and CMI were ranked with different seasons and followed the order: natural evergreen broadleaved forest > Sassafras tzumu plantation > Metasequoia glyptostroboides plantation > Cryptomeria fortunei plantation. The soil carbon fractions and CMI were significantly positively (P < 0.05) correlated with available nutrients and enzyme activity. The results indicate that soil carbon fractions and CMI could be used to evaluate the soil fertility for natural evergreen broadleaved forest and its artificial regeneration forests.