Defining the structural parameters of triazole ligands in the templated synthesis of silver nanoparticles

This manuscript describes a one-pot method for the synthesis of size- and shape-selected silver nanoparticles (AgNPs) using Tollens' reagent [Ag(NH3)2OH] as the silver source. Sugar triazole ligands facilitate the formation of monodisperse AgNPs in which the size and shape can be controlled according to the reaction conditions. Increasing the size of the ligand reduces size tunability but enhances colloidal stability in high-salt buffers. A key conclusion from this study is that the AgI-binding affinity of these triazole ligands determines their capacity to tune the size of the resultant AgNPs formed. Weaker AgI-binding ligands can be used to form monodisperse, angular AgNPs over a wider range of sizes [(12 ± 3) to (33 ± 7) nm], whereas triazole ligands that exhibit a higher AgI-binding affinity produce monodisperse, spherical AgNPs of a single size [(18 ± 5) nm]

Splice-switching small molecules : a new therapeutic approach to modulate gene expression

Manipulating alternative RNA splicing events with small molecules is emerging as a viable mechanism for the development of therapeutics. A salient challenge in the field is understanding the molecular determinants defining the selectivity of splice-switching events and their mechanisms of action. In this review, the current state-of-the-art in splice-switching small molecules is described. Three examples of splice-switching small molecules are presented, and the differences in their modes of action compared

Orthogonal, metal-free surface modification by strain-promoted azide–alkyne and nitrile oxide–alkene/alkyne cycloadditions

In this article we present a fast and efficient methodology for biochemical surface patterning under extremely mild conditions. Micropatterned azide/benzaldoxime-surfaces were prepared by microcontact printing of a heterobifunctional cyclooctyne oxime linker on azide-terminated self-assembled monolayers (SAMs). Strain-promoted azide–alkyne cycloaddition (SPAAC) in combination with microcontact printing allows fast and effective surface patterning. The resulting bifunctional azide/oxime substrates could successfully be used for metal-free, orthogonal immobilization of various biomolecules by 1,3-dipolar cycloadditions at room temperature. Azide-decorated areas were modified by reaction with a cyclooctyne-conjugate using SPAAC, while benzaldoxime-decorated areas were activated by in situ oxidation to the reactive nitrile oxides and subsequent nitrile oxide cycloaddition with alkene- and alkyne-functionalized bioconjugates. In addition, orthogonal double immobilization was achieved by consecutive and independent SPAAC and nitrile oxide cycloadditions

Organic semiconductor laser biosensor : design and performance discussion

Organic distributed feedback lasers can detect nanoscale materials and are therefore an attractive sens- ing platform for biological and medical applications. In this paper, we present a model for optimizing such laser sensors and discuss the advantages of using an organic semiconductor as the laser material in comparison to dyes in a matrix. The structure of the sensor and its operation principle are described. Bulk and surface sensing exper- imental data using oligofluorene truxene macromolecules and a conjugated polymer for the gain region is shown to correspond to modeled values and is used to assess the biosensing attributes of the sensor. A comparison between organic semiconductor and dye-doped laser sensitivity is made and analyzed theoretically. Finally, experimental and theoretical specific biosensing data is provided and methods for improving sensitivity are discussed

Site-Specific Assembly of DNA-Based Photonic Wires by Using Programmable Polyamides**

The first example of a programmable DNA photonic wire is reported utilizing fluorophore-tethered pyrrole-imidazole polyamides for site-directed fluorophore assembly along a pre-formed DNA duplex (see scheme; PB=Pacific Blue, Cy3=Cyanine 3; orange rectangles=fluorophore). The importance of such control is revealed by efficient energy transport over distances in excess of 27 nm

Reversible DNA micro-patterning using the fluorous effect

We describe a new method for the immobilisation of DNA into defined patterns with sub-micron resolution, using the fluorous effect. The method is fully reversible via a simple solvent wash, allowing the patterning, regeneration and re-patterning of surfaces with no degradation in binding efficiency following multiple removal/attachment cycles of different DNA sequences

Transition-metal-free amine oxidation : a chemoselective strategy for the late-stage formation of lactams

A metal-free strategy for the formation of lactams via selective oxidation of cyclic secondary and tertiary amines is described. Molecular iodine facilitates both chemoselective and regioselective oxidation of C–H bonds directly adjacent to a cyclic amine. The mild conditions, functional group tolerance, and substrate scope are demonstrated using a suite of diverse small molecule cyclic amines, including clinically approved drug scaffolds

Whisky tasting using a bimetallic nanoplasmonic tongue

Metallic nanostructures are ideal candidates for optical tongue devices thanks to their chemical stability, the sensitivity of their plasmonic resonance to environmental changes, and their ease of chemical-functionalization. Here, we describe a reusable optical tongue comprised of multiplexed gold and aluminum nano-arrays; a bimetallic device which produces two distinct resonance peaks for each sensing region. Through specific modification of these plasmonic arrays with orthogonal surface chemistries, we demonstrate that a dual-resonance device allows us to halve sensor sizes and data-acquisition times when compared to single-resonance, monometallic devices. We applied our bimetallic tongue to differentiate off-the-shelf whiskies with > 99.7% accuracy by means of linear discriminant analysis (LDA). This advance in device miniaturization, functionalization, and multiplexed readout indicates nanoplasmonic tongues will have future applications in chemical mixture identification in applications where portability, reusability, and measurement speed are key

S-Adenosyl Methionine Cofactor Modifications Enhance the Biocatalytic Repertoire of Small Molecule C-Alkylation

A tandem enzymatic strategy to enhance the scope of Calkylation of small molecules via the in situ formation of S-adenosyl methionine (SAM) cofactor analogues is described. A solventexposed channel present in the SAM-forming enzyme SalL tolerates 5'-chloro-5’-deoxyadenosine (ClDA) analogues modified at the 2position of the adenine nucleobase. Coupling SalL-catalyzed cofactor production with C-(m)ethyl transfer to coumarin substrates catalyzed by the methyltransferase (MTase) NovO forms C(m)ethylated coumarins in superior yield and greater substrate scope relative to that obtained using cofactors lacking nucleobase modifications. Establishing the molecular determinants which influence C-alkylation provides the basis to develop a late-stage enzymatic platform for the preparation of high value small molecule