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A new strategy is proposed based on inhibition of ion transport by lipid bilayer derived from spontaneous assembly of lipopolysaccharides (LPS), thereby a colorimetric method is established for analysis of LPS. At acidic pH values, LPS can specially bind with aminophenylboronic acid modified assembled magnetic nanospheres (APBA/AMNSs), resulting in formation of lipid bilayer around APBA/AMNSs. Under acidic condition, the lipid bilayer can inhibit the release of iron ions from AMNSs into the solution so as to decrease the oxidized extent of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt mediated by hydrogen peroxide. Using the established method, LPS can be detected over the wide linear detection range with the low detection limit. With good selectivity, reproductivity, and simplicity, the method is accurate in LPS tests of real drinking samples.

This report investigated the effect of carbon nanomaterials, single-wall carbon nanotube (SWCNT) and graphene oxide, on fibrillation of β-amyloid 40 (Aβ40) based on surface plasmon resonance (SPR) and molecular dynamics (MD). MD simulations are carried out in order to reveal the molecular mechanisms of the interaction between nanomaterials and Aβ40. The strong interaction between Aβ40 and nanomaterials is related to Van der Waals forces and the Coulomb force, inducing delicate manipulation of the main bonding energy for fibrillation of Aβ40. The interaction energy between the Aβ peptide and graphene is higher than that of SWCNT. Experimental results show both carbon nanomaterials enhance the appearance of a critical nucleus for nucleation of peptide fibrils. Graphene is more beneficial to assist the nucleation process than SWCNT. Combination of SPR and molecular dynamics could be a high-throughput method to screen protein fibrillation.

Accurate diagnosis of breast cancer cells is important on determining the stage of the disease and designing the suitable therapies. Herein, we report a sensitive biosensor based on surface plasmon resonance (SPR) spectroscopy using magnetic nanoparticle (MNP) and a two-marker recognition system. While the target breast cancer cells (MCF-7) are captured by MUC1 aptamer on the surface selectively, folic acid conjugated monodisperse MNP is used as the second selective binding reagent to form a sandwich SPR assay. The signal of SPR was enhanced significantly. This enhancement was mainly attributed by the larger mass and higher refractive index of the MNP nanoparticles located in the evanescent field. The detection limit can be achieved as low as 500 cells mL −1 . This work may afford a new model to improve the sensitivity and selectivity of SPR biosensors for large-size analytes.

In this paper, a wind turbine tower with a hub height of 60m is taken as the research object, and its wind-induced fatigue analysis is carried out. First, the general method of wind-induced fatigue analysis of the wind turbine tower is given. The maximum stress time history curve of the tower is calculated by the time history analysis method. The stress amplitude, the mean value and the cycle times of the stress time history are counted by the rain-flow counting method. Finally, the fatigue life of tower is calculated by linear damage theory. According to the study, the fatigue life of the wind turbine is greater than that of the design service life, and it can meet the requirements of the design. The influence of wind load on the fatigue damage of the tower is different from the wind load of different wind speed and wind direction.

Graphene, a single atom thick and two dimensional carbon nano-material, has been proven to possess many unique properties, one of which is the recent discovery that it can interact with single-stranded DNA through noncovalent π–π stacking. In this work, we demonstrate that a new strategy to fabricate many kinds of biosensors can be developed by combining this property with cascade chemical reactions. Taking the fabrication of glucose sensor as an example, while the detection target, glucose, may regulate the graphene–DNA interaction through three cascade chemical reactions, electrochemical techniques are employed to detect the target-regulated graphene–DNA interaction. Experimental results show that in a range from 5 μM to 20 mM, the glucose concentration is in a natural logarithm with the logarithm of the amperometric response, suggesting a best detection limit and detection range. The proposed biosensor also shows favorable selectivity, and it has the advantage of no need for labeling. What is more, by controlling the cascade chemical reactions, detection of a variety of other targets may be achieved, thus the strategy proposed in this work may have a wide application potential in the future.

Protein-DNA interaction plays important roles in many cellular processes, and there is an urgent demand for valid methods to monitor the interaction. In view of this, we propose a simple label-free colorimetric platform for the detection of protein-DNA interaction. Protein-DNA couples together with peroxidase-mimicking DNAzyme and exonuclease are elaborately incorporated into an integrated biosensing system. Besides the simplicity and efficiency, the strategy also has a great advantage for its universality in the detection of different protein-DNA couples. In our experiments, effective validation of our approach can be supported by two different protein-DNA couples (estrogen receptor α and nuclear factor kappa B). Experimental results show that the DNAzyme is competent to give rise to evident readout signals to monitor protein-DNA couples. Furthermore, with the substitution of DNA binding sequence in the probe, this method could be extended to a general platform for the detection of protein-DNA interaction.

Breast cancer is one of the most critical threats to the health of women, and the development of new methods for early diagnosis is urgently required, so this paper reports a method to detect Michigan cancer foundation-7 (MCF-7) human breast cancer cells with considerable sensitivity and selectivity by using electrochemical technique. In this method, a mucin 1 (MUC1)-binding aptamer is adopted to recognize MCF-7 human breast cancer cells, while enzyme labeling is employed to produce amplified catalytic signals. The molecular recognition and the signal amplification are elaborately integrated by fabricating an aptamer-cell-aptamer sandwich architecture on an electrode surface, thus a biosensor for the detection of MCF-7 is fabricated based on the architecture. The detection range can be from 100 to 1×10(7) cells, and the detection limit can be as low as 100 cells. The method is also cost-effective and conveniently operated, implying potential help for the development of early diagnosis of breast cancer.

The incidence of cardiac arrhythmia and heart failure continues to rapidly increase, leading to a growing epidemic which constitutes a serious financial burden for society (Chugh et al., 2014; Melman et al., 2014). Despite the standard therapeutic strategies to treat adverse cardiac remodeling that precedes the development of arrhythmia and overt heart failure, their prevalence is still increasing and their morbidity and mortality have not been largely improved (Melman et al., 2014; Sardar et al., 2014). Continued and deeper understanding of the molecular mechanisms responsible for arrhythmia and heart failure will help identify novel effective therapies. In the past few years, research has implicated the contribution of genetic and epigenetic factors to arrhythmia and heart failure. This research hot topic entitled “Genetic and epigenetic basis of arrhythmia and heart failure” provides a snapshot in this area. The 10 selected papers in this special research topic will enhance current understanding of the genetic and epigenetic basis of arrhythmia and heart failure, and also will expand our knowledge on novel interventions. In this issue, genetic aspects of arrhythmia were described by 3 different groups. Crump and Abbott (2014) provided an update about arrhythmogenic KCNE gene variants and their roles, Nielsen et al., (2013) showed that the Ito regulatory subunit Klf15 was not associated with early-onset long atrial fibrillation in their cohort. Besides familial atrial fibrillation, genome wide association studies (GWAS) have identified common variants in the general population for atrial fibrillation. Yao et al. (2014) gave an overview on the paired-like homeodomain 2, which was identified as a common variant to be involved in atrial fibrillation, highlighting the potential of paired-like homeodomain 2 as a new therapeutic target. Duygu et al. (2013) provided an outstanding overview about the genetics and epigenetics of arrhythmia and heart failure. Besides highlighting specific genetic mutations associated with heart failure, they also summarized epigenetic mechanisms including DNA methylation, ATP-dependent chromatin remodeling, histone modification and RNA-based mechanisms, highlighting the relationship among epigenetics, heart failure and arrhythmiaogenesis. Finally, they also introduced a discussion on the role of non-coding RNAs especially microRNAs (miRNAs, miRs) in heart failure and arrhythmia. miRNAs are endogenous non-coding RNAs which post-transcriptionally regulate gene expressions (Condorelli et al., 2014). A single miRNA can target several target genes while an individual gene can be regulated by many miRNAs (Viereck et al., 2014). Therefore, miRNAs have been considered as central regulators of gene expression, which participate in many essential biological processes including cellular proliferation, differentiation, apoptosis, and cardiac metabolism (Condorelli et al., 2014; Viereck et al., 2014). Dysregulations of miRNAs have been connected to many cardiovascular diseases, including arrhythmia and heart failure (Kwekkeboom et al., 2014; Melman et al., 2014). In this special research topic, 4 opinion articles have been provided about miRNAs in arrhythmia and heart failure. Fu et al. (2014) presented the current understanding about miRNAs as novel players in atrial fibrillation, a most common form of arrhythmia that affects at least 1% persons in the general population. Changes in cardiac structure and function (termed diabetic cardiomyopathy) may play a role in the increased incidence of sudden death and heart failure in the diabetic patients. Zhou et al. (2014) summarized dysregulations of miRNAs in diabetic cardiomyopathy. Interestingly, changes of circulating miRNAs in diabetic patients have also been noted, although their associations with diabetic cardiomyopathy are unclear. Better understanding of circulating miRNAs in diabetic cardiomyopathy would help the development of biomarkers and novel therapies. Ageing is correlated with an increase in the incidence of both heart failure (particularly heart failure with preserved ejection fraction) and atrial fibrillation. Considering the rapid increase in the geriatric population, it is urgent to understand the role of miRNAs in aging. Zhuo et al. (2014) provided some insights into the dysregulation of miRNAs in aging-related heart failure. New therapeutics via targeting microRNAs are being developed based on the detailed understanding of the role of miRNAs in heart failure and arrhythmia using either antagomirs or mimics (Kwekkeboom et al., 2014). In contrast to the previous articles on the role of miRNAs in pathological heart diseases, Fu et al. (2013) dissected the role of miRNAs in physiological hypertrophy. Physiological hypertrophy, which is associated with exercise and pregnancy, is not associated with pathological processes like apoptosis and fibrosis, and unlike its counterpart (pathological hypertrophy), is not the harbinger of sudden death or heart failure. Given the known beneficial effects of exercise on cardiovascular outcomes, a better understanding of miRNAs in physiological hypertrophy may lead to novel miRNA-based therapies for heart failure. Finally Stagnaro and Caramel (2013) proposed a “Quantum Biophysics Semeiotics” (QBS) microcirculatory theory of atherosclerosis, which could be used for diagnosis or therapies. In addition, Tao et al. (2013) provided their prospects of using Qiliqiangxin, a traditional Chinese medicine, in the treatment of heart failure potentially through epigenetic regulation of regeneration. In conclusion, this research topic offers a detailed and updated summary about genetic and epigenetic basis of arrhythmia and heart failure, and provides a forum for discussion on ways to translate these genetic and epigenetic findings into novel therapies for arrhythmia and heart failure.

In this paper, we have proposed a new electrochemical aptasensor based on a novel ligase-assisted Exo III-catalyzed degradation reaction (LAECDR), which consists of DNA ligase-catalyzed ligation of thrombin-binding aptamer (TBA) with an extension strand (E-strand) and Exo III-catalyzed selective degradation of probe DNA, by using an improved target-induced strand displacement strategy. As a result of LAECDR, methylene blue (MB)-labeled mononucleotides can be released from the 3'-terminal of probe DNA and captured by cucurbit[7]uril-functionalized electrode to induce noticeable electrochemical response. Nevertheless, in the presence of the target protein, thrombin, the TBA that is partially complementary to probe DNA is preferentially binding with the target protein, thereby inhibiting LAECDR from taking place. The remaining intact probe DNA will prevent the terminal-attached MB from approaching to the electrode surface due to strong electrostatic repulsion, so the electrochemical response will be changed by thrombin. By tracing the electrochemical response of adsorbed MB, our aptasensor can exhibit high sensitivity for thrombin detection with a wide linear range from 100 fM to 1 nM and an extremely low detection limit of 33 fM, which can also easily distinguish thrombin in the complex serum samples with high specificity. Therefore, our aptasensor might have great potential in clinical applications in the future.

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis. It has been identified as an ideal biomarker for staging of many kinds of cancers, so more specific and intense signal is desirable for VEGF biosensors so that the sensors may have more valuable clinical application. Herein, we report a highly sensitive and selective surface plasmon resonance (SPR) sensor for VEGF detection by using two DNA aptamers which target different VEGF domains used as the capture and detection probe, respectively. Moreover, by making use of carboxyl-coated polystyrene microspheres, 3'-NH2 immobilized aptamer and 3'-NH2 modified primer DNA are loaded through amidation onto the sensing layer for further rolling circle amplification (RCA) process to amplify the SPR signal. With the well-designed sensing platform, VEGF can be determined in a linear range from 100 pg mL(-1) to 1 μg mL(-1) with a detection limit of 100 pg mL(-1). Due to its high specificity and desirable sensitivity, this RCA assisted SPR method may be a useful tool for the assay of VEGF in the future. What is more, by replacing the sensing element, i.e., the aptamer of VEGF used in this work, more biosensors for sensitive detection of other biomarkers proteins can be fabricated based on the strategy proposed in this study.

A novel strategy to fabricate an aptasensor for potassium with high sensitivity and selectivity by using nicking endonuclease is proposed in this work. A nicking endonuclease (Nt.CviPII), which may recognize specific nucleotide sequences in double-stranded DNA formed by a potassium-binding aptamer and a linker DNA but cleave only the linker strand, may transfer and amplify the quantitative information of the potassium detection to that of the linker DNA through elaborate strand-scission cycles. Since the technique for gene assay is much more mature, the linker DNA can thereby be detected by a number of available methods. Here, taking advantage of a simple and fast gold nanoparticles-based sensing technique, we are able to assay the linker and consequently potassium ion simply by UV-vis spectroanalysis and even with the naked eye. Results show that a 2 μL sample containing 0.1 mM of potassium is enough to induce distinct color appearance of the nanoparticles, and the potassium ion can be easily distinguished from many other ions. The strategy proposed in this work shows some unique advantages over some traditional methods and may be further developed for the detection of some other chemicals in the future.

The organic reef is a special type of carbonate reservoir which always dominates the spatial distribution, reserves and accumulations of natural gas. However, it is difficult to determine the organic reef’s internal structure and gas reservoirs due to numerous adverse factors such as the low resolution of seismic data, depth of burial, strong anisotropy, irregular spatial distribution and complex internal structure. A case study of wavelet decomposition and reconstruction technology applied to elucidate the features of organic reef reservoirs in the Changxing formation from Yuanba gas field shows that the seismic record reconstructed by high frequency signal can adequately describe the internal properties of organic reef reservoirs. Furthermore, the root mean square amplitude ratio of both low and high frequency data obtained from the reconstructed seismic data clearly show spatial distribution of gas and water in reef reservoirs.