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1.
范峰华  郑荣波  刘爽  郭雪莲 《生态学报》2021,41(16):6525-6532
近年来,二氧化钛纳米颗粒(TiO2NPs)环境释放量不断增加,并通过多种途径进入湿地生态系统,不可避免地影响到湿地生态系统环境和功能。然而,关于TiO2NPs对沼泽土壤反硝化作用和氧化亚氮(N2O)排放的影响机及制尚不明确。选择典型沼泽土壤,通过室内培养实验研究土壤理化性质、反硝化酶活性、反硝化速率(DNR)和N2O排放对不同剂量TiO2NPs 0 mg/kg (CK)、10 mg/kg (A10)、100 mg/kg (A100)、1000 mg/kg (A1000)输入的响应,探讨TiO2NPs输入对沼泽土壤反硝化作用和N2O排放影响的内在机制。结果表明:不同剂量TiO2NPs处理显著降低了土壤pH (P<0.05),A10处理显著降低土壤总有机碳(TOC)含量(P<0.01),A1000处理显著降低硝态氮(NO3--N)和亚硝态氮(NO2--N)含量(P<0.05)。TiO2NPs处理抑制硝酸盐还原酶(NAR)活性,促进一氧化氮还原酶(NOR)和氧化亚氮还原酶(NOS)活性(P<0.01),A1000处理先促进后抑制了亚硝酸盐还原酶(NIR)活性(P<0.05)。不同剂量TiO2NPs处理抑制了土壤DNR,促进了N2O排放,TiO2NPs处理通过抑制NIR活性,降低土壤DNR,同时通过促进NOR活性,提高N2O排放。综上,TiO2NPs输入通过影响反硝化还原酶活性改变沼泽土壤反硝化过程,导致沼泽土壤N2O排放增加,改变湿地氮的源、汇功能,影响全球气候变化。为TiO2NPs输入的湿地环境风险评估研究提供理论基础。  相似文献   

2.
细胞氧化损伤时8-羟基鸟嘌呤的测定   总被引:3,自引:0,他引:3       下载免费PDF全文
利用H2O2易通过细胞膜而到达核这一特点,初步探讨了不同浓度H2O2对HL-60细胞DNA的氧化损伤程度.发现H2O2浓度在0.4 mmol/L以上时,作用8~24 h可以用气相色谱/火焰离子检测器(GC/FID)检测到氧化损伤标志产物——8-羟基鸟嘌呤(8-oh-G),并观测到在0.4~0.8 mmol/L H2O2作用一定时间时,8-羟基鸟嘌呤含量随H2O2浓度升高而升高.  相似文献   

3.
PKCγ过表达诱导C3H10T1/2细胞生长失控的初探   总被引:1,自引:0,他引:1  
通过DNA重组构建蛋白激酶Cγ(PKCγ)亚类的重组质粒并经基因转染技术和DNA印迹、蛋白质印迹与PKC活性分析,获得了过表达PKCγ的C3H10T1/2细胞——NCP4.NCP4细胞生长速率提高,流式细胞光度术检测表明,NCP4细胞G1期百分率下降,S期和G2+M期百分率升高,与对照组细胞相比,血清依赖性明显下降,贴壁依赖性降低,在软琼脂中形成小集落,出现部分转化表型.进一步检测,首次观察到NCP4细胞中癌基因c-sis表达明显增强,这可能是NCP4细胞血清依赖性下降的分子机理之一.实验表明,在正常C3H10T1/2细胞中PKCγ的过表达可直接导致细胞增殖加速并可诱导出现部分转化特征.  相似文献   

4.
C60对体外培养癌细胞的光致作用研究   总被引:3,自引:0,他引:3  
研究结果表明用C60-磷脂酰胆碱与体外培养的HeLa细胞融合后,以4 000 lx光强度激发C60(C60浓度20 mg/L)对HeLa细胞具有显著的光致杀伤作用.生化测定证实光激发C60导致膜蛋白巯基含量减少、膜脂过氧化、丙二醛含量增高,SDS-PAGE证明膜蛋白交联,荧光偏振显示膜流动性降低,电镜超微膜结构破坏,经MTT法检测,大部分细胞死亡.C60的强烈光致作用证实了Arbogast等认为光激发C60可产生单线态氧的观态.  相似文献   

5.
过氧化氢对培养心肌细胞损伤作用的研究   总被引:13,自引:1,他引:12  
氧化应激时产生大量的自由基,造成心肌细胞的损伤.过氧化氢(H2O2)是有机体氧化代谢产物,同时是一种活性氧.应用不同浓度的H2O2,分别于不同作用时间,动态观察其对心肌细胞的损伤作用.从实验结果看到,低浓度的H2O2(<0.1 mmol/L)作用2 h,使心肌细胞产生早期的生物化学的改变,如MDA产生堆积和细胞周期时相改变(G1期细胞增加,G2期细胞减少),此时心肌酶基本无泄漏,心肌细胞的死亡率很低,HE形态学观察基本无改变;随着H2O2浓度的增加(1~5 mmol/L)和作用时间的延长,进一步诱导细胞损伤加剧,LDH释放和MDA积累明显升高,细胞死亡率也明显增加,已具有统计学意义.同时可观察到其病理形态学的坏死性改变;当10 mmol/L H2O2作用时,细胞大量死亡,形态学可见细胞极度收缩、脱落,形成大面积的细胞脱失区.因此,H2O2作为一种活性氧自由基,依其浓度和作用时间不同可造成不同程度的心肌细胞的损伤.辣根过氧化物酶作为一种自由基清除剂,可明显减少H2O2活性氧自由基对心肌细胞的损伤作用.  相似文献   

6.
蒙书红  常蕾  柳峰松  徐平  张瑶 《微生物学报》2022,62(10):3768-3783
【目的】本研究以分枝菌酸小杆菌(Mycolicibacterium smegmatis)为研究对象,探索适于原核微生物理想的磷酸化富集方法。【方法】我们比较了二氧化钛(TiO2)、Fe3+-NTA和Ti4+螯合在磷酸酯修饰的固相微球(Ti4+-IMAC) 3种不同富集方法磷酸化肽段的富集效率,并用不同分辨率的质谱仪评估富集稳定性。【结果】Ti4+-IMAC富集效率最高,磷酸化位点数是TiO2或Fe3+-NTA方法的7倍以上;TiO2和Fe3+-NTA方法富集到的磷酸化位点数相差不大,与已报道的用TiO2方法富集的磷酸化位点数目接近。Ti4+-IMAC富集结果稳定性很好,高分辨率Lumos质谱仪鉴定到的磷酸化位点数是Velos的2.6倍。【结论】本研究较高效地实现了分枝菌酸小杆菌磷酸化事件的鉴定,共鉴定到2 280个磷酸化蛋白、10 880个磷酸化肽段及4 433个可信磷酸化位点,有望用于其他微生物的磷酸化蛋白质组学研究。  相似文献   

7.
为了弄清血红蛋白A2现象的发生机制,我们对“红细胞HbA2”的化学组成进行了分析。“红细胞HbA2”的双向电泳结果表明,它含有两种血红蛋白成分:一种相当于HbA,另一种很可能是溶血液HbA2。其单向二次电泳结果也证明,它是由溶血液HbA2和HbA所组成。结果初步说明,盘红细胞中HbA2可能与HbA结合存在。两者可能有相互作用,也许这是产生血红蛋白A2现象的原因。  相似文献   

8.
尖吻蝮蛇毒碱性磷脂酶A2的表达及其生化特征   总被引:4,自引:0,他引:4  
将尖吻蝮蛇毒碱性磷脂酶A2A.aBPLA2)基因克隆至温敏表达载体pBLMVL2,在大肠杆菌RR1中成功诱导表达.表达产物A.aBPLA2约占细菌蛋白质总量的20%,并以包涵体的形式存在.纯化包涵体后,将产物变性、复性,然后用FPLC SuperoseTM12纯化,产物经过SDS-聚丙烯酰胺凝胶电泳检测只有单一条带.对纯化后的表达A.aBPLA2进行了酶活性、抑制血小板聚集活性和溶血活性的测定.结果显示,表达A.aBPLA2的酶活性与变性后复性江浙蝮蛇酸性磷脂酶A2酶活性相近,具有类似变性后复性江浙蝮蛇碱性磷脂酶A2的溶血活性,没有抑制血小板聚集活性.最后对磷脂酶A2的结构与这些活性的关系进行了讨论.  相似文献   

9.
Smac/DIABLO在过氧化氢所致C2C12肌原细胞凋亡中的作用   总被引:4,自引:0,他引:4  
为探讨Smac/DIABLO在过氧化氢(H2O2)所致C2C12肌原细胞凋亡中的作用,采用Hoechst 33258染色,观察H2O2 (0.5 mmol/L)处理C2C12肌原细胞不同时间后,细胞核形态学改变并计算凋亡核百分率,DNA抽提及琼脂糖电泳观察凋亡特征性梯状带,利用细胞成分分离后蛋白质印迹分析H2O2是否导致Smac/DIABLO从线粒体释放,采用Caspase检测试剂盒及蛋白质印迹分析Caspase-3和Caspase-9的活化,转染Smac/DIABLO基因,观察Smac/DIABLO过表达对H2O2所致的C2C12肌原细胞凋亡的影响.结果表明:H2O2处理1 h后,Smac/DIABLO从C2C12肌原细胞线粒体释放入胞浆,2 h更明显;H2O2处理4 h后,Caspase-3和Caspase-9活化,12 h达高峰;H2O2处理24 h后,C2C12肌原细胞显示特征性的凋亡形态改变,凋亡核百分率明显升高,DNA电泳出现明显“梯状”条带.与单纯过氧化氢损伤组相比,Smac/DIABLO高表达的C2C12肌原细胞经过氧化氢损伤组的Caspase-3和Caspase-9的活化、凋亡核百分率的升高、“梯状”条带的出现均更明显.结果表明,H2O2可导致Smac/DIABLO从C2C12肌原细胞线粒体释放,促进Caspase-9和Caspase-3的活化而促进细胞凋亡的发生.  相似文献   

10.
为了阐明纳米二氧化钛颗粒(TiO2NPs)对生菜(Lactuca sativa)生长的影响,采用自行设计的水培装置探究不同浓度TiO2NPs (300~1 200 mg/L)下,生菜生长和生理生化指标的变化。结果表明,300 mg/L TiO2NPs能促进生菜幼苗的根长、茎长、叶表面积、鲜重和干重;随着TiO2 NPs浓度增大,生菜的生长指标呈现下降趋势,但仍优于对照组。生菜体内的抗氧化酶(SOD、POD)在低TiO2 NPs浓度(300 mg/L)时,活性明显下降;随着TiO2 NPs浓度增大,这两种抗氧化酶活性逐渐增强。因此,生菜对TiO2NPs胁迫具有浓度依赖性,表现为“低促高抑”,且能够通过抗氧化酶系统来减轻TiO2NPs伤害。  相似文献   

11.

Background

Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2–Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized.

Methods

Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet–visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated.

Results

The apparent quantum efficiency for visible light illuminated TiO2–Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2–Pt successfully ameliorated the subcutaneous infection in mice.

Conclusions

This is the first demonstration of in vivo antibacterial use of TiO2–Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2–Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo.

General significance

These findings suggest that the TiO2–Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings.  相似文献   

12.
A novel TiO2/CdS nanocomposite was prepared and used to fabricate an electrochemiluminescence (ECL) biosensor for the detection of cancer cells for the first time. The nanocomposite exhibited a strong cathodic ECL signal. Folic acid for targeting cell membranes was bound to a TiO2/CdS/3-aminopropyltriethoxysilane film, and specific recognition of folic acid to targeting cells was achieved, leading to a significant decrease in ECL intensity. The decrease in ECL signal was logarithmically related to the cell concentration in the range of 150–9600 cells mL-1. The ECL biosensor could provide a sensitive, selective, and convenient approach for early and accurate detection of cancer cells.  相似文献   

13.
Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO2 was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which TiO2 exerts its toxicity has not been completely understood. In this report, we investigated the mechanisms of nano-anatase TiO2 (5 nm) on LDH activity in vitro. Our results showed that LDH activity was greatly increased by low concentration of nano-anatase TiO2, while it was decreased by high concentration of nano-anatase TiO2. The spectroscopic assays revealed that the nano-anatase TiO2 particles were directly bound to LDH with mole ratio of [nano-anatase TiO2] to [LDH] was 0.12, indicating that each Ti atom was coordinated with five oxygen/nitrogen atoms and a sulfur atoms of amino acid residues with the Ti–O(N) and Ti–S bond lengths of 1.79 and 2.41 Å. We postulated that the bound nano-anatase TiO2 altered the secondary structure of LDH, created a new metal ion-active site for LDH, and thereby enhanced LDH activity.  相似文献   

14.
The crystal-face dependence of the dye-sensitized photocurrents and the adsorption properties of benzothiazole merocyanine (Mc[18,1]) dye molecules were investigated, using atomically flat (1 0 0) and (1 1 0) TiO2 single crystal surfaces. From the estimation of the amount of the transferred charge from the TiO2 surface to CO groups of dye molecules based on NEXAFS data, it was revealed that the interaction of the adsorbed molecules and the (1 1 0) surface was much stronger than that for the (1 0 0) surface. On the other hand, the absorbed photon to current conversion efficiency (APCE) value was almost the same for both surfaces. We suggested a possible explanation as follows: the energy difference between the LUMO of Mc[18,1] and the conduction band of TiO2 was large enough to give a nearly 100% quantum efficiency of electron transfer from photoexcited dye to TiO2, which made the difference in the interaction between dye molecules and TiO2 not apparent. The incident photon to current conversion efficiency (IPCE) for the (1 0 0) surface was much larger than that for the (1 1 0) surface, which was explained by the fact that the amount of the adsorbed dye molecules on the (1 0 0) surface was larger than on the (1 1 0) surface, probably due to the larger surface density of five-coordinated Ti sites in the former surface.  相似文献   

15.
The improvement of spinach growth is proved to relate to N2 fixation by nano-anatase TiO2 in this study. The results show that all spinach leaves kept green by nano-anatase TiO2 treatment and all old leaves of control turned yellow white under culture with N-deficient solution. And the fresh weight, dry weight, and contents of total nitrogen, , chlorophyll, and protein of spinach by nano-anatase TiO2 treatment presented obvious enhancement compared with control. Whereas the improvements of yield of spinach were not as good as nano-anatase TiO2 treatment under N-deficient condition, confirming that nano-anatase TiO2 on exposure to sunlight could chemisorb N2 directly or reduce N2 to NH3 in the spinach leaves, transforming into organic nitrogen and improving the growth of spinach. Bulk TiO2 effect, however, was not as significant as nano-anatase TiO2. A possible metabolism of the function of nano-anatase TiO2 reducing N2 to NH3 was discussed.  相似文献   

16.
The direct immobilization of glucose oxidase (GOD) on TiO2/SiO2 nanocomposite and its application as glucose biosensor were investigated. The room-temperature phosphorescence of TiO2/SiO2 nanocomposite can be quenched by hydrogen peroxide (H2O2). The detection of glucose may be accomplished by monitoring the formation of hydrogen peroxide which generated in the oxidation process of glucose with the catalysis of GOD. To our surprise, by using a 96-hole polyporous plate accessory of fluorescence spectrophotometer, the biosensor exhibits excellent linear response to glucose concentrations ranging from 1.0 × 10−9 to 1.0 × 10−2 M with a detection limit of 1.2 × 10−10 M. The TiO2/SiO2 nanocomposite can be used as both supporting material and signal transducer. The phosphorescence intensity and color of the biosensor change obviously and even could be observed with naked eyes by continuous addition of glucose. Based on the room-temperature phosphorescence of TiO2/SiO2 nanocomposite, a new method of solid substrate-room-temperature phosphorimetry (SS-RTP) for glucose determination is proposed. A glucose biosensor was fabricated with wide determination concentration range, low detection limit, high sensitivity, and fast response time. And the biosensor has been successfully applied to the determination of glucose in human blood serum. The coacervation of GOD enzyme and its interaction with TiO2/SiO2 nanocomposite enlarge the surface area and enhance the chemical stability of GOD. The nice biocompatibility, large surface area, good chemical stability and nontoxicity of the TiO2/SiO2 nanocomposite have made this material suitable for functioning as biosensor.  相似文献   

17.
Colloidal silver has been known to have unique antimicrobial activity that may be useful in the construction of antibacterial materials (self-cleaning materials) to aid in the fight against bacteria-related infections. In this study, silver-coated TiO2 (Ag/TiO2) particles prepared through the photo-reduction of Ag+ were investigated as an antibacterial agent against Escherichia coli and Staphylococcus aureus. The deposition of Ag onto the surface was confirmed with SEM and EDS analysis of the post-reaction particles. It was also determined that the initial concentration of Ag+ in solution played a significant role in the effective size of the post-irradiation particles. The antibacterial effectiveness of the Ag/TiO2 was evaluated through the determination of the minimum inhibitory concentration (MIC) of AgTiO2 for each species of bacteria. The MIC values for the Ag/TiO2, on both E. coli and S. aureus, were much lower than the MIC values for Ag metal, and quite comparable to the MIC values for AgNO3. A disc diffusion/antibiotic sensitivity test was also performed using the Ag/TiO2 particles and the results compared with the results obtained for Ag metal, AgNO3 and common antibacterial agents; tetracycline, chloramphenicol, erythromycin, and neomycin. The zone of inhibition diameters for the Ag/TiO2 particles were found to be comparable with those of the other antimicrobial agents.  相似文献   

18.
Minerals such as titanium dioxide, TiO2, and zinc oxide, ZnO, are well known active semiconductor photocatalysts used extensively in heterogeneous photocatalysis to destroy environmental pollutants that are organic in nature. They are also extensively used in sunscreen lotions as active broadband sunscreens that screen both UVB (290-320 nm) and UVA (320-400 nm) sunlight radiation and as high SPF makers. When so photoactivated by UV light, however, these two particular metal oxides are known to generate highly oxidizing radicals (OH and ) and other reactive oxygen species (ROS) such as H2O2 and singlet oxygen, 1O2, which are known to be cytotoxic and/or genotoxic. Hydroxyl (OH) radicals photogenerated from photoactive TiO2 specimens extracted from commercial sunscreen lotions [R. Dunford, A. Salinaro, L. Cai, N. Serpone, S. Horikoshi, H. Hidaka, J. Knowland, FEBS Lett. 418 (1997) 87] induce damage to DNA plasmids in vitro and to whole human skin cells in cultures. Accordingly, the titanium dioxide particle surface was modified to produce TiO2 specimens of considerably reduced photoactivity. Deactivation of TiO2 diminishes considerably, in some cases completely suppresses damage caused to DNA plasmids, to human cells, and to yeast cells compared to non-modified specimens exposed to UVB/UVA simulated solar radiation. The photostabilities of sunscreen organic active agents in neat polar and apolar solvents and in actual commercial formulations have been examined [N. Serpone, A. Salinaro, A.V. Emeline, S. Horikoshi, H. Hidaka, J. Zhao, Photochem. Photobiol. Sci. 1 (2002) 970]. With rare exceptions, the active ingredients undergo photochemical changes (in some cases form free radicals) and the sunscreen lotions lose considerable Sun protection efficacy only after a relatively short time when exposed to simulated sunlight UVB/UVA radiation, confirming the recent findings by Sayre et al. [R.M. Sayre, J.C. Dowdy, A.J. Gerwig, W.J. Shields, R.V. Lloyd, Photochem. Photobiol. 81 (2005) 452].  相似文献   

19.
In Gratzel’s cell, the electrons injected by the photo-excitation of dye molecules, anchored to a mesoporous TiO2 film, efficiently diffuse to the back contact achieving solar energy conversion at efficiencies exceeding 10%. The mesoporous TiO2 surface constituted of randomly arranged nanocrystallites with a roughness factor of the order 1000 is heavily populated with traps, defects and adsorbed species which act as recombination centers. Nevertheless, the cell functions, mitigating recombination expected to occur via the interaction electrons at the surface. Evidence based mainly on 1/f noise measurements is presented to show that dye bonded to the TiO2 surface passivates recombination centers. Furthermore the suppression of trapping-detrapping events at the surface increases the diffusion coefficient of the electrons through the nanocrystalline matrix facilitating electron transport to the back contact. The Gratzel cell is also unique, none of the high bandgap oxide materials other than TiO2 yield energy conversion and quantum efficiencies as high as that of the cells based on TiO2. 1/f noise measurements also reveal a distinct difference between TiO2 and ZnO mesoporous films suggesting that the films made from the latter material are more intensely populated with surface states that mediate recombination.  相似文献   

20.
A novel and highly effective UV-TiO2 photocatalytic reactor was developed for killing microorganisms, including Escherichia coli. Among tested four types of TiO2-immobilized photocatalytic supporters (glass bead, muscovite bead, alginate bead, and TiO2 thin film coated quartz tube), the muscovite bead had a 99.9% percent bactericidal activity within 5 min along with permanent longevity. Adding air bubbles or H2O2 (<50 mg l–1) to the sample solution significantly enhanced the killing activity in that 100% percent of bacterial cells were killed within 3 min.  相似文献   

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