Search

Abstract: Chemical surface modification of neuron-surface interfaces is essential for the development of biologically active and functional neural interfaces. Different types of surface modification schemes are required to derivatize either electrode or insulator surfaces, which limits the surface chemistry based neural interface design. Herein, we report a novel and powerful approach for modifying neuron-surface interfaces using mussel-inspired polymer (‘polydopamine film(polyDA)’) for generating effective chemical platforms on both electrode and insulator surfaces simultaneously. We applied polyDAs to common neural interface surfaces (gold, glass, platinum, indium tin oxide, liquid crystal polymer) and subsequently functionalized them by covalently linking biomolecules. The surfaces coated with polyDAs exhibited uniform and reproducible surface properties and they all became neuron-adhesive after linking with poly-d-lysine. In addition, polydopamine-coated microelectrode arrays were readily functional such that spontaneous and evoked neural activities could be recorded from cultured neuronal networks. We have successfully showed that a novel polyDA can be effectively used for the neural interface design. [Copyright &y& Elsevier]

Back and forth: Enzymatic, reversible polymerization on gold surfaces was efficiently carried out from surface ‐ tethered self ‐ priming oligodeoxynucleotides in a sequence ‐ specific fashion by using two kinds of enzymes. Taq DNA polymerase, acting as a catalyst, facilitated DNA polymerization, and DNA restriction enzymes cut DNA polymers from the surface. [ABSTRACT FROM AUTHOR]

Herein we demonstrate a systematic investigation of chemically functionalizable, non-biofouling agarose films over large-area glass surfaces. Agarose films, prepared with various concentrations of aqueous agarose, were activated by using periodate oxidation to generate aldehyde groups at the termini of the agarose chains. The non-biofouling efficacy and binding capabilities of the activated films were evaluated by using protein and cellular patterning, performed by using a microarrayer, microcontact printing, and micromolding in capillaries. Characterization by using a fluorescence slide scanner and a scanning-probe microscope revealed that the pore sizes of the agarose films played an important role in achieving desirable film performance; the 0.2 wt % agarose film exhibited the optimum efficacy in this work. [ABSTRACT FROM AUTHOR]

A cytocompatible method of surface-initiated, activator regenerated by electron transfer, atom transfer radical polymerization (SI-ARGET ATRP) is developed for engineering cell surfaces with synthetic polymers. Dopamine-based ATRP initiators are used for both introducing the ATRP initiator onto chemically complex cell surfaces uniformly (by the material-independent coating property of polydopamine) and protecting the cells from radical attack during polymerization (by the radical-scavenging property of polydopamine). Synthetic polymers are grafted onto the surface of individual yeast cells without significant loss of cell viability, and the uniform and dense grafting is confirmed by various characterization methods including agglutination assay and cell-division studies. This work will provide a strategic approach to the generation of living cell-polymer hybrid structures and open the door to their application in multitude of areas, such as sensor technology, catalysis, theranostics, and cell therapy. [ABSTRACT FROM AUTHOR]

Cell nanoencapsulation, generating cell-in-shell structures ('artificial spores'), provides a chemical toolbox for controlling the cellular behaviors and functional characteristics of individual cells. Among the shell materials studied so far, naturally occurring polyphenolic compounds, including polydopamine and tannic acid, have intensively been employed in cell-surface engineering, because their material-independent coating property eliminates an extra priming step for inducing subsequent shell formation. Albeit successful in generating cell-in-shell structures, the coating of polyphenolic compounds generally requires alkaline conditions and/or high salt conditions, which are not compatible with certain cell types. In this work, we demonstrate that the nanocoating of individual cells with a plant-derived phenolic compound, pyrogallol (1,2,3-trihydroxybenzene), occurs at mildly alkaline pH of 7.8 in an isotonic buffer. Three different cell types (anucleate, microbial, and mammalian cells) are coated with pyrogallol without noticeable decrease in cell viability. The protocol developed in this work could be applied to other polyphenolic compounds, and, considering the many polyphenols identified as a coating material, provides an advanced chemical tool in cell-surface engineering. [ABSTRACT FROM AUTHOR]

Reversible polymerization has a great potential for the generation of reusable nanomaterials and complete repair of cracks or breaks in self ‐ healing materials. In their Communication on page 908   ff., Young Hwan Jung et   al. report on a surface ‐ initiated, reversible polymerization of DNA that is processed by enzymatic reactions. Elongation of DNA, catalyzed by Taq DNA polymerase, is performed from a self ‐ priming oligodeoxynucleotide anchored onto gold, and reversible de ‐ polymerization and re ‐ polymerization are achieved in a sequence ‐ specific manner by using a restriction enzyme and Taq DNA polymerase. The cover picture was designed by Juno Lee. [ABSTRACT FROM AUTHOR]

Direct patterning of streptavidin and NIH 3T3 fibroblast cells was successfully achieved over a large-area pristine graphene sheet on Si/SO2 by aryl azide-based photografting with the conventional UV lithographic technique and surface-initiated, atom transfer radical polymerization of oligo(ethylene glycol) methacrylate. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we studied interfacial proton transfer of the self-assembled monolayer (SAM) of 1-(12-mercaptododecyl)imidazole on a gold electrode by faradaic impedance titration method with Fe(CN)6 3− as an anionic redox probe molecule. The surface pK 1/2 was found to be 7.3, which was nearly the same as that of 1-alkylimidazole in solution. We also investigated the electrochemical properties of the SAM-modified electrode by cyclic voltammetry. Cyclic voltammetry was performed (1) in the solution containing Fe(CN)6 3− with repeated alternation of pH values to investigate the electrostatic interaction of the protonated or deprotonated imidazole with Fe(CN)6 3− and (2) in the acidic or basic electrolyte containing Ru(NH3)6 3+ as a cationic redox probe to verify the effect of the polarity of a redox probe. We observed the reversible adsorption/desorption of Fe(CN)6 3− and concluded that the adsorbed Fe(CN)6 3− catalyzed the electron transfer of both Fe(CN)6 3− itself and cationic Ru(NH3)6 3+. [Copyright &y& Elsevier]

Facile tunability of physicochemical properties of ionic liquids (IL), particularly imidazolium ions bearing simple alkyl appendages as cations, has led to intense interest in IL as an alternative to conventional organic solvents in a range of synthesis, catalysis, electrochemistry and liquid-liquid extractions. Recent developments include their use for biopolymers,chemosensors for specific ions, determination of acidity scale and formation of nanosized metal particles and hollow metal oxide microspheres. The availability of potentially hydrophobic and hydrophilic IL attests to the ease in the manipulation of their physical properties.