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Summary paragraphThe elucidation of gene-silencing mechanisms by RNA interference (RNAi) and antisense oligomers has drawn increasing attention to nucleic acid medicine. However, several challenges remain to be overcome, such as in vivo stability1, target selectivity2,3, drug delivery4,5, and induced innate immunity6. Here, we report a new, versatile, and highly-selective method to hack RNA by controlling RNA structure using short oligonucleotides (RNA hacking: RNAh) in living cells. The oligonucleotide, named Staple oligomer, hybridizes specifically to a target mRNA and artificially induces an RNA higher-order structure, RNA G-quadruplex (RGq)7, on the mRNA. As a result, the RGq allows effective suppression of the target protein translation. This technology does not require cooperation with bioprocesses including enzymatic reactions as in RNAi or antisense technologies, permitting the introduction of artificial nucleic acids into Staple oligomers to increase their in vivo stability without compromising their effectiveness. The method was validated by translational regulation of the mRNAs of TPM3, MYD88, and TRPC6, in a cell-free system and in living mammalian cells. In vivo application of the technology to TRPC6 mRNA allowed us to prevent cardiac hypertrophy in transverse aortic constriction (TAC)-treated mice with no detectable off-target effects. This technology provides new insights into gene therapy after RNAi and antisense technologies.

Tandem repeats of guanine-rich sequences in RNA often form thermodynamically stable four-stranded RNA structures. Such RNA G-quadruplexes have long been considered to be linked to essential biological processes, yet their physiological significance in cells remains unclear. Here, we report a approach that permits the detection of RNA G-quadruplex structures that modulate protein translation in mammalian cells. The approach combines antibody arrays and RGB-1, a small molecule that selectively stabilizes RNA G-quadruplex structures. Analysis of the protein and mRNA products of 84 cancer-related human genes identified Nectin-4 and CapG as G-quadruplex-controlled genes whose mRNAs harbor non-canonical G-quadruplex structures on their 5′UTR region. Further investigations revealed that the RNA G-quadruplex of CapG exhibits a structural polymorphism, suggesting a possible mechanism that ensures the translation repression in a KCl concentration range of 25–100 mM. The approach described in the present study sets the stage for further discoveries of RNA G-quadruplexes.

Hydrogen sulfide (H2S) formed during sulfur metabolism in bacteria has been implicated in the development of intrinsic resistance to antibacterial agents. Despite the conversion of H2S to hydropersulfides greatly enhancing the biochemical properties of H2S such as antioxidant activity, the effects of hydropersulfides on antibiotic resistance have remained unknown. In this work, we investigated the effects of H2S alone or together with cystine to form cysteine hydropersulfide (CysSSH) on the activities of antibacterial agents. By using the disc diffusion test, we found that CysSSH treatment effectively inactivated β-lactams of the penicillin class (penicillin G and ampicillin) and the carbapenem class (meropenem). These β-lactams were resistant to treatment with H2S alone or cystine alone. In contrast, cephalosporin class β-lactams (cefaclor and cefoperazone) and non-β-lactam antibiotics (tetracycline, kanamycin, erythromycin, and ofloxacin) were stable after CysSSH treatment. Chromatographic and mass spectrometric analyses revealed that CysSSH directly reacted with β-lactams to form β-lactam ring-opened carbothioic S-acids (BL-COSH). Furthermore, we demonstrated that certain bacteria (e.g., Escherichia coli and Staphylococcus aureus) efficiently decomposed β-lactam antibiotics to form BL-COSH, which were transported to the extracellular space. These data suggest that CysSSH-mediated β-lactam decomposition may contribute to intrinsic bacterial resistance to β-lactams. BL-COSH may become useful biomarkers for CysSSH-mediated β-lactam resistance and for investigation of potential antibacterial adjuvants that can enhance the antibacterial activity of β-lactams by reducing the hydropersulfides in bacteria.

A fluorescent dye-labeled DNA probe was adsorbed and quenched on the monolayer of RuO2 nanosheets. Significant fluorescent recovery was observed upon the addition of complementary DNA due to desorption of the probe from the surface of the RuO2 nanosheet through duplex formation. The efficiency of fluorescence recovery was higher than that for graphene oxide, which was known as a quencher-free platform for the detection of nucleic acids in a homogeneous solution.

Two DNA conjugates modified with ethylenediaminetetraacetic acid and 1,10-phenanthroline were prepared as a pair of split probes. They were designed to form a duplex with their auxiliary groups facing each other, providing a microenvironment to accommodate lanthanide ions. The luminescent signal was amplified by catalytic duplex formation based on an entropy-driven DNA circuit.

It is known that some fluid particles may be transported chaotically in Lagrangian description although the velocity field seems to be stable in Eulerian description. A typical example can be found in the system of two-dimensional Rayleigh-Benard convection with perturbed velocity fields, which has been investigated as a low dimensional mechanical model of fluid phenomena associated with natural convection in order to clarify the mechanism of fluid transport (see, for instance, [2]). In this study, we make an experimental study on the global structures of chaotic mixing appeared in the two-dimensional perturbed Rayleigh-Benard convection by analyzing Lagrangian coherent structures (LCSs), which correspond to the invariant manifolds of time-dependent mechanical systems. We develop an apparatus to measure the velocity field by Particle Image Velocimetry (PIV) and then show the LCSs which can be numerically detected from the experimental data by computing Finite-time Lyapunov exponent (FTLE) fields. Finally, we show the global structures of chaotic mixing appeared in the perturbed Rayleigh-Benard convection as well as the steady convection by experiments. In particular, we clarify how the LCSs are entangled with each other around the cell boundaries to carry out chaotic Lagrangian transports.

Cooperative recognition of a repetitive sequence was performed with a short single DNA strand consisting of duplex- and triplex-forming regions modified with a ligand (benzoquinoquinoxaline) to stabilize a triplex structure. The former region was complementary with one unit of a repetitive sequence and the latter had a sequence that can bind with a cognate duplex formed by another DNA molecule bound on an adjacent site. The DNA binding to one unit of the repetitive sequence is expected to facilitate the second binding to an adjacent unit through cooperative triplex formation. The cooperativity was confirmed by evaluation of thermal stabilities of the complexes with a series of model repetitive sequences.

DNAs can act as flexible interfaces for arranging particular reactant partners such as biomolecules and other functional molecules modified on DNAs in close proximity to increase their effective concentrations. Here, we focused on dynamic programmability of the DNA structure based on sequence-specific autonomous strand exchange reactions triggered by an initiator DNA, i.e., DNA circuits, to achieve a catalytic reaction providing physical and chemical signals. For analytical applications, DNA-templated formation of luminescent lanthanide (Ln) complexes was combined with the described amplification system. An appropriate microenvironment for the accommodation of a lanthanide ion [Ln(III)] was constitutively generated by ethylenediaminetetraacetic acid (a chelator) and 1,10-phenanthroline (a sensitizer) tethered to the ends of assembled DNAs to form a luminescent complex. For DNA circuits, we used hybridization chain reaction and catalytic hairpin assembly to construct linear and cruciform DNA structures, respectively, as scaffolds of Ln cluster formation. Both systems were designed for complex formation at every site where the ends of constituent DNAs faced each other on the DNA scaffolds by addition of an initiator. After optimization of the reaction conditions, amplified luminescence of a Tb(III) complex was obtained, which implies formation of a large number of complexes after addition of the initiator DNA. The formation of lanthanide complex clusters can be simply governed by the thermodynamics of duplex hybridization, which can be rationally controlled by well-established parameters such as the DNA length and sequence, concentration, temperature, and ionic strength. The emission color of the Ln cluster can be easily changed by choosing Ln ions with the desired color. The principle behind this technique is simple; therefore, it can be applied to various catalytic DNA-templated reactions by replacing lanthanide complex ligands by other functional molecules and materials.

Two-dimensional (2D) nanomaterials are attracting increasing research interest because of their unique properties and promising applications. Here, we report a facile method to manipulate the assembly of nanoparticles (NPs) to fabricate free-standing 2D quasi-nanosheets. The as-generated 2D products are composed of few-layer NPs; that is, their thicknesses are only tens of nanometers but lateral dimensions could be up to several micrometers. Therefore, the novel structure was denoted as 2D “quasi-nanosheets (QNS)”. Specifically, several types of building blocks could be assembled into 2D unary, binary, ternary, and even quaternary QNS by a universal procedure. The entire assembly process is carried out in solution and mediated simply by tuning the concentration of ligands surrounding the NPs. In contrast to traditional assembly techniques, even without any substrate or template, these QNS showed exceptionally high stability. They can remain intact for several days without any disassembly regardless of the solvent environment (e.g., water, ethanol, methanol, and hexane). In general, our method has effectively tackled several limitations associated with traditional assembly techniques and allows more freedom in manipulating assembly of NPs, which may hold great potential for future fabrication of 2D devices with rich functionalities.

The electrochemical signal from ferrocene on a DNA probe was successfully modulated in a homogeneous solution by the template-directed formation and dissociation of an inclusion complex with β-cyclodextrin on another probe. The electrochemical response was amplified by combining with a DNA circuit, in which the target DNA served as a catalyst. This system did not require any modification of a complementary DNA with the ferrocene-modified probe on the electrode surface to separate the bound/free probe for the detection of 200 nM target DNA.

Cancer cell count in the blood of cancer patients is extremely low. If these cells are easily detectable, cancer diagnosis may be possible by simply using a blood test, thus reducing patient burden. This study aimed to develop a cancer detection device by combining a microfilter that can be dynamically deformed and a nucleic acid aptamer that has a specific binding ability to cancer cells for easy detection. The cancer detection device was fabricated by photolithography, electroforming, and three-dimensional printing. The cancer cell detection ability of the fabricated device was evaluated using 1 mL of blood samples spiked with different concentrations of cancer cells. The lowest concentration of cancer cells in the blood was 5 cancer cells/1 mL blood. The fabricated microfilters specifically detected cancer cells in the blood successfully at exceedingly low concentrations. Moreover, the cancer detection experiment results using human whole blood revealed that cancer detection could be performed with higher accuracy using the fabricated cancer detection device compared to pre-existing cancer detection equipment (e.g., CellSearch system, Veridex). These findings provide important insights into the use of cancer cells in the blood as a diagnostic approach for cancer.

In forensics, body fluid identification plays an important role because it aids in reconstructing a crime scene. Therefore, it is essential to develop simple and reliable techniques for body fluid identification. Nucleic acid aptamers are useful tools in analytical chemistry that can be used to improve conventional forensic analytical techniques. They have numerous advantages over antibodies including their low cost, long shelf life, and applicability for chemical modification and PCR amplification. A DNA aptamer against a human prostate-specific antigen (PSA), which is a well-known protein marker for semen identification in forensics, has been reported previously. In this study, as a proof-of-concept for nucleic acid aptamer-based identification of body fluids, we developed a technique of aptamer-based PSA assays for semen identification that employed enzyme-linked oligonucleotide assay (ELONA) and real-time PCR. We evaluated their sensitivity and specificity for semen compared with those for blood, saliva, urine, sweat, and vaginal secretion. The assays have equivalent procedures compared to enzyme-linked immunosorbent assay; their results were consistent with those produced by the conventional immunochromatographic assay. The minimum volume of semen required for detection was 62.5 nL in ELONA and 5 nL in real-time PCR, making this assay applicable for semen detection in actual criminal investigation. Aptamers can be a cost-effective and versatile tool for forensic body fluid identification.

The business event sector expects large economic impact as MICE (Meeting (M), Incentive Travel (I), Convention (C), and Exhibition and Event (E)). Some guidelines for MICE sustainability include the requirement for carbon management (carbon neutral, measurement of greenhouse gas emissions, carbon offset, etc.) as a positive contribution to mitigating climate change. According to the environmental guidelines for events updated by the Japanese Ministry of the Environment in 2019, goods should be procured after considering the environmental load items and life cycle stages from the life cycle assessment (LCA) perspective. In this study, we evaluated the business events sector, not only transportation but also accommodation of participants from overseas, as well as food and beverages, souvenirs and shopping, and entertainment and tourism expenses. These items were not included in the previous existing case studies. We evaluated the carbon footprint (CFP), calculated from consumption information using input-output analysis. In this study, the total CFP was 804.8 t-CO2eq (M, I, C-ICCA (Convention based on an international conference standard from the International Congress and Convention Association (ICCA)), and E) and transportation (Transp, 56.0%) contributed the most, followed by planning and preparation (Plan, 13.2%) and accommodation (Acc, 12.0%), souvenirs, shopping, entertainment and sightseeing (SE, 10.1%), and food and beverages (FB, 7.9%). In the case of M, I, C-JNTO (Convention based on an international conference standard from the Japan National Tourism Organization (JNTO)) and E, the total CFP was 1714.4 t-CO2eq and transportation (Transp, 54.3%) contributed the most, followed by planning and preparation (Plan, 14.3%) and accommodation (Acc, 12.9%), food and beverages (FB, 9.2%), and souvenirs, shopping, entertainment and sightseeing (SE, 8.2%). From this result, the CFP of this sector was found to be due to transportation, planning and preparation, accommodation, food and beverages, and souvenirs. Sustainability guidelines recommend that organizers procure products that contribute to lower CFP, and it is considered good practice to provide participants with such product and service choices. The providers themselves also need action to offer low CFP products. Assessing changes in consumption items in future studies may help to calculate environmental impacts and sustainability.

A fluorescent dye-labeled DNA probe was adsorbed and quenched on the monolayer of RuO

Ferrocene (Fc) and β-cyclodextrin (βCyD) were modified at each end of stem-loop structured DNA as an electrochemical signal generator and its quencher, respectively, to give an electrochemical molecular beacon (eMB). A relatively high efficiency of signal quenching was achieved by an inclusion complex (βCyD ⊃ Fc) formation that was induced on the stem structure of the closed form (= stem-loop structure) of eMB. With the addition of target DNA, the structure of eMB opened to form a linear duplex, where the Fc dissociated from the βCyD to restore its intrinsic electrochemical signal. The signal contrast of the electric current for this off/on-type sensor was high, ca. 95. This technique did not require any modification of the electrode surface, and it realized the detection of the target nucleic acids in a homogeneous solution with a high sensitivity using high-performance liquid chromatography (HPLC) equipped with electrochemical detector.

Xylitol separation from a polyol mixture of the byproducts from bioethanol production processes was performed by liquid chromatography using short columns packed with lanthanide ion-loaded ion-exchange resins. Xylitol was successfully separated with sufficiently high resolution using adsorbents with medium rare-earth metal ions, such as Nd3+ and Sm3+. The adsorbents' specific nature is explained by the so-called "gadolinium break," which is known as a discontinuous behavior of thermodynamic parameters in complexation of the lanthanide series. From the observed behavior, the optimum lanthanide ions could be chosen to prepare appropriate adsorbents for ligand-exchange chromatography of given polyol mixtures.

The last several years have seen exciting advances in the understanding of the structure and function of higher-order structures of RNA. Expression levels of some specific genes were shown to be directly regulated by environmentally-responsive formation of certain secondary structures such as stem-loops and pseudoknots. Even among these noncanonical structures, RNA G-quadruplexes, which form on the regions of guanine-rich sequences in mRNA, are highly stable structures that are involved in a variety of biological processes. However, many questions regarding the biological significance of RNA G-quadruplexes remain unsettled, mainly because it is difficult to locate the structures in mRNA. This review focuses on emerging methods that locate RNA G-quadruplexes in mRNA by computational and biochemical techniques. In addition, recent reports on the biological functions of RNA G-quadruplexes are also covered to highlight their various roles in cells, such as in regulating mRNA processing and translation.

An electrochemical molecular sensor based on a new principle is reported. Nereistoxin (NRT, 4-N,N-dimethylamino-1,2-dithiolane), a naturally occurring neurotoxin (nicotinic acetylcholine receptor agonist), was adsorbed on an Au electrode via Au-S covalent bonding and accelerated the electron transfer between the electrode and the marker, ferricyanide anion. The contrast between the electrochemical responses obtained with the bare and NRT-modified Au electrodes was more pronounced at a low ionic strength of the supporting electrolyte, KCl. In the presence of 1 mM KCl, almost a 0/1 contrast between the signals was obtained through electrostatic interaction between the protonated tertiary amino group of NRT and the anionic ferricyanide ion. No current was observed with an electrode modified with mercaptopropionic acid. An unusually low ionic strength thickened the electric double layer to the degree where current was not observed with the bare electrode. The effect of the electrostatic concentration of the marker ion becomes obvious under such conditions. Commercially available NRT-related pesticides such as Cartap and Bensultap were also detected using the same format after pretreatments by hydrolysis/reduction. The present sensing method was successfully applied to human serum with satisfactory sensitivity.

(The microstructural refinement of cobalt-based alloy (Stellite No. 6) by laser cladding and friction stir processing (FSP) was studied. A nanometer-sized microstructure consisting of fine carbide (particle size: 100–200 nm) and a grain (grain size: 150–250 nm) was successfully fabricated by the FSP on the laser clad cobalt-based alloy. The nanostructured cobalt-based alloy (Stellite No. 6) had an extremely high hardness of about 750 HV.

According to the United Nations Environment Program (UNEP) annual Emissions Gap Report 2019, further reductions in greenhouse gas (GHG) emissions are needed to reduce climate change impacts. In Japan, the 2030 Intended Nationally Determined Contribution (INDC) target is an emissions reduction of 26% compared to 2013. The World Health Organization (WHO) declared that the coronavirus (COVID-19) outbreak has led to 43,341,451 confirmed cases and 1,157,509 confirmed deaths globally and affected 218 countries (as of 27 October 2020). In Japan, as of the same date, 96,948 infectious cases and 1724 deaths related to the new coronavirus had been recorded. These numbers continue to increase. In Japan, in March 2020, the number of international tourist arrivals decreased by about 93% compared to last year at the same period. The World Tourism Organization (UNWTO) reported several significant scenarios for the tourism industry. COVID-19 is the greatest shock to international tourism since 1950 and represents an abrupt end to the 10-year period of sustained growth that followed the 2009 financial crisis. It was thought that it would be possible to analyze the economic, environmental, and social impacts of rapid social changes. Thus, this study estimates changes in Japan&rsquo, s tourist consumption, the carbon footprint (CFP), and employment due to the influence of the COVID-19 pandemic. The calculations in this study adopt a lifecycle approach using input&ndash, output tables. Based on these observations, this study uses four scenarios (SR 1, no recovery until December, SR 2, recovery from October, SR 3, recovery from July or September, and SR 0, same growth rate as 2018&ndash, 2019) for Japan to calculate the CFP and employment change using input&ndash, output table analysis based on tourist consumption, which is a tourism metric. According to our results (2019 vs. SR 1 and 3), the consumption loss is between 20,540 billion yen (65.1%) and 12,704 billion yen (39.1%), the CFP reduction is between 89,488 Mt-CO2eq (64.2%) and 54,030 Mt-CO2eq (37.5%), and the employment loss is between 2,677,000 people (64.2%) and 1,678,000 people (37.5%). As of November 2020, the tourism industry continues to be affected by the COVID-19 pandemic. In the post-COVID-19 society, it will be necessary to maintain the GHG emissions reductions achieved in this short period and realize economic recovery. This recovery must also be sustainable for tourism stakeholders and society.

To study an environmental or biological solution, it is essential to separate its constituents. In this study, a 3D-deformable dynamic microfilter was developed to selectively separate the target substance from a solution. This microfilter is a fine metallic nickel structure fabricated using photolithography and electroplating techniques. It is gold-coated across its entire surface with multiple slits of 10–20 μm in width. Its two-dimensional shape is deformed into a three-dimensional shape when used for fluid separation due to hydrodynamic forces. By adjusting the pressure applied to the microfilter, the size of the gap created by deformation can be changed. To effectively isolate the target substance, the relationship between the solution flow rate and the extent of microfilter deformation was investigated. The filtration experiments demonstrated the microfilter’s ability to isolate the target substance with elastic deformation without undergoing plastic deformation. Additionally, modification of the microfilter surface with nucleic acid aptamers resulted in the selective isolation of the target cell, which further demonstrates the potential application of microfilters in the isolation of specific components of heterogeneous solutions.

A simple and cost-effective cholinesterase assay is presented. Thiocholine (TCh), which is generated from substrates by the action of cholinesterase, promotes the electron transfer between [Fe(CN)6]3–/4– and Au electrodes. The electric current increases with the TCh concentration; therefore, the current decreases when cholinesterase is inhibited by neurotoxic chemicals, such as organophosphorus and carbamate compounds. First, we monitored the responses of acetylcholinesterase to cholinesterase inhibitors. The substrate acetylthiocholine was digested with acetylcholinesterase in Tris−HCl buffer, then the reaction mixture was combined with acetonitrile. A polished Au electrode was immersed in the mixed solution for 30 s to immobilize the enzymatic hydrolysis product, TCh, on the electrode surface. The electrode was then subjected to differential pulse voltammetry in 0.5 mM [Fe(CN)6]3– in the presence of KCl as a supporting electrolyte, with a concentration as low as 1 mM. The optimum conditions for the enzymatic treatment were for 10 min at 30 °C with 1.25 mU/mL acetylcholinesterase and 100 μM acetylthiocholine as final concentrations. The inhibition of acetylcholinesterase activities from DDVP (organophosphorus) and methomyl (carbamates) could be monitored. This system was applied to human serum samples containing butyrylcholinesterase. The inhibition of butyrylcholinesterase by DDVP and methomyl were successfully monitored even in human serum. Finally, real human blood donated by 10 volunteers were subjected to a cholinesterase assay using this system. The results from the present method showed good correlation with those obtained from the conventional method using 5,5′-dithiobis-(2-nitrobenzoicacid). The present method was considered valid as a novel ChE assay for human blood.

This paper presents a three-dimensional deformable microfilter modified with a nucleic-acid aptamer for capturing of target cells. Separating and capturing target cells from the fluid is very important for health diagnosis and medical diagnosis by liquid biopsy. The presented microfilter permits the separation of arbitrary size because the opening gap of the microfilter is three-dimensionally transformed by fluidic force. The deformation of the microfilter is able to be changed by adjusting the fluidic force. Also, the presented microfilter permits the specific capturing of target cells by specifically adsorbing ability of a nucleic-acid aptamer. In this experiment, the cancer cell was used as a target cell. The nucleic-acid aptamer that has a specific adsorbing ability to epithelial cell adhesion molecules was used for capturing the cancer cell. The results of experiment, the target cells were effectively captured by nucleic-acid aptamer modified microfilter.

A potentiometric sensing platform that enables real-time DNA hybridization detection is described. A model target DNA, t37s : 5′-AAA AAA AAA AAA-(TC) 2 -Ts 5 -(TC) 2 -GGA GCT GGT GGC-3′, which consist of a dodecamer polydeoxyadenylic acid and the human K-ras oncogene, and a five-successive deoxythymidine phosphorothioate (Ts) was designed. With the gold–phosphorothioate binding, the DNA could bind the complementarily sequences to concentrate them at the gold electrode surfaces. Accordingly, a dodecamer polydeoxythymidylic acid having ferroin-moiety ( T12FeP ) and a ferrocene-modified complementary of K-ras ( KrasFc ) were synthesized. Electrochemical quartz-crystal-microbalance (QCM) using Au-sputtered quartz chips that served as the indicator electrode collected the electrode responses. When the electrode surface was treated with the T12FeP –hybridized t37s , which were subsequently oxidized to the corresponding Fe(III) form, the emf developed in a buffer solution responded to KrasFc ; with the electrode-attached t37s the redox-active DNAs could group into a pair to establish specific redox-titration equilibrium. A QCM confirmed the on-electrode titrimetry feasible by determining the initial concentration and the amount of hybridization along with the emf measurements. Although the present method is necessary for two-kinds of redox conjugation of the target DNA, it should be important as a novel framework of electrochemical gene sensing. Preliminary examples of real-time measurement were also demonstrated with the results of kinetics analysis data.

The weak affinity of bare carbon based electrodes for biological molecules or charged species is a major drawback for their direct application in analytical electrochemistry. We observed that the surfaces of graphite rods and glassy carbon (GC) ring electrodes can be modified by oxygenated functional groups through controlled electrochemical oxidation in aqueous media. Study of their cyclic voltammetry, surface conductivity, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD) spectroscopy confirmed the chemical change. In the electrodynamics study, the modified GC ring in a rotating ring-disk electrode (RRDE) assembly showed better electron transfer efficiency than the virgin electrode when evaluated using a Ru(bpy)32+/3+ couple. In comparison to the virgin electrode, the modified graphite rod exhibited better affinity toward polyvinylpyrrolidone protected reduced graphene oxide (PVP-rGO) attached to glucose oxidase enzymes (GOx), and showed the direct attachment of mediators to the oxygenated electrode surface. These observations imply that a small oxygenated layer on the carbon electrode surface can significantly increase its activity. The present evidence indicates the possibility for the oxygenous functionalization of carbon based electrodes for applications in areas like electrokinetics studies and biosensing, where strong analyte–electrode interactions are useful.

The fluorescence signal of a DNA sensor based on strand exchange on graphene oxide was amplified using a DNA circuit that consisted of autonomous cyclic reactions catalyzed by the target. Selectivi...

Modification of AISI D2 tool steel was conducted by friction stir processing (FSP). Effects of tool rotational speed on microstructural evolution and mechanical properties were investigated. Though coarse primary carbides in the size of 10-50 m were observed before FSP, fine carbides smaller than 20 m and martensitic matrix with fine grains were obtained after FSP. High hardness of over 900 HV, higher than the hardness in conventional D2 tool steel, was achieved under the condition of moderate rotational speed.

In biology, DNA is the central molecule that stores the genetic information. DNA also has attractive physicochemical features for use as materials in molecular assemblies. DNA is chemically stable and can be prepared in nearly any length and sequence by chemical and enzymatic syntheses. Auxiliary functional groups can be built into the backbone as amidite reagents using automated DNA synthesizers. In addition, we can choose an appropriate method from abundant chemistries for post-modifications. The structures of DNA complexes can be rationally designed by bottom-up self-assembly. Therefore, functional groups can be positioned on the DNA scaffold in distinct distance and spatial arrangements. In the last decade, a number of DNA-based allosteric molecular systems have been reported. Some of the systems function as signal transducers, amplifiers, and chemical catalysts. These systems are rather exciting as fundamental achievements of the studies for nanomachines or nanodevices. They should also be useful as robust molecular sensors for sensitive bioassays. In this review, we will cover the photochemically relevant DNA-based molecular systems. They are classified into three groups: (i) DNA-templated molecular/ion assemblies; (ii) DNA-directed complexation; and (iii) chemical transformations accelerated on DNA.

DNA-fiber EPR spectra revealed that intercalative binding of the ternary copper(II) complexes of cationic Schiff-bases and N-heteroaromatic amines induced the rearrangement of coordination spheres of the complexes from tetragonal pyramidal to square planar geometries. The binding of the complexes was also characterized by UV–vis, CD and fluorescence spectroscopy together with DFT calculation of the conformational change. The synergetic effect of the intercalation, the electrostatic interaction and the rearrangement of the coordination spheres enhanced the oxidative and the photodynamic DNA cleavage activities.

By inhibiting only two or three of 12 restriction enzymes, the series of [M(phen)(edda)] complexes [M(II) is Cu, Co, Zn; phen is 1,10-phenanthroline; edda is N,N'-ethylenediaminediacetate] exhibit DNA binding specificity. The Cu(II) and Zn(II) complexes could differentiate the palindromic sequences 5'-CATATG-3' and 5'-GTATAC-3', whereas the Co(II) analogue could not. This and other differences in their biological properties may arise from distinct differences in their octahedral structures. The complexes could inhibit topoisomerase I, stabilize or destabilize G-quadruplex, and lower the mitochondrial membrane potential of MCF7 breast cells. The pronounced stabilization of G-quadruplex by the Zn(II) complex may account for the additional ability of only the Zn(II) complex to induce cell cycle arrest in S phase. On the basis of the known action of anticancer compounds against the above-mentioned individual targets, we suggest the mode of action of the present complexes could involve multiple targets. Cytotoxicity studies with MCF10A and cisplatin-resistant MCF7 suggest that these complexes exhibit selectivity towards breast cancer cells over normal ones.

The thermal stability of the parallel motif triple helix DNA containing CG.CH+ base triplets is improved by silver ions. The N3 protons of cytosines on the third strand are replaced by the ions to ...