提出了一种简单、无标记、可再生的电化学方法研究适配体和凝血酶之间的相互作用,采用亚甲基蓝(MB)做电化学指示剂,氧化锆(ZrO2)-金纳米粒子(AuNPs)涂层修饰玻碳电极(GCE).利用金-硫键及杂交化学反应,捕获探针和适配体依次修饰到电极表面,亚甲基蓝插入到DNA上,形成适配体传感器.电极表面的DNA双链在凝血酶的存在下发生解旋,MB在DNA上的吸附量随之减少,峰电流也显著降低,达到检测凝血酶的 目的.实验显示,凝血酶在20 pmol/L～150 nmol/L的浓度范围内,峰电流的减小量随凝血酶浓度的升高而增大,检出限为20.6 fmol/L.该方法简单、灵敏、选择性好,并成功用于实际样品检测.

包装生产加工企业普遍有纸板、白卡纸等可燃性原材料.这类企业往往为了降低成本,一次性囤积较多原材料,在日常的生产管理中可能由于疏于管理,纸板、白卡纸等原料堆放不规范,相关电气安全、消防措施不到位,易发生火灾、触电事故,造成财产损失、人员伤亡等.

钢结构的设计、制作和安装向来需求旺盛,一般企业可根据客户的不同需求设计生产各种型号、规格的钢结构产品.按照目前的生产工艺水平,钢结构的设计、制作及安装过程中会产生有害毒物、粉尘和噪声等职业病危害因素.本文旨在评价某钢结构企业职业病危害现状,提出改进意见,为职业病危害防治提供参考.

文章以学院省级现代学徒制试点项目中探索和实践现代学徒制人才培养过程中存在的问题为契机，对实施过程中企业、学校、学生三方面临的困境进行全方位分析，针对实施困境提出破解策略，探索出育人的长效机制，以促进高职院校现代学徒制发展走出困境及有效落实，为保障企业、学校、学生的利益，并形成具有中国特色的现代学徒制提供参考。

本文介绍了一种基于无标记双重信号放大的简单、超灵敏的配体传感器,采用电化学阻抗法检测凝血酶,用氧化还原探针[Fe(CN)6]3-4-分析表征电极表面电荷传递阻抗的变化(ΔRet),凝血酶与其适配体特异性结合,形成的"三明治"夹心结构,以及双链DNA刚性结构的增敏作用,可实现双重放大信号的作用,提高目标物的测定灵敏度.结果显示,线性范围良好,为0.02～10 nmol·L-1,检出限低,达0.22 pmol·L-1,方法简单、灵敏、特异性高,能用于人血清样品中凝血酶的检测.

近年,我国对于氧化石墨烯复合材料的制备及其应用的研究日趋增多,在此基础上本文综述了近年来氧化石墨烯复合材料的研究进展,侧重介绍材料常用制备类型及其在有机污染物处理中的情况,并根据发展现状分析目前研究中存在问题及其今后的研究方向.

In this paper, we report a simple and sensitive fluorescent biosensor for the quantitative analysis of silver ions (Ag+) by using NaYF4:Yb3+, Tm3+ upconversion nanoparticles (UCNPs). Ag+ could oxidize o-phenylenediamine (OPD) to the oxidized OPD (oxOPD) directly. The fluorescence of UCNPs can be significantly quenched by oxOPD through inner filter effects (IFE). Under the optimized conditions, the Ag+ concentration is proportional to the changes of the fluorescence intensity of UCNPs. The proposed method shows high selectivity and Ag+ could be quantitatively detected in the range of 0 to 0.5 mM with a low detection limit of 33 nM for Ag+. The selectivity and sensitivity of the detection can also be satisfactory. More importantly, this method has potential in practical application to detect Ag+ in real samples without interference.

We report a new method for detection of thrombin based on aptamer-modified cadmium tellurium nanoprobe using differential pulse voltammetry(DPV) technique.The magnetic nanoparticles were used for separation,and the CdTe nanoparticles acted as electrochemical signal marker.Through the specific recognition for thrombin,aptamer was liberated from the double-strand DNA,and bound with the thrombin to fold into a structure of G-quadruplex.The detection limit reached 0.13 pmol/L.This method is demonstrated to be simple,sensitive and low-cost and successfully applied to detection of thrombin in real samples.Furthermore,this method could also be applied to protein monitoring and disease diagnosis.

In this work, a novel and simple fluorescence method for detection of uric acid (UA) based on NaYF4:Yb(3+), Tm(3+) upconversion nanoparticles (UCNPs) is developed. The proposed method is based on the fact that uricase can oxidize uric acid to allantoin and hydrogen peroxide, which, on its turn, can oxidize o-phenylenediamine (OPD) to the oxidized OPD (oxOPD). The fluorescence of UCNPs can be significantly quenched by oxOPD through inner filter effects (IFE). Under the optimized conditions, the UA concentration was proportional to the changes in fluorescence intensity of UCNPs. A linear response was obtained over the concentration range from 20 to 850μΜ with the low detection limit of 6.7μΜ for uric acid. More importantly, this method has the potential to detect uric acid in human serum samples, suggesting the nanosensor can be used in a complex biological sample matrix.

Tumor cell apoptosis by using nanosecond pulsed electric fields (nsPEF) has a great potential in clinical tumor treatment. It is difficult to find the appropriate parameters of nsPEF which can induce substantial apoptotic tumor cells because of selectivity between apoptosis and parameters of pulse number and pulse duration. To obtain the optimum parameters of nsPEF which can achieve large proportion of apoptotic tumor cells, nsPEF with different parameters (Electric field intensity of 45 kV/cm; pulse durations are 50, 100 and 200 ns respectively; pulse numbers are 10, 30, 60 and 80, respectively; repetition frequency of 1 Hz) were performed on SKOV3 cells. The experimental results of both Annexin-V/PI staining and DNA ladder gel electrophoresis indicated that apoptosis of tumor cells was pulse duration and number-dependent. With constant electric field intensity of 45 kV/cm, nsPEF of 100 ns duration and 30 pulses caused substantial tumor cell apoptosis with few necrotic cells and maximum caspase-3 activation.

Successful development of an ultrasensitive and highly specific electrochemical aptasensor for thrombin based on amplification of aptamer-gold nanoparticles-horseradish peroxidase (aptamer-AuNPs-HRP) conjugates was reported. In this electrochemical protocol, aptamer1 (Apt1) was immobilized on core/shell Fe(3)O(4)/Au magnetic nanoparticles (AuMNPs) and served as capture probe. Aptamer2 (Apt2) was dual labeled with AuNPs and HRP and used as detection probe. In the presence of thrombin, the sandwich format of AuMNPs-Apt1/thrombin/Apt2-AuNPs-HRP was fabricated. Remarkable signal amplification was realized by taking the advantage of AuNPs and catalytic reactions of HRP. Other proteins, such as human serum albumin, lysozyme, fibrinogen, and IgG did not show significant interference with the assay for thrombin. Linear response to thrombin concentration in the range of 0.1-60 pM and lower detection limit down to 30 fM (S/N=3) was obtained with the proposed method. This electrochemical aptasensor is simple, rapid (the whole detection period for a thrombin sample is less than 35 min), sensitive and highly specific, it shows promising potential in protein detection and disease diagnosis.

Tumor cells apoptosis induced by nanopulses has a great potential in clinical tumor treatment.It is difficult to find appropriate parameters of nanopulses because of the selectivity between apoptosis rate induced by nanopulses and parameters of nanopulses such as field intensity and pulse width etc.To obtain the appropriate parameters of nanopulses which can induce effective tumor cell apoptosis,different parameters of nanopulses(voltage amplitude is 9 kV;pulse duration are 1,50,100 and 200 ns respectively;pulse number are 10,30,60 and 80 respectively;repetition frequency is 1 Hz) were tested on SKOV3 cells.AnnexinV/PI was used to test early stage apoptosis rate and necrosis rate of tumor cells,while DNA ladder gel electrophoresis was used to detect late stage apoptosis of tumor cells.AnnexinV/PI and DNA ladder gel electrophoresis experiments indicate that,window effects of nanopulses on cell early stage apoptosis exist,and nanopulses with the parameters of 100 ns duration and 30 pulses can achieve the highest apoptosis and necrosis rate difference.

In order to study the mitochondrial signaling pathways of tumor cell apoptosis induced by nanosecond pulsed electric fields(nsPEF),nsPEF with specific parameters were performed on SKOV3 cells,then changes of reactive oxygen species(ROS) mitochondrial trans-membrane potential(MTMP) were tested by flow cytometry;releases of mitochondrial membrane space apoptosis-related proteins were studied by immunofluorescence;expressions or activations of mitochondrial membrane space apoptosis-related proteins were tested by Western blot.The experimental results showed that ROS increased instantly,and MTMP reduced to the minimum value 6 h after nsPEF;mitochondrial membrane space apoptosis-related proteins released to cytoplasm(P 0.05),and expressions of these proteins were higher than the control group(P 0.05).The results indicate that mitochondrial apoptosis signaling pathway exists and plays an important role in tumor cell apoptosis with nsPEF.

Covalent tethering of cysteamine to chitosan using glutaraldehyde yields thiol-functionalized chitosan (CS-SH). It was cast on a glassy carbon electrode which is found to be very stable in acidic solutions and to possess a strong affinity for Hg(II) ions as confirmed by quartz crystal microbalance measurements. A glassy carbon electrode modified with a nanocomposite made from CS-SH and multiwalled carbon nanotubes was applied for square wave voltammetric determination of Hg(II). The procedure comprises the steps of (a) chemical accumulation of Hg(II) under open-circuit condition and (b) electrochemical determination of Hg(II). Linear responses are obtained in the range from 10 to 140 nM, with a limit of detection of 3 nM (S/N = 3) under optimized conditions. The electrode was applied to the determination of Hg(II) in water samples with satisfactory recoveries.

Objective:To investigate the effect of nanosecond pulsed electric fields(nsPEF)on apoptosis and Bcl-2/Bax expression in SKOV3 cells.Methods:SKOV3 cells were exposed to the 100ns,50kV/cm,10,30,60 and 80 pulses(as the treated groups),Annexin V/PI double-stain and flow cytometry were used to assay early stage apoptosis.Agarose gel electrophoresis was used to detect DNA ladder after 6 h treated with nsPEF;Western blot was used to measure the level of cleaved caspase-3,Bcl-2 and Bax after exposing to 100ns,50kV/cm,30 pulses electric field at 0,2,6 and 12 h,respectively.Results:Compared with the control group,phosphatidylserine externalized(P<0.05),and a typical DNA ladder pattern of internucleosomal fragmentation was observed,expression of cleaved capase-3 and Bax was increased(P<0.05);Bcl-2 and Bcl-2/Bax ratio decreased(P<0.05)in nsPEF-treatment groups.Conclusion:caspase-3 dependent apoptotic pathway and the decrease in Bcl-2/Bax ratio may be involved in the apoptosis induced by the nsPEF.

In order to study the apoptosis-induction effects of exponential decay nanosecond pulsed electric fields (EDnsPEF) in vivo, tumor models in 20 female BALB/c nude mice were established by inoculating them with human melanoma cells A375. These mice were randomly divided into treated group (exposed to EDnsPEF with intensity of 20 kV/cm and duration of 300 ns) and control group equally. Twenty days later, tumor growth in the treated group was effectively inhibited (P < 0.01 compared with that in control group), typical morphological apoptosis characteristics in ultrastructure were observed by transmission electron microscope, and expression of caspase-3 and caspase-3 messenger ribonucleic acid were obviously increased (P < 0.01) using immunofluorescence and RT-PCR, respectively. These experimental results contributed evidence of tumor-growth inhibition by EDnsPEF exposure in vivo. The mechanism was apoptosis-induction effects of EDnsPEF on cancer cells by activating caspase-3. This study presented in vivo evidence of caspase-3 activation for apoptosis-induction effects of EDnsPEF, and this supported possible drug-free tumor therapy utilizing EDnsPEF.

Binding reaction of polydatin with lysozyme is studied by steady fluorescence spectroscopy in physiological medium.Polydatin can remarkably quench the fluorescence intensity of lysozyme.It is conformed from fluorescence data that the quenching effect of polydatin on lysozyme fluorescence is a single static quenching process.The binding constants KA and binding site numbers n at 298 K and 308 K in terms of Lineweavre-Burk and double-logarithm equation respectively are also obtained,which are similar at different temperatures.Synchronous fluorescence spectroscopy show that the binding of polydatin with lysozyme lead to a change of the structure of lysozyme.Hydrophobic interaction and hydrogen bonding play a major role in the reaction of polydatin with lysozyme according to the thermodynamic parameters analyzing.The distance r between donor(lysozyme) and acceptor(polydatin) is estimated to be 3.71 nm according to Frster theory of non-radioactive energy transfer.

The interaction between bovine serum albumin(BSA) and nobiletin(NOB) and its thermodynamic characteristics were investigated by multi-spectroscopy in physiological medium.The results showed that NOB could quench the fluorescence of BSA with a static quenching mechanism.The apparent binding constants and the number of binding sites at different temperatures and different pH values were estimated according to Stern-Volmer equation and double logarithmic equation,respectively.The binding constant of NOB to BSA was also estimated at room temperature using UV-Vis method,which is similar to that obtained by fluorescence analysis.The thermodynamic parameters △H and △S were estimated as 55.91 kJ·mol-1 and 274.61 J·mol-1·K-1,indicating that the hydrophobic force of NOB and BSA is mainly interaction force.The fluorescence quantum yield of BSA was calculated as 0.074.According to Frster theory,the energy transfer efficiency and the binding distance of NOB to BSA were 0.27 and 1.76 nm,respectively.Synchronous fluorescence spectra of BSA indicated that NOB didn't affect the conformation of BSA.

The interaction of nicotinamide (NA) and bovine serum albumin (BSA) was studied by fluorescence and absorption spectroscopy at different temperatures. The results revealed that NA caused the fluorescence quenching of BSA through a static quenching procedure. The binding constants KA, and the number of binding sites n, corresponding thermodynamic parameters ΔG, ΔH, ΔS between NA and BSA at different temperatures were calculated. The primary binding pattern between NA and BSA was interpreted as hydrophobic interaction. In addition, the effect of NA on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. The binding average distance, r between the donor (BSA) and acceptor (NA) was determined based on the Förster's theory and it was found to be 3.1nm.