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[Display omitted] • A novel method of waste plastics conversion to a matrix for metal NPs was proposed. • Waste PET was converted to a hydrogel matrix for the synthesis of Au and Ag NPs. • Hydrogel plays a dual role of reductant and matrix for Au or Ag NPs growth. • Application of the hybrid hydrogel as a catalyst was demonstrated. • Hybrid hydrogel with NPs shows high reusability after four catalytic reactions. The progressive accumulation of discarded plastic in the environment demands further development of waste management of plastic waste and conversion technologies of such waste to value-added materials. Recently, the conversion of plastic waste to functional materials via chemical recycling has attracted considerable attention. In this report, plastic waste (PET) was utilized for the preparation of a hydrogel-based catalyst via a cross-linking reaction of PET-derived oligo(terephthalamide)s followed by the electroless metallization. The polymeric matrix of PET-derived hydrogel plays multiple roles of (i) an adsorption media for noble metal ions such as Au3+ and Ag+, (ii) a reducing agent of Au3+ and Ag+ ions to Au0 and Ag0, and (iii) a matrix for the controlled growth of Au and Ag nanoparticles (AuNPs and AgNPs). The obtained hybrid hydrogels after metallization contained well-dispersed AuNPs and AgNPs of 6.1 ± 3.7 nm or 6.1 ± 1.4 nm size, respectively. The catalytic activities of the hybrid hydrogels with metal nanoparticles were studied in a model system of p -nitrophenol reduction in an aqueous solution. The hybrid materials of both Au@hydrogel and Ag@hydrogel were catalytically active for the reduction of p -nitrophenol, obeying the first-order kinetics. Importantly, the AuNPs or AgNPs in the hydrogel matrix preserved the original catalytic activity after multiple p -nitrophenol reduction reactions, showing a promising reusability of the catalysts. The proposed here approach aims to broaden the scope of conversion routes of plastic waste to value-added materials as well as to develop new types of polymeric matrices for templating and growth of metal nanoparticles for catalytic applications. [ABSTRACT FROM AUTHOR]

Large topologically associated domains (TADs) contain irregularly spaced nucleosome clutches, and interactions between such clutches are thought to aid the compaction of these domains. Here, we reconstituted TAD-sized chromatin fibers containing hundreds of nucleosomes on native source human and lambda-phage DNA and compared their mechanical properties at the single-molecule level with shorter '601' arrays with various nucleosome repeat lengths. Fluorescent imaging showed increased compaction upon saturation of the DNA with histones and increasing magnesium concentration. Nucleosome clusters and their structural fluctuations were visualized in confined nanochannels. Force spectroscopy revealed not only similar mechanical properties of the TAD-sized fibers as shorter fibers but also large rupture events, consistent with breaking the interactions between distant clutches of nucleosomes. Though the arrays of native human DNA, lambda-phage and '601' DNA featured minor differences in reconstitution yield and nucleosome stability, the fibers' global structural and mechanical properties were similar, including the interactions between nucleosome clutches. These single-molecule experiments quantify the mechanical forces that stabilize large TAD-sized chromatin domains consisting of disordered, dynamically interacting nucleosome clutches and their effect on the condensation of large chromatin domains. [ABSTRACT FROM AUTHOR]

Accumulation of mismanaged plastic in the environment and the appearance of emerging plastic-derived pollutants such as microplastics strongly demand technologies for waste plastic utilization. In this study, polyethylene terephthalate (PET) from waste plastic bottles was directly utilized to prepare a matrix of an adsorbent for cesium (Cs+) removal. The organic matrix of PET-derived oligomers obtained by aminolysis depolymerization was impregnated with bentonite clay and magnetite nanoparticles (Fe 3 O 4 NPs), playing the roles as a major adsorptive medium for Cs+ removal and as a functional component to primarily provide efficient separation of the hybrid adsorbent from aqueous system, respectively. The obtained hybrid composite microparticles were next tested as an adsorbent for the removal of Cs+ cation from aqueous solutions. The adsorption process was characterized by fast kinetics reaching ca. 60% of the equilibrium adsorption capacity within 5 min and the maximum adsorption capacity toward Cs+ was found to be 26.8 mg/g. The adsorption process was primarily dominated by the cationic exchange in bentonite, which was not significantly affected by the admixture of the competing mono- and divalent cations (Na+, K+, and Mg2+). The proposed approach here exploits the sustainable utilization scenario of plastic waste-derived material to template complex multifunctional nanocomposites that can find applications for pollution cleaning and environmental remediation. [Display omitted] • A novel method of waste PET conversion to a matrix for bentonite was proposed. • Microparticles were prepared by PET aminolysis and co-precipitation with bentonite. • Fe 3 O 4 NPs were utilized to confer the hybrid microparticles with magnetic property. • Application of hybrid magnetic microparticles for cesium removal was demonstrated. • Adsorption capacity of hybrid magnetic microparticles for cesium was ca. 26.8 mg/g. [ABSTRACT FROM AUTHOR]

Polymer matrices are important host materials for nesting nanoparticles to be used in photonic, catalytic, environmental, and other applications. Several past studies suggested a unique role of DNA macromolecular template in the process of noble metal nanoparticle (NP) formation and growth; yet, no comparative studies with other polymeric matrices were performed. In order to address the effect of DNA on metal NP formation and catalytic performance, we synthesized Au NP in PSSNa/PAH/DNA multilayered films containing varied amounts of DNA and systematically studied morphology of multilayers, structure of gold NP formed in the multilayers, and catalytic properties of the NP. We found that decrease of Au NP size due to increase of DNA contents in the multilayers caused significant enhancement in the hybrid material catalytic properties. Graphical abstract [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is a mass-produced plastic material widely used for the manufacturing of bottles, textile fibers, and other products. The mismanaged plastic problem and the associated environmental pollution urge the development of waste plastic utilization methods based on mechanical, chemical, and energy recycling. Basic technologic processes of PET chemical recycling, that have been established decades ago, were substantially extended by recent efforts of chemists and chemical engineers toward new materials based on PET-derived traditional as well as novel chemical feedstocks. This review summarizes and systematizes reported approaches and recycling protocols for waste PET conversion into functional materials based on PET-derived chemical feedstocks and gives an overview of their application fields. [Display omitted] • Recent progress in the conversion of waste PET to functional materials is reviewed. • New waste PET-derived chemical feedstocks support versatile materials design. • PET-derived materials target construction, coatings, adsorbents, catalysis, and energy sectors. • PET-derived alternatives hold increasing promise for substituting of oil-based raw chemicals. [ABSTRACT FROM AUTHOR]

In a living cell, long genomic DNA is strongly compacted and exists in the environment characterized by a dense macromolecular crowding, high concentrations of mono- and divalent cations, and confinement of ca. 10 μm size surrounded by a phospholipid membrane. Experimental modelling of such complex biological system is challenging but important to understand spatiotemporal dynamics and functions of the DNA in cell. The accumulated knowledge about DNA condensation/compaction in conditions resembling those in the real cell can be eventually used to design and construct partly functional “artificial cells” having potential applications in drug delivery systems, gene therapy, and production of synthetic cells. In this review, I would like to overview the past progress in our understanding of the DNA conformational behavior and, in particular, DNA condensation/compaction phenomenon and its relation to the DNA biological activity. This understanding was gained by designing relevant experimental models mimicking DNA behavior in the environment of living cell. Starting with a brief summary of classic experimental systems to study DNA condensation/compaction, in later parts, I highlight recent experimental methodologies to address the effects of macromolecular crowding and nanoscale and microscale confinements on DNA conformation dynamics. All the studies are discussed in the light of their relevance to DNA behavior in living cells, and future prospects of the field are outlined. [ABSTRACT FROM AUTHOR]

DNA hydrogel was used as a 'reactor' to synthesize gold nanoparticles of various sizes. By varying the amount of reducing agent in the reaction between HAuCl4 and NaBH4 in hydrogel it was possible to vary the average size of gold nanoparticles between 2 and 6 nm. Catalytic activity of DNA hybrid hydrogels with embedded gold nanoparticles of various sizes in hydrogenation reaction of nitroaromatic compound was compared and shown to have the maximum values at average size of gold NP ca. 4 nm. [ABSTRACT FROM AUTHOR]

Hypothesis By incorporating catalytically active nanoparticles into polymeric hydrogel one can tune the catalytic activity of such a hybrid material by affecting the state of polymer matrix. Experiment Herein, hybrid hydrogel was prepared by metallization of DNA cross-liked hydrogel via absorption of gold precursor and reduction by NaBH 4 , and its catalytic activity under various swelling ratio was studied spectroscopically. Findings Catalytic activity of Au nanoparticles in hydrogel was shown to depend drastically on a swelling degree of hydrogel easily controlled by a change in an ionic strength of solution. Increase of the catalytic reaction rate was proportional to the volume of hybrid hydrogel indicating that diffusion of reactants toward catalytic centers inside hydrogel is crucial for the efficient catalysis by soft-matter-based hybrid material. [ABSTRACT FROM AUTHOR]

A great number of past in vivo and in vitro studies on DNA condensation/compaction made clear DNA conformational behavior and its influence on DNA bioactivity in systems containing either polymers or colloids which are positively charged or electrically neutral. However, there still remains a lack of understanding about interaction between DNA and like-charged species. Such knowledge is important for deeper insight into DNA behavior in cellular environment, where DNA encounters negatively charged biopolymers such as RNA and RNase at relatively high concentrations, and should contribute to an overall understanding of the intrinsic mechanism that underlies the spatiotemporal dynamics of biomacromolecules in various cellular processes. In this review, we focus on DNA condensation/compaction by negatively-charged species, compare it with established earlier model systems of DNA condensation/compaction, and discuss recent advances in the field. We show that DNA compaction by negatively charged polymers and colloids exhibits some similarities with that induced by neutral polymers, but stress that several new features imposed by the electrostatics of polyanions should be considered to grasp the whole picture. [ABSTRACT FROM AUTHOR]

Well-dispersed uniform gold nanorings of 100nm size were fabricated by slow photochemical reduction of aqueous gold(III) on compacted DNA of toroidal morphology, along with deposition of a thin gold layer on DNA condensates. The outer and inner diameters of nanorings were 105±17nm and 26±14nm, respectively. [ABSTRACT FROM AUTHOR]

Upto the present, DNA structural transitions caused by cationicpolymers as well as in concentrated solutions of neutral polymersare well documented, while a little is known about DNA interactionwith like-charge species. Herein, changes in the structure of DNAinduced by anionic nanoparticles of different sizes (20–130nm) were investigated by combining single-molecule DNA fluorescentmicroscopy, to monitor the conformational dynamics of long-chain DNA,with spectroscopic methods, to gain insight into changes in the secondarystructure of DNA. The results showed that several percent of negativelycharged silica nanoparticles induced DNA compaction from a coil toa globule, and this change was accompanied by a decrease in the meltingtemperature of the DNA double helix. DNA was compacted into toroidalcondensates with reduced diameters of about 20–30 nm. Smaller20 nm nanoparticles triggered a DNA coil–globule transitionat lower concentrations, but the exclusion volume for each type ofnanoparticle at the point of complete DNA collapse, as estimated bytaking into account the depth of the ionic atmosphere, was found tobe almost the same. [ABSTRACT FROM AUTHOR]

Treasure trove: A method for the extraction of noble and rare‐earth metals by a DNA cross‐linked hydrogel, based on high DNA affinity to these elements, is described (see picture). The hydrogel is promising in applications for metal accumulation and recycling. [ABSTRACT FROM AUTHOR]

We report a protocol for entrapping of various water-dispersed nanomaterials: fullerenes, multiwall carbon nanotubes, quantum dots (semiconductor nanoparticles), and gold nanorods, into a DNA-chitosan complex. In contrast to small-size nanomaterial particles, the bulky DNA-chitosan interpolyelectrolyte complex incorporating the dispersed dispersed nanomaterials complexation with poiycation and polyanion nanomaterials can be easily separated from aqueous media by centrifugation, filtration, or decantation. While the removal of nanoparticles by centrifugation is equally efficient for every type of nanoparticles and reaches 100%, the higher efficiency of the nanomaterials removal by other two methods larger size of nanoparticles. The application of this entrapping protocol for removal of nanomaterials from water is favored by is discussed. [ABSTRACT FROM AUTHOR]

The formation of metal-containing Ag-mercaptoethanol (−Ag-S(R)−)n complexes on DNA chain scaffold was studied by UV spectroscopy, zeta potential measurement, and fluorescence and transmission electron microscopies. Experimental results made clear the mechanism of DNA mineralization and compaction, according to which intercalation of silver cations into DNA scaffold and further formation of (−Ag-S(R)−)n oligomeric complexes on DNA induce efficient DNA chain compaction by terminal Ag+ cations. By transmission electron microscopy the formation of fiber-like DNA-templated nanostructures was observed. DNA-Ag-thiol complexes are promising for DNA-templated engineering of hybrid 1D nanostructures with adjustable chemical functionalities by choosing appropriate thiol ligand. [ABSTRACT FROM AUTHOR]

The effects of anionic and cationic nanoparticles (15 and 100 nm in diameter) on the stability of the secondary structure of DNA were studied in DNA denaturation and renaturation processes. The results showed that DNA denaturation is greatly inhibited in the presence of cationic nanoparticles. In contrast, in the presence of even large amounts of anionic nanoparticles, the DNA melting transition occurs at the original melting temperature. The effects of the size and concentration of nanoparticles on DNA denaturation are discussed. [ABSTRACT FROM AUTHOR]

Fluorescence microscopy was used to study the folding transition of giant DNAs, T4 DNA (ca. 166 kbp), and A. DNA (ca. 48 kbp), which proceeds through intermediates with intramolecular segregation induced by pteridine-polyamine conjugates, i.e., 2-amino-6,7-dimethyl-4-(4,9,13-triazatridecylamino)pteridine and -4-(3-(aminopropyl)amino)pteridine. According to the results of DNA denaturation, UV and fluorescent spectroscopy, and transmission electron microscopic observations, it became clear that DNA folding induced by the polyamine derivative is not a continuous shrinking process but a combination of discontinuous processes. [ABSTRACT FROM AUTHOR]

The large accumulation and low recycling rates of polyolefin waste have posed a threat to the environment and human health. The shortage of chemical recycling methods for polyolefins strongly demands the development of new and sustainable treatment technologies for hydrocarbon plastics to improve their waste management. In this study, polyethylene (PE) and polypropylene (PP) were utilized for the preparation of multi-color polymer carbon dots (PCDs) via a two-step hydrothermal (HT) synthesis involving (i) thermo-oxidative degradation of polyolefins to precursors containing plentiful oxygen-based functional groups, and (ii) modification with phenylenediamine (PDA). The fluorescence of PCDs depends on the structure of isomeric PDA and PCDs modified by ortho -, meta -, and para -PDA emit blue, green, and yellow color fluorescence, respectively. The formation mechanism of PCDs, involving dehydrative condensation and amination of PE or PP-derived precursors by PDA, was proposed. The obtained PCDs were utilized for the detection and quantification of Fe3+ ions at ppm concentrations. The proposed strategy here aims to broaden the scope of the chemical recycling methods for polyolefin plastic waste as well as to develop a conversion route of polyolefin to value-added materials. [Display omitted] • PE or PP was converted to multi-color polymer carbon dots via two-step hydrothermal synthesis. • Hydrothermal decomposition of PE or PP in H 2 O 2 results in the formation of ca. 10 nm PCDs. • PCDs from PE or PP can be functionalized by hydrothermal reaction with phenylenediamines. • The fluorescence color of functionalized PCDs depends on the structure of phenylenediamines. • Fluorescent PCDs from PE and PP can be used for the detection of Fe3+ and Hg2+ in water. [ABSTRACT FROM AUTHOR]

The cover picture shows extraction of several valuable elements of the periodic table by DNA hydrogel, which is cut out in the form of a blossom from a Japanese cherry tree and stained with a pink DNA dye, ethidium bromide. In their Communication on page 619 ff., A. Zinchenko and co‐workers outline the application of DNA cross‐linked hydrogel for efficient extraction of noble and rare‐earth metals. They demonstrate that placement of DNA hydrogel into a solution containing AuIII, PdII, or YbIII for several hours yields, in a single step, up to 70% of the metals from the aqueous phase in the hydrogel matrix. [ABSTRACT FROM AUTHOR]

Focuses on controlling the intrachain segregation on a single DNA molecule. Distribution of the number of mini-globules on DNA individual chains after partial collapse by diammonium salts; Examples of transmission electron micrographs of intrachain segregated states.

Abstract Contamination of soil by engineered nanomaterials (ENM) is an emergent environmental problem that urges the development of robust treatment protocols to prevent ENM transport through soil. We developed a method for efficient entrapment and retention of ENM in solid porous media of quartz sand with grain size of 300–500 μm used as a simple model of soil and studied the transport properties of multi-walled carbon nanotubes, fullerenes, silica and gold nanoparticles through the sand-packed column by UV–vis and fluorescent spectroscopy. The treatment of ENM-contaminated porous media with a mixture of oppositely charged polyelectrolytes, cationic poly(diallyldimethylammonium chloride) and anionic poly(acrylic acid) sodium salt, dissolved in NaCl solution followed by dilution in the column results in strong electrostatic interaction between the polyelectrolytes and a formation of inter-polyelectrolyte complexes (IPEC) that induce flocculation of ENM and adsorption to the surface of sand. The method demonstrates excellent ENM entrapment efficiency (>90%) and high capacity of several grams of ENM per 1 g of polyelectrolytes. The IPEC network formed after the treatment also serves as an efficient protection barrier for newly added ENM contaminants. The method is universal for various types of ENM (carbon ENM, metal and oxide nanoparticles) and equally efficient for distilled water, tap water, or lake water eluents. Graphical abstract Image 1 Highlights • Transport of engineered nanomaterials in a porous media is efficiently inhibited by a treatment with polyelectrolytes. • A network of polyelectrolytes entraps nanomaterials immobilizing them on the surface of porous media. • Pre-treatment of a porous media with polyelectrolytes creates excellent barrier against ENM contamination. • The capacity of the method reaches several grams of entrapped nanomaterials per gram of polyelectrolytes. [ABSTRACT FROM AUTHOR]

Invited for this month's cover is the group of Prof. Shizuaki Murata and Dr. Anatoly Zinchenko from Nagoya University and the group of Prof. Vladimir Sergeyev from Moscow State University. The cover picture shows the accumulation of noble and rare-earth metals by DNA cross-linked hydrogel. Read the full text of the article on . [ABSTRACT FROM AUTHOR]

We have developed a novel system for photocontrol of the fusion of lipid vesicles through the use of a photosensitive surfactant containing an azobenzene moiety (AzoTAB). Real-time microscopic observations clarified a change in both the surface area and internal volume of vesicles during fusion. We also determined the optimal cholesterol concentrations and temperature for inducing fusion. The mechanism of fusion can be attributed to a change in membrane tension, which is caused by the solubilization of lipids through the isomerization of AzoTAB. We used a micropipet technique to estimate membrane tension and discuss the mechanism of fusion in terms of membrane elastic energy. The obtained results regarding this novel photoinduced fusion could lead to a better understanding of the mechanism of membrane fusion in living cells and may also see wider applications, such as in drug delivery and biomimetic material design. [ABSTRACT FROM AUTHOR]

Fluorescence microscopic observation of individual T4 DNA molecules revealed that the MukBEF complex (bacterial condensin) and its subunit, the MukB (a member of the SMC [structural maintenance of chromosomes] superfamily) homodimer, of Escherichia coli markedly shrunk large DNA molecules in the presence of hydrolyzable ATP. In contrast, in the presence of ADP or ATP-γS, the conformation of DNA was almost not changed. This suggests that the ATPase activity of subunit MukB is essential for shrinking large DNA molecules. Stretching experiments on the shrunken DNA molecules in the presence of ATP and MukBEF indicated a cross-bridging interaction between DNA molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chitin and chitosan hydrochars were prepared by hydrothermal and microwave treatments. • Adsorption capacities of hydrochars toward pharmaceuticals were compared. • The mechanism of pharmaceutical adsorption depended on the HT treatment temperature. • Alkaline activation of CS and CT biochars increases adsorption capacities by 5–40 %. Hydrothermal treatment of fishery waste-derived chitin (CT) and chitosan (CS) was performed to prepare hydrochar adsorbents for the removal of pharmaceuticals of environmental concern. By systematically studying the effect of treatment conditions on the biochar structure, the correlation between hydrochar properties and the adsorption capacities was clarified to optimize the adsorption performance. CS hydrochars obtained by lower-temperature treatment showed high adsorption capacities for the pharmaceuticals having carboxyl groups attributed to the electrostatic binding. A decrease in the density of available amines in CS hydrochars prepared at higher temperatures resulted in lower adsorption capacities and the manifestation of different adsorption mechanisms based on hydrophobic and π-π interactions. CT hydrochars showed lower adsorption capacities than CS hydrochars due to inefficient carbonization and lack of adsorption sites. The hydrochar adsorbents prepared in this study address simultaneously the problems of marine waste bioresource utilization and environmental cleaning from the emergent pollutants. [ABSTRACT FROM AUTHOR]

Hypothesis Although the interaction of DNA with various types of intercalating chemicals, such as planar polycyclic aromatic compounds, has been extensively investigated over the past several decades, little is known about the relationship between the structure of a DNA binder and its affinity for DNA. The use of DNA as an adsorbent for environmental cleaning purposes requires information on its affinity for organic chemicals with different structures. Experiment In the present study we investigated the binding of DNA to aromatic chemicals with various structures and charges by three methods: binding of organic chemicals to DNA followed by removal by precipitation with cationic nanoparticles (1) or a cationic surfactant (2), and absorption of organic chemicals by a DNA hydrogel (3). Findings The results showed that, for most neutral organic chemicals, the hydrophobicity of the organic molecule is the main driving force for efficient binding to DNA. The double-helicity of DNA contributed to stronger binding to most of the compounds. The efficiency of the uptake of organic chemicals increased substantially when a hydrophobic cationic surfactant was used for DNA-complex condensation and removal. The potential environmental application of DNA as an adsorbent for the removal of aromatic organic pollutants from water is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Mercury is well known to be harmful for environment and for humans; therefore purification from heavy metal ions and, in particular, mercury pollutions is presently an important research direction of environmental science. In this report we propose a method for mercury removal from aqueous solutions, which is based on a high affinity of mercury ion to nucleic acids and formation of polymer–colloidal complexes between DNA–Hg complex and cationic surfactant. It is demonstrated that using this two-step mercury removal procedure one can remove over 95% of mercury contents from solutions in a broad range of mercury concentrations and solution pHs. [Copyright &y& Elsevier]

We report an electrochemical approach to extract methanol from lignin with a maximum efficiency of 95% under mild conditions of ambient pressure and a temperature of 75 °C. Hydroxyl radicals were generated from water over a platinum-sputtered anode and attacked the syringyl and guaiacyl units of the lignin. Methoxy groups in the units were demethylated to methanol with a yield greater than 40% through the formation of hemiketal intermediates. The electro-oxidation was coupled to cathode reactions that generated hydrogen in a helium flow and electric power in an air flow. Another important aspect of this approach is that no extra energy or effort was required to separate methanol from the reaction system. This technology can accelerate the replacement of fossil organic resources with renewable biomass resources. [Display omitted] • Lignin is anodically demethylated to methanol under mild conditions. • The faradaic efficiency for methanol formation reaches 95%. • Methanol yields of over 40% are obtained irrespective of the lignin weight. • Hydroxyl radicals function as a reaction initiator for demethylation. • The anode reaction proceeds in both electrolysis and fuel-cell modes. [ABSTRACT FROM AUTHOR]

Reduction of tetrachloroaurate( iii ) ions in solutions of native DNA results in a formation of either small gold nanoparticles or continuous nanowires decorating DNA macromolecular template. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The magnetic bentonite-chitosan beads were synthesized as adsorbent for Cs+ removal. • The porous adsorbent functioned by the synergistic effect of bentonite and chitosan. • Bentonite-chitosan beads capture Cs+ selectively in presence of the co-existing cations. • Adsorbent was recycled by 0.1 mol L−1 of Mg2+ for quantitative desorption of Cs+ from beads. Abstract Easy-to-obtain magnetic bentonite-chitosan hybrid beads (Bn-CTS) were prepared by immobilizing bentonite within a porous structure of chitosan beads to achieve a hybrid adsorption effect for the removal of cesium ion (Cs+) from water. The hybrid adsorbent, which had a porous structure and abundant binding sites contributed by both chitosan and bentonite, ensured superb adsorption characteristics. The paramagnetic character of the beads enabled their facile separation for recycling. The chitosan/bentonite ratio, pH and contact time were optimized to achieve the optimal Cs+ efficiency, and the adsorption kinetics and isotherms were thoroughly discussed. The adsorption kinetics obeyed the pseudo-second-order model, and the best fitted equation for equilibrium data was the Langmuir isotherm model. The maximum adsorption capacity of the bentonite-chitosan beads was 57.1 mg g−1. The adsorbent had excellent selectivity towards Cs+ adsorption in the presence of abundant cations (Li+, Na+, K+ and Mg2+). The adsorbent was able to be recycled by treating the beads with 0.1 mol L−1 of MgCl 2 to quantitatively desorb Cs+ from the beads. Overall, the magnetic bentonite-chitosan beads can be used as a highly efficient adsorbent for radioactive waste disposal and management. [ABSTRACT FROM AUTHOR]

Highly ordered, multi-layered, regular hexagonally patterned and size controlled honeycomb magnetic chitosan hydrogel beads were successfully fabricated by a facile method combining breath-figure templating and co-precipitation processing. The chitosan honeycomb beads were characterized and the unique structure formation mechanism was outlined. The diameter of pores in the hexagonally patterned structure was ∼10 μm, and the saturation magnetization of the chitosan honeycomb containing Fe 3 O 4 nanoparticles ( ca. 5 ± 2 nm) was around 12 emu/g. [ABSTRACT FROM AUTHOR]

The substrate specificity of recombinant full-length diguanylate cyclase (DGC) of Thermotoga maritima with mutant allosteric site was investigated. It has been originally shown that the enzyme could use GTP closest analogues – 2′-deoxyguanosine-5′-triphosphate (dGTP) and 9-β-D-arabinofuranosyl-guanine-5′-triphosphate (araGTP) as the substrates. The first demonstrations of an enzymatic synthesis of bis-(3′-5′)-cyclic dimeric deoxyguanosine monophosphate (c-di-dGMP) and the previously unknown bis-(3′-5′)-cyclic dimeric araguanosine monophosphate (c-di-araGMP) using DGC of T. maritima in the form of inclusion bodies have been provided. [ABSTRACT FROM PUBLISHER]

Abstract: The protective effects of alkali metal ions (Li+, Na+, K+, Rb+ and Cs+) against spermidine-induced DNA compaction were studied using single-molecule observations. We found that all alkali metal salts prevent DNA compaction, where Na+ more strongly prevented DNA compaction than other alkali metal ions. We discuss our results in terms of changes in ionic radii in relation to the net translational entropy of small ions due to ionic exchange between trivalent and monovalent cations. [Copyright &y& Elsevier]

Ascorbic acid is often regarded as an antioxidant in vivo , where it protects against cancer by scavenging DNA-damaging reactive oxygen species. However, the detailed mechanism of the action of ascorbic acid on genetic DNA is still unclear. We examined the effect of ascorbic acid on the higher-order structure of DNA through real-time observation by fluorescence microscopy. We found that ascorbic acid generates a pearling structure in single giant DNA molecules, with elongated and compact regions coexisting along a molecular chain. Results from electron microscopy and atomic force microscopy indicate that the compact regions assume a loosely packed conformation. A possible mechanism for the induction of this conformational change is discussed in relation to the interplay between the higher-order and second-order structures of DNA. [ABSTRACT FROM AUTHOR]

Investigates the secondary structure of DNA by cross-linked cationic hydrogel. Interaction of DNA with polycations; Influence of DNA secondary structure on sorption of DNA polyanions; Reaction mechanism between DNA and dimethylammonium chloride.

Ubiquitous on Earth, DNA and other nucleic acids are being increasingly considered as promising biomass resources. Due to their unique chemical structure, which is different from that of more common carbohydrate biomass polymers, materials based on nucleic acids may exhibit new, attractive characteristics. In this study, fluorescent nanoparticles (biodots) were prepared by a hydrothermal (HT) method from various nucleic acids (DNA, RNA, nucleotides, and nucleosides) to establish the relationship between the structure of precursors and fluorescent properties of biodots and to optimize conditions for preparation of the most fluorescent product. HT treatment of nucleic acids results in decomposition of sugar moieties and depurination/depyrimidation of nucleobases, while their consequent condensation and polymerization gives fluorescent nanoparticles. Fluorescent properties of DNA and RNA biodots are drastically different from biodots synthesized from individual nucleotides. In particular, biodots synthesized from purine-containing nucleotides or nucleosides show up to 50-fold higher fluorescence compared to analogous pyrimidine-derived biodots. The polymeric nature of a precursor disfavors formation of a bright fluorescent product. The reported effect of the structure of the nucleic acid precursor on the fluorescence properties of biodots should help designing and synthesizing brighter fluorescent nanomaterials with broader specification for bioimaging, sensing, and other applications. [ABSTRACT FROM AUTHOR]