Carbon Nanotube as Ultrasensitive Biosensor for DNA Detection:A First-Principles Calculation

We perform first-principles calculation to study the transport properties of the acid dopped on C（4,4） carbon nanotube coupled to two C （4,4） carbon nanotube electrodes using the non-equilibrium Green formalism combined with the density-func- tional theory. In particular, we just consider the acid of glycine and alanine molecule dopped on 8 layers C（4,4） carbon nanotube sandwiched between two C（4,4） carbon nan- otube electrodes. It is found that the equilibrium conductance of the pure C（4,4） carbon nanotube at Fermi energy is close to 2 GO, two eigenchannels which contribute to the e- quilibrium conductance are fully open. Both of the two types dopping reduce the con- ductivity of the carbon nanotube. Compared with the alanine molecule, the alanine in- fluence the transport properties of the C（4,4） carbon nanotube much more greatly. At non-equilibrium, with the increase of the applied bias voltage, more visible current dif- ferences appear between the glycine and alanine molecule, which may have the potential use to distuguish the acid of glycine and alanine molecules. A detailed analysis of the transmission coefficient of the eigenchannels, the projected density of states are made to reveal the mechanism of the differences.     

阳极氧化法制备的二氧化钛纳米管在钛表面改性中的研究进展

采用阳极氧化法在钛基体表面原位制备高度有序的二氧化钛(TiO2)纳米管阵列,探讨阳极氧化电压、次数、电解液种类、电解液浓度和电解液温度等对二氧化钛纳米管表面形貌的影响.相对于微米级表面,TiO2纳米管具有更好的促进体外矿化和促进成骨性,同时可作为生物载体负载生长因子和抗生素等载体.本文就此作一综述.     

人脐带间充质干细胞通过线粒体转移减轻肝细胞缺血-再灌注损伤的机制研究

目的  探讨人脐带间充质干细胞（HUC-MSC）通过线粒体转移减轻肝细胞缺血-再灌注损伤（IRI）的作用机制。方法  将正常人肝细胞株L02分为空白对照组、氧糖剥夺（OGD）组、实验对照组、L02与HUC-MSC共培养组（L02+HUC-MSC组）,其中L02+HUC-MSC组根据L02与HUC-MSC不同共培养比例分为10:1共培养组（A组）、4:1共培养组（B组）、2:1共培养组（C组）、1:1共培养组（D组）和1:2共培养组（E组）。采用流式细胞术检测L02细胞凋亡率和细胞内活性氧簇（ROS）相对量;采用流式细胞术检测L02的MitoTracker阳性率;采用激光共聚焦显微镜观察HUC-MSC向L02转移线粒体的情况。结果  OGD组L02细胞凋亡率和细胞内ROS相对量高于空白对照组（均为P < 0.05）;与OGD组比较,B、C、D、E组L02细胞凋亡率均降低（均为P < 0.05）,E组L02细胞内ROS相对量降低（P < 0.05）。A组L02的MitoTracker阳性率与实验对照组比较,差异无统计学意义（P>0.05）,B、C、D、E组均较实验对照组增加（均为P < 0.05）,并呈浓度依赖性。在激光共聚焦显微镜下可观察到线粒体通过隧道纳米管（TNT）从HUC-MSC向L02转移。结论  HUC-MSC可通过细胞间直接转移线粒体的方式减轻肝细胞IRI后细胞凋亡和降低细胞内ROS水平。     

多壁碳纳米管对神经生长因子诱导的PC12细胞分化的影响

目的:观察多壁碳纳米管(MWCNTs)对神经生长因子诱导的PC12细胞分化的影响。方法:PC12细胞,随机分为对照组、神经生长因子(NGF)组和NGF+MWCNTs组(n=5),对照组予空白处理,其它2组加入NGF,NGF+MWCNTs组还加入MWCNTs,运用试剂盒CCK-8分别检测5、10、30、60μg/mL MWCNTs孵育48 h后的细胞活性;通过染色观察MWCNTs孵育细胞48 h的细胞状态,免疫荧光检测F-肌动蛋白、β-tubulinⅢ的构象变化。结果:MWCNTs浓度>30μg/mL时有细胞毒性;30μg/mL的MWCNTs孵育细胞48 h,MWCNTs导致F-肌动蛋白、β-tubulinⅢ在细胞边缘表达减弱或凝结成结节样。结论:MWCNTs浓度>30μg/mL,孵育48 h,对细胞有毒性作用,MWCNTs以团状或折叠状存在于细胞内,致细胞凋亡。     

Imogolite Reinforced Nanocomposites: Multifaceted Green Materials

This paper presents an overview on recent developments of imogolite reinforced nanocomposites, including fundamental structure, synthesis/purification of imogolite, physicochemical properties of nanocomposites and potential applications in industry. The naturally derived nanotubular material of imogolite represents a distinctive class of nanofiller for industrially significant polymer. The incompatibility between the surface properties of inorganic nanofiller and organic matrix has prompted the need to surface modify the imogolite. Early problems in increasing the binding properties of surface modifier to imogolite have been overcome by using a phosphonic acid group. Different approaches have been used to gain better control over the dispersal of nanofiller and to further improve the physicochemical properties of nanocomposites. Among these, polymer grafting, in situ synthesis of imogolite in polymer matrix, and spin-assembly are some of the promising methods that will be described herein. This imogolite reinforced nanocomposite of enhanced optical and mechanical properties, and with unique biological and electronic properties, is expected to become an important category of hybrid material that shows potential for industrial applications.     

二氧化钛纳米管抗菌性能在口腔种植领域的研究进展

钛(Ti)及其合金已被广泛应用于口腔种植领域.但由于纯钛表面是生物惰性的,细菌易粘附于其表面并形成生物膜,这是导致种植体植入术后感染的主要原因.通过阳极氧化法可在钛表面制备出紧密排列的纳米管状结构,形成的二氧化钛纳米管(TiO2纳米管)具有高比表面积、高亲水性的特点.TiO2纳米管表面可促进成骨细胞粘附增殖并有效减少细...     

Multi-walled carbon nanotubes injure the plasma membrane of macrophages

Carbon nanotubes (CNTs) are emerging nanotechnology materials which are likely to be mass-produced in the near future. However, prior to mass-production, certain health-related concerns should first be addressed. For example, when inhaled, the thin-fibrous shape and the biopersistent characteristics of CNTs may cause pulmonary diseases, in a manner similar to asbestos. In the present study, mouse macrophages (J774.1) were exposed to highly-purified multi-walled CNTs (MWCNTs, 67 nm) or to UICC crocidolite in order to evaluate the toxicity of these nano-size fibers. The cytotoxicity of MWCNTs was found to be higher than that of crocidolite. The toxic effect of MWCNTs was not affected by N-acetylcysteine, an antioxidant, or buthionine sulfoximine, a glutathione synthesis inhibitor. cDNA microarray analyses suggested that the cytotoxicity of MWCNTs could not be explained satisfactorily by either an increase or decrease of gene expression, although mRNA levels of some cytokines were slightly increased by MWCNTs. Moreover, MWCNTs did not significantly activate either MAP kinases such as ERK, JNK and p38, nor common apoptosis pathways such as caspase 3 and PARP. Electron microscopic studies indicated that MWCNTs associate with the plasma membrane of macrophages and disrupt the integrity of the membrane. Several proteins were found to adsorb onto MWCNTs when MWCNT-exposed macrophages were gently lysed. One of these proteins was macrophage receptor with collagenous structure (MARCO). MARCO-transfected CHO-K1 cells associated with MWCNTs more rapidly than mock-transfected cells. These results indicate that MWCNTs probably trigger cytotoxic effects in phagocytotic cells by reacting with MARCO on the plasma membrane and rupturing the plasma membrane.     

Silver nanoparticles modified carbon nanotube paste electrode for simultaneous determination of dopamine and ascorbic acid

A novel modified carbon-paste electrode was employed for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) with good selectivity and high sensitivity. Silver nanoparticle and carbon nanotube modified carbon-paste electrode (Ag/CNT–CPE) displayed excellent electrochemical catalytic activities towards dopamine (DA) and ascorbic acid (AA). The oxidation overpotentials of DA and AA were decreased significantly compared with those obtained at the bare CPE. Differential pulse voltammetry was used for the simultaneous determination of DA and AA. The peak separation between DA and AA was 67 mV. The calibration curves for DA and AA were obtained in the range of 8.0 × 10⁻⁷–6.4 × 10⁻⁵ M and 3.0 × 10⁻⁵–2.0 × 10⁻³ M, respectively. The lowest detection limits (S/N = 3) were 3.0 × 10⁻⁷ M and 1.2 × 10⁻⁵ M for DA and AA, respectively. Method was applied to the determination of DA and AA in real samples.     

The assemble of the multi-wall carbon nanotubes on the surface of C18 and its electrochemiluminescence analytical application

In this paper, it was found that the multi-wall carbon nanotubes (MWNTs) could be effectively assembled on the surface of C18 based on the strong hydrophobic interaction between MWNTs and C18. It was further found that, when the MWNTs/C18 composite was doped into the carbon paste microelectrode, it offered the powerful ability not only as the solid phase extraction materials but also as the conducting pathway to accelerate the electron exchange between the analyte, which were extracted and located within the C18 microparticles, and the electrode surface. Based on those findings, isoniazid was used as the model analyte to explore the electrochemiluminescence (ECL) analytical performance of this composite. Experimental results revealed that the composite showed rapid extraction process of isoniazid due to the powerful absorption ability of C18 and rapid electrochemical desorption process due to the conducting pathway effect of MWNTs. The highly selective and sensitive ECL determination of isoniazid was also achieved at MWNTs/C18 composite modified micro-carbon-paste electrode. Under the optimal experimental conditions, the ECL intensity was linear with the concentration of isoniazid in the range of 5.0 × 10^-8–9.0 × 10^-6 g/mL. The detection limit was 8.0 × 10^-9 g/mL. The proposed method has been successfully applied to the determination of isoniazid in the urine samples.     

单壁纳米碳管对小鼠内脏损伤的初步研究

 目的 本研究应用无修饰的单壁纳米碳管 (naked single wall nanotube, NSWNT) 对小鼠灌胃,探讨单壁纳米碳管 (single wall nanotube , SWNT) 的生物安全性。 方法 SWNT 分别以 50 , 100 , 150 mg·kg^-1 剂量对小鼠进行灌胃给药,连续给药 10 d 后,于末次给药 30 min 后,小鼠眼球取血及小鼠内脏采集 , 进行血液生化检查及组织切片的光学显微镜、透射电镜检查。 结果 SWNT 可以导致丙氨酸氨基转移酶,天冬氨酸氨基转移酶,乳酸脱氢酶和肌酸激酶升高。光镜观察组织切片发现肝脏,肾脏,肺脏及胃肠道有显著的出血,充血。 结论 ① SWNT 可以导致肝脏和肾脏损伤;② SWNT 可被胃肠道吸收;③由于脑组织未被 NSWNT 损伤,推测 NSWNT 可能不能通过血脑屏障。