Itamar Willner

Hebrew University of Jerusalem, Yerushalayim, Jerusalem, Israel

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Publications (737)5389.07 Total impact

  • Chun-Hua Lu · Weiwei Guo · Yuwei Hu · Xiu-Juan Qi · Itamar Willner ·
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    ABSTRACT: Acrylamide-acrylamide nucleic acids are crosslinked by two cooperative functional motives to form shaped acrylamide-DNA hydrogels. One of the crosslinking motives responds to an external trigger leading to the dissociation of one of the stimuli responsive bridges, and to the transition of the stiff shaped hydrogels into soft shapeless states, where the residual bridging units, due to the chains entanglement, provide an intrinsic memory, for re-shaping of the hydrogels. Subjecting the shapeless states to counter stimuli restore the dissociated bridges, and regenerate the original shape of the hydrogels. By the cyclic dissociation and re-assembly of the stimuli-responsive bridges, the reversible switchable transitions of the hydrogels between stiff shaped hydrogel structures and soft shapeless states are demonstrated. Shaped hydrogels bridged by K(+)-stabilized G-quadruplexes/duplex units, by i-motif/duplex units or two different duplex bridges are described. The cyclic transitions of the hydrogels between shaped and shapeless states are stimulated in the presence of appropriate triggers and counter triggers (K(+)-ion/crown ether; pH = 5.0/8.0; fuel/anti-fuel strands). The shape memory hydrogels are integrated into shaped two-hydrogel or three-hydrogel hybrid structures. The cyclic programmed transitions of selective domains of the hybrid structures between shaped hydrogel and shapeless states are demonstrated. The possible applications of the shape memory hydrogels for sensing, inscription of information, and controlled release are discussed.
    Journal of the American Chemical Society 11/2015; DOI:10.1021/jacs.5b06510 · 12.11 Impact Factor
  • Ran Tel-Vered · Jason Kahn · Itamar Willner ·
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    ABSTRACT: Layered metal nanoparticle (NP) assemblies provide highly porous and conductive composites of unique electrical and optical (plasmonic) properties. Two methods to construct layered metal NP matrices are described, and these include the layer-by-layer deposition of NPs, or the electropolymerization of monolayer-functionalized NPs, specifically thioaniline-modified metal NPs. The layered NP composites are used as sensing matrices through the use of electrochemistry or surface plasmon resonance (SPR) as transduction signals. The crosslinking of the metal NP composites with molecular receptors, or the imprinting of molecular recognition sites into the electropolymerized NP matrices lead to selective and chiroselective sensing interfaces. Furthermore, the electrosynthesis of redox-active, imprinted, bis-aniline bridged Au NP composites yields electrochemically triggered "sponges" for the switchable uptake and release of electron-acceptor substrates, and results in conductive surfaces of electrochemically controlled wettability. Also, photosensitizer-relay-crosslinked Au NP composites, or electrochemically polymerized layered semiconductor quantum dot/metal NP matrices on electrodes, are demonstrated as functional nanostructures for photoelectrochemical applications.
    Small 10/2015; DOI:10.1002/smll.201501367 · 8.37 Impact Factor
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    ABSTRACT: A novel method to assemble acrylamide/acrydite DNA copolymer hydrogels on surfaces, specifically gold-coated surfaces, is introduced. The method involves the synthesis of two different copolymer chains consisting of hairpin A, HA, modified acrylamide copolymer and hairpin B, HB, acrylamide copolymer. In the presence of a nucleic acid promoter monolayer associated with the surface, the hybridization chain reaction between the two hairpin-modified polymer chains is initiated, giving rise to the cross-opening of hairpins HA and HB and the formation of a crosslinked hydrogel on the surface. The co-functionalization of the HA- and HB-modified polymer chains with G-rich DNA tethers, that include the G-quadruplex subunits, hydrogels of controlled and switchable stiffness are generated. In the presence of K(+)-ions, the hydrogel associated with the surface is cooperatively crosslinked by duplex units of HA and HB, and K(+)-ion-stabilized G-quadruplex units, giving rise to a stiff hydrogel. The 18-crown-ether-stimulated elimination of the K(+)-ions dissociates the bridging G-quadruplex units, resulting in a hydrogel of reduced stiffness. The duplex/G-quadruplex cooperatively-stabilized hydrogel associated with the surface reveals switchable electrocatalytic properties. The incorporation of hemin into the G-quadruplex units of the duplex/G-quadruplex cooperatively electrocatalyzes the reduction of H2O2. The 18-crown-6-ether stimulated dissociation of the hemin/G-quadruplex bridging units leads to a catalytically-inactive hydrogel.
    Nano Letters 10/2015; DOI:10.1021/acs.nanolett.5b04101 · 13.59 Impact Factor
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    ABSTRACT: Shape memory acrylamide/DNA hydrogels include two different crosslinkers as stabilizing elements. The triggered dissociation of one of the crosslinking elements transforms the shaped hydrogel into an arbitrarily shaped (or shapeless) quasi-liquid state. The remaining crosslinking element, present in the quasi-liquid, provides an internal memory that restores the original shaped hydrogel upon the stimulus-triggered regeneration of the second crosslinking element. Two pH-sensitive shape memory hydrogels, forming Hoogsten-type triplex DNA structures, are described. In one system, the shaped hydrogel is stabilized at pH = 7.0 by two different duplex crosslinkers, and the transition of the hydrogel into the shapeless quasi-liquid proceeds at pH = 5.0 by separating one of the crosslinking units into a protonated cytosine–guanine–cytosine (C–G·C+ ) triplex. The second shaped hydrogel is stabilized at pH = 7.0, by cooperative duplex and thymine–adenine–thymine triplex (T–A·T) bridges. At pH = 10.0, the triplex units separate, leading to the dissociation of the hydrogel into the quasi-liquid state. The cyclic, pH-stimulated transitions of the two systems between shaped hydrogels and shapeless states are demonstrated. Integrating the two hydrogels into a shaped “two-arrowhead” hybrid structure allows the pH-stimulated cyclic transitions of addressable domains of the hybrid between shaped and quasi-liquid states.
    Advanced Functional Materials 10/2015; DOI:10.1002/adfm.201503134 · 11.81 Impact Factor
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    ABSTRACT: The electropolymerization of thioaniline-modified Au nanoparticles (NPs) on thioaniline monolayer-functionalized electrodes in the presence of Zn(II)-protoporphyrin IX yields bis aniline-crosslinked Au NPs matrices that include molecular imprinted sites for binding the Zn(II)-protoporphyrin IX photosensitizer. The binding of the photosensitizer yields photoelectrochemically active electrodes that produce anodic photocurrents in the presence of the electron donor benzohydroquinone. The efficient photocurrents formed in the presence of the imprinted electrode are attributed to the high-affinity binding of the photosensitizer to the imprinted sites, Ka = 3.2 × 106 m−1, and to the effective transport of the photoejected electrons to the bulk electrode via the bridged Au NPs matrix. Similarly, a N,N′-dialkyl-4,4′-bipyridinium-modified Zn(II)-protoporphyrin IX photosensitizer-electron acceptor dyad is imprinted in the bis aniline-crosslinked Au NPs matrix. The photocurrent generated by the imprinted matrix is approximately twofold higher as compared to the photocurrent generated by the Zn(II)-protoporphyrin IX-imprinted Au NPs matrix. The efficient photocurrents generated in the presence of the bipyridinium-modified Zn(II)-protoporphyrin IX-imprinted matrix are attributed to the effective primary charge separation of the electron–hole species in the dyad structure, followed by the effective transport of the photoejected electrons to the electrode via the bis aniline-crosslinked Au NPs matrix.
    Advanced Functional Materials 09/2015; DOI:10.1002/adfm.201502801 · 11.81 Impact Factor
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    ABSTRACT: The synthesis, purification and structure characterization of a seven-ring interlocked DNA catenane is described. The design of the seven-ring catenane allows the dynamic reconfiguration of any of the four rings (R1, R3, R4, and R6) on the catenane scaffold, or the simultaneous switching of any combination of two, three or all four rings to yield sixteen different isomeric states of the catenane. The dynamic reconfiguration across the states is achieved by implementing the strand-displacement process in the presence of appropriate fuel/anti-fuel strands, and is probed by fluorescence spectroscopy. Each of the sixteen isomers of the catenane can be transformed into any of the other isomers, thus allowing for 240 dynamic transitions within the system.
    Nano Letters 09/2015; 15(10). DOI:10.1021/acs.nanolett.5b03280 · 13.59 Impact Factor
  • Chun‐Hua Lu · Itamar Willner ·
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    ABSTRACT: Stimuliresponsive DNA-funktionalisierte Nano- und Mikrocontainer, die aus mesoporösen SiO2-Nanopartikeln (SiO2-NPs), Mikrokapseln oder Micellen/Vesikeln bestehen, fungieren als Träger zur Freisetzung von Wirkstoffen. Die in den DNA-Sequenzen gespeicherte Information liefert den Code für die Ver- und Entriegelung der wirkstoffbeladenen Poren mesoporöser SiO2-NPs, für den Auf- und Abbau von Mikrokapseln oder Lipid-DNA-Micellen bzw. Lipid-DNA-Vesikeln und für den gezielten Transport von Nano- und Mikrocontainern zu Krebszellen. Es werden verschiedene Trigger eingesetzt, um die in den Nano- und Mikrocontainern enthaltenen Wirkstoffe durch Entriegelung der Poren der mesoporösen SiO2-NPs oder durch Abbau der Container freizusetzen. Hierzu gehören schaltbare DNA-Nanostrukturen (Nukleinsäure-Haarnadeln, i-Motive, G-Quadruplexe) und die Anwendung chemischer, thermischer oder photonischer Stimuli. Außerdem werden durch DNAzyme oder Enzyme stimulierte katalytische Prozesse genutzt, um die Wirkstoffe aus den Nano- und Mikrocontainern freizusetzen.
    Angewandte Chemie 08/2015; DOI:10.1002/ange.201503054
  • Chun‐Hua Lu · Itamar Willner ·
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    ABSTRACT: Stimuli-responsive DNA-functionalized nano- and microcontainers composed of mesoporous SiO2 nanoparticles (MP SiO2 NPs), microcapsules, or micelles/vesicles act as carriers for the transport and release of drugs. The information encoded in the DNA sequences provides instructive information for the gating of drug-loaded pores of MP SiO2 NPs, for the assembly and degradation of microcapsules or lipid-DNA micelles/vesicles, and for the targeting of nano-/microcontainers to cancer cells. Different triggers are applied to release the drugs loaded in the nano-/microcontainers by unlocking the pores of the MP SiO2 NPs or by degradation of the containers. These include the use of switchable DNA nanostructures (nucleic acid hairpins, i-motif, G-quadruplexes) and the implementation of chemical, thermal, or photonic stimuli. Also, catalytic processes stimulated by DNAzymes or enzymes are used to release drugs from the nano-/microcontainers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 08/2015; 54(42). DOI:10.1002/anie.201503054 · 11.26 Impact Factor
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    ABSTRACT: The synthesis of stimuli-responsive DNA microcapsules acting as carriers for different payloads, and being dissociated through the formation of aptamer-ligand complexes are described. Specifically, stimuli-responsive anti-adenosine triphosphate (ATP) aptamer-crosslinked DNA-stabilized microcapsules loaded with tetramethylrhodamine-modified dextran (TMR-D), CdSe/ZnS quantum dots (QDs) or microperoxidase-11 (MP-11), are presented. In the presence of ATP as trigger, the microcapsules are dissociated through the formation of aptamer-ATP complexes, resulting in the release of the respective loads. Selective unlocking of the capsules is demonstrated, and CTP, GTP or TTP do not unlock the pores. The ATP-triggered release of MP-11 from the microcapsules enables the MP-11 catalyzed oxidation of Amplex UltraRed by H2O2 to the fluorescent product resorufin.
    ACS Nano 08/2015; 9(9). DOI:10.1021/acsnano.5b03223 · 12.88 Impact Factor
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    Chun-Hua Lu · Weiwei Guo · Xiujuan Qi · Avner Neubauer · Yossi Paltiel · Itamar Willner ·
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    ABSTRACT: A G-rich nucleic acid tethered acrylamide/N-isopropylacrylamide (NIPAM) copolymer is prepared. The nucleic acid modified pNIPAM chains assemble, in the presence of K+ ions, into the stimuli-responsive G-quadruplex-crosslinked pNIPAM hydrogel undergoing cyclic and reversible solution/hydrogel/solid transitions. Addition of kryptofix [2.2.2] to the K+-stabilized G-quadruplex-crosslinked hydrogel eliminates the K+ ions from the crosslinking units resulting in the transition of the hydrogel into a pNIPAM solution. In turn, heating the pNIPAM hydrogel from 25˚C to 40˚C results in the transition of the hydrogel into a solid state, and cooling the solid to 25˚C restores the hydrogel state. Incorporation of hemin into the G-quadruplex-crosslinked hydrogel results in a catalytic hydrogel that catalyses the oxidation of aniline by H2O2 to form polyaniline. The polyaniline/pNIPAM hydrogel hybrid doped by 2M HCl forms the emeraldine salt, exhibiting electrical conductivity, 9 × 10-4 [cm•Ω]-1.
    Chemical Science 08/2015; 6(11). DOI:10.1039/C5SC02203G · 9.21 Impact Factor
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    ABSTRACT: We demonstrate the single-molecule imaging of the catalytic reaction of a Zn(2+) -dependent DNAzyme in a DNA origami nanostructure. The single-molecule catalytic activity of the DNAzyme was examined in the designed nanostructure, a DNA frame. The DNAzyme and a substrate strand attached to two supported dsDNA molecules were assembled in the DNA frame in two different configurations. The reaction was monitored by observing the configurational changes of the incorporated DNA strands in the DNA frame. This configurational changes were clearly observed in accordance with the progress of the reaction. The separation processes of the dsDNA molecules, as induced by the cleavage by the DNAzyme, were directly visualized by high-speed atomic force microscopy (AFM). This nanostructure-based AFM imaging technique is suitable for the monitoring of various chemical and biochemical catalytic reactions at the single-molecule level. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 07/2015; 54(36). DOI:10.1002/anie.201504656 · 11.26 Impact Factor
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    ABSTRACT: A new method to incorporate metal nanoparticles, NPs, into pores of mesoporous carbon nanoparticles, MPC NPs, is presented. MPC NPs loaded with metal ion solutions are capped with protein units. The electrochemical reduction of the pore-entrapped ions, followed by digestion of the protein caps, yields metal NPs-loaded MPC NPs electrodes. Pt NPs/MPC NPs electrodes are used for the electrocatalyzed reduction of O2 or H2O2. Furthermore, the metal NPs electrically contact enzymes with the bulk electrodes, as demonstrated for glucose oxidase-capped Pt NPs/MPC NPs electrodes that electrocatalyze glucose oxidation, and for horseradish peroxidase-capped Au NPs/MPC NPs electrodes, which electrocatalyze H2O2 reduction.
    Electroanalysis 07/2015; 27(9). DOI:10.1002/elan.201500183 · 2.14 Impact Factor
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    ABSTRACT: This chapter focuses on the structure and stabilization of triplex DNA. The canonical DNA triplex structure is generally formed between an oligonucleotide and a homopurine– homopyrimidine duplex. The third strand (triplex-forming oligonucleotide (TFO)) binds in the major groove of the duplex and forms hydrogen bonds with the hydrogen bond donor and acceptor groups available on the major groove edge of the purine bases. According to where the TFO originates from, triplexes can be classified as intramolecular and intermolecular triplexes. The third strand in the triplex can also result from an exogenously applied molecule to form an intermolecular triplex structure. The pH of the solution is an essential parameter for the CGC+ triplet. Basic oligopeptides, another class of biologically relevant polycations, can stabilize triplex DNA. Cationic amino acid residues of basic peptides might bind to and neutralize phosphate groups of triple-helical nucleic acids. One important emerging field is the use of synthetic molecules to tune and modify the stability, functionality, and assembly of DNA-based structures. These molecules can be incorporated into the structures through one of two methods: covalent insertion or non-covalent interactions. Due to the ease of automated synthesis and the efficiency of coupling approaches, a plethora of synthetic modifications are available. Insertion of synthetic linkers has several direct effects on the DNA duplexes. Covalently inserting synthetic molecules into the DNA backbone introduces many unique properties for DNA assembly and represents a powerful tool towards controlling structure. For the purposes of guiding DNA assembly, groove binders and intercalators have interesting properties. The application of these properties to DNA self-assembly is discussed in this chapter. Intercalators and groove binders have demonstrated the ability to stabilize fully duplexed structures, modify assembly outcomes, increase yields, functionalize assemblies, and connect blunt-ended duplexes. Oligodeoxynucleotides are readily synthesized in automatic fashion in lengths of up to 100–50 nucleotides, and they form antiparallel duplex structures, based on the base-paring rules of Watson and Crick. Duplexes of DNA strands have a typical persistence length in aqueous buffer of over 100 base pairs. Shortly after the publication on assemblies of hybrids with dimers as DNA arms, Seeman and coworkers succeeded in crystallizing DNA folding motifs into lattices with designed crystal structure. In order to develop the next generation of hybrids, the authors sought a collaboration with theoreticians. Wolfgang Wenzel and coworkers took it upon themselves to develop a system for simulating the assembly of DNA hybrids, using a coarse-grained model. The strength of the association of the second-generation hybrids warranted a special approach for melting curves. Branched oligonucleotide hybrids with rigid cores will remain interesting only if they show their usefulness in practical applications. Controlled assembly of soft nanoparticles requires a recognition event to trigger the formation of a non-covalent assembly. A large number of soft nanoparticles are known, and among the most important class of natural soft nanoparticles are vesicles. Vesicles are lipid nanoparticles based on natural lipids and are of particular interest due to their occurrence in nature as intraor extracellular transport vehicles. However, soft nanoparticles based on lipid bilayers possess a universal mode for encoding surfaces by membrane anchoring of lipid modified DNA. In light of the technically demanding procedures for solid nanoparticles, non-covalent attachment of DNA to lipid bilayer surfaces becomes a very attractive technology. Incorporation of one or more lipid-membrane anchors into DNA leads to different sequence designs, which in general all allow assembly of liposomes. Ultraviolet spectroscopy in the presence of liposomes allows monitoring of DNA controlled assembly processes based on double or triple helix formation. This chapter provides a concise overview of the delicate relationship between biologically relevant metal ions or metal complexes and the two classes of naturally occurring functional RNAs: ribozymes or riboswitches. It first introduces the most important types of metal ion– RNA interactions, concentrating on the biologically most significant metal ions and discussing the various coordination modes and most frequent specific binding sites. The chapter then presents the world of both small and large ribozymes giving special attention to the influence of cations on the structure, folding, and function. It further explains how metal ions and metal complexes are involved in the correct structure formation and functioning of riboswitches. Riboswitches usually bind only a single metabolite to undergo the structural rearrangement required for gene regulation. The mgtA and the M-box riboswitches are well-defined examples of metal-sensing RNA. A major research area in DNA nanotechnology involves the development of DNA switching systems and DNA machines. This chapter exemplifies several principles to assemble DNA switching devices and DNA machines and discusses the potential applications. It highlights the existing structural and functional “tool-boxes” of nucleic acids to assemble DNA switches and machines. The chapter explains the perspectives of the area within the broad topic of DNA nanotechnology. It exemplifies the tailoring of DNA switches by ions or physical triggers such as photonic or electrical signals. The use of DNA switches and machines in nano-medicine has sparked substantial interest and several preliminary reports highlighting the future potential of such systems. The dynamic and switchable control of the organization of plasmonic particles or fluorophore–plasmonicnanoparticle conjugates holds great promise in material science. DNA switches and machines are expected to provide effective scaffolds for programmed synthesis by the dictated stimuli-triggered interactions of chemical reactants. This chapter describes the use of DNA as chiral bio-scaffold in the design of hybrid catalysts and their application in asymmetric catalysis. Some current and relevant examples are discussed, followed by an overview of mechanistic studies. DNA-based asymmetric catalysis is an exponent of the general concept of hybrid catalysts, which aims to merge the attractive properties of homogeneous and bio-catalysis. There are two main approaches to the anchoring of a transition metal complex to DNA. In covalent anchoring, the ligand for the metal is attached to the DNA via a chemical bond. A particularly attractive aspect of supramolecular anchoring is the easy formation of the catalyst since it involves spontaneous self-assembly of the transition metal complex with DNA. Moreover, in this approach it is usually DNA from natural sources, such as calf thymus or salmon testes DNA, that is used.
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    ABSTRACT: DNAzyme-capped mesoporous SiO2 nanoparticles (MP SiO2 NPs) are applied as stimuli-responsive containers for programmed synthesis. Three types of MP SiO2 NPs are prepared by loading the NPs with Cy3-DBCO (DBCO=dibenzocyclooctyl), Cy5-N3, and Cy7-N3, and capping the NP containers with the Mg2+, Zn2+, and histidine-dependent DNAzyme sequences, respectively. In the presence of Mg2+ and Zn2+ ions as triggers, the respective DNAzyme-capped NPs are unlocked, leading to the “click” reaction product Cy3-Cy5. In turn, in the presence of Mg2+ ions and histidine as triggers the second set of DNAzyme-capped NPs is unlocked leading to the Cy3-Cy7 conjugated product. The unloading of the respective NPs and the time-dependent formation of the products are followed by fluorescence spectroscopy (FRET). A detailed kinetic model for the formation of the different products is formulated and it correlates nicely with the experimental results.
    Angewandte Chemie 05/2015; 127(40). DOI:10.1002/ange.201501777
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    ABSTRACT: DNAzyme-capped mesoporous SiO2 nanoparticles (MP SiO2 NPs) are applied as stimuli-responsive containers for programmed synthesis. Three types of MP SiO2 NPs are prepared by loading the NPs with Cy3-DBCO (DBCO=dibenzocyclooctyl), Cy5-N3 , and Cy7-N3 , and capping the NP containers with the Mg(2+) , Zn(2+) , and histidine-dependent DNAzyme sequences, respectively. In the presence of Mg(2+) and Zn(2+) ions as triggers, the respective DNAzyme-capped NPs are unlocked, leading to the "click" reaction product Cy3-Cy5. In turn, in the presence of Mg(2+) ions and histidine as triggers the second set of DNAzyme-capped NPs is unlocked leading to the Cy3-Cy7 conjugated product. The unloading of the respective NPs and the time-dependent formation of the products are followed by fluorescence spectroscopy (FRET). A detailed kinetic model for the formation of the different products is formulated and it correlates nicely with the experimental results. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 05/2015; 54(40). DOI:10.1002/anie.201501777 · 11.26 Impact Factor
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    ABSTRACT: The stabilization of G-quadruplexes by means of K+ ions, and the separation of the nanostructures by 18-crown-6 or [2.2.2] cryptand, provide means to assemble switchable photonic or electrocatalytic molecular systems. On page 3654, this is exemplified with the construction of a G-quadruplex-based photonic "DNA spring" by I. Willner and co-workers, and by the assembly of a switchable hemin/G-quadruplex nanostructure on an electrode, acting as an electrocatalytic "ON"/"OFF" switch towards the reduction of H2 O2 . Image designed by Guoyuan Tan. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Small 04/2015; 11(30). DOI:10.1002/smll.201403794 · 8.37 Impact Factor
  • H Bauke Albada · Eyal Golub · Itamar Willner ·
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    ABSTRACT: The binding properties of sequence-specific nucleic acids (aptamers) to low-molecular-weight ligands, macromolecules and even cells attract substantial scientific interest. These ligand-DNA complexes found different applications for sensing, nanomedicine, and DNA nanotechnology. Structural information on the aptamer-ligand complexes is, however, scarce, even though it would open-up the possibilities to design novel features in the complexes. In the present study we apply molecular docking simulations to probe the features of an experimentally documented L-argininamide aptamer complex. The docking simulations were performed using AutoDock 4.0 and YASARA Structure software, a well-suited program for following intermolecular interactions and structures of biomolecules, including DNA. We explored the binding features of a DNA aptamer to L-argininamide and to a series of arginine derivatives or arginine-like ligands. We find that the best docking results are obtained after an energy-minimization of the parent ligand-aptamer complexes. The calculated binding energies of all mono-substituted guanidine-containing ligands show a good correlation with the experimentally determined binding constants. The results provide valuable guidelines for the application of docking simulations for the prediction of aptamer-ligand structures, and for the design of novel features of ligand-aptamer complexes.
    Journal of Computer-Aided Molecular Design 04/2015; 29(7). DOI:10.1007/s10822-015-9844-5 · 2.99 Impact Factor
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    ABSTRACT: The design of artificial cells, mimicking functions of native cellular cells, is a continuous scientific goal. The development of stimuli-responsive chemical systems that stimulate cascaded catalytic transformations, trigger chemical networks, and control vectorial branched transformation and dose-controlled processes, provides minimal elements for mimicking cell functions. We report on the electrochemical addressing of electrodes that results in the programmed release of ions that trigger selective DNAzyme-driven chemical reactions, cascaded reactions that self-assemble catalytic DNAzyme polymers, and the ON-OFF switching and dose-controlled operation of the catalytic reactions. The addressable and potential-controlled release of Pb2+ or Ag+ ions into an electrolyte that includes a mixture of nucleic acids results in the metal ion-guided selection of nucleic acids that yield the formation of dictated DNAzymes stimulating orthogonal reactions or activating DNAzyme cascades.
    Chemical Science 04/2015; 6(6). DOI:10.1039/C5SC00744E · 9.21 Impact Factor
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    ABSTRACT: The capping of electron relay units in mesoporous carbon nanoparticles (MPC NPs) by crosslinking of different enzymes on MPC NPs matrices leads to integrated electrically contacted bienzyme electrodes acting as dual biosensors or as functional bienzyme anodes and cathodes for biofuel cells. The capping of ferrocene methanol and methylene blue in MPC NPs by the crosslinking of glucose oxidase (GOx) and horseradish peroxidase (HRP) yields a functional sensing electrode for both glucose and H2O2, which also acts as a bienzyme cascaded system for the indirect detection of glucose. A MPC NP matrix, loaded with ferrocene methanol and capped by GOx/lactate oxidase (LOx), is implemented for the oxidation and detection of both glucose and lactate. Similarly, MPC NPs, loaded with 2,2′-azino-bis(3-ethylbenzo­thiazoline-6-sulphonic acid), are capped with bilirubin oxidase (BOD) and catalase (Cat), to yield a bienzyme O2 reduction cathode. A biofuel cell that uses the bienzyme GOx/LOx anode and the BOD/Cat cathode, glucose and/or lactate as fuels, and O2 and/or H2O2 as oxidizers is assembled, revealing a power efficiency of ≈90 μW cm−2 in the presence of the two fuels. The study demonstrates that multienzyme MPC NP electrodes may improve the performance of biofuel cells by oxidizing mixtures of fuels in biomass.
    Advanced Energy Materials 04/2015; 5(8). DOI:10.1002/aenm.201401853 · 16.15 Impact Factor

Publication Stats

42k Citations
5,389.07 Total Impact Points


  • 1977-2015
    • Hebrew University of Jerusalem
      • • Institute of Chemistry
      • • Farkas Center for Light-Induced Processes
      • • Department of Organic Chemistry
      • • Fritz Haber Center for Molecular Dynamics Research
      Yerushalayim, Jerusalem, Israel
  • 2008
    • University of Bologna
      Bologna, Emilia-Romagna, Italy
  • 2007
    • Universität Siegen
      Siegen, North Rhine-Westphalia, Germany
  • 1992
    • National Renewable Energy Laboratory
      گلدن، کلرادو, Colorado, United States
  • 1979-1980
    • Ben-Gurion University of the Negev
      • Department of Chemistry
      Be'er Sheva`, Southern District, Israel