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We introduced an aptamer switch design that relies on the ability of post-transition/transition metal ions to trigger, through their coordination to nucleobases, substantial DNA destabilization. In the absence of molecular target, the addition of one such metal ion to usual aptamer working solutions promotes the formation of an alternative, inert DNA state. Upon exposure to the cognate compound, the equilibrium is shifted towards the competent DNA form. The switching process was preferentially activated by metal ions of intermediate base over phosphate complexation preference ( i.e. Pb 2+ , Cd 2+ ) and operated with diversely structured DNA molecules. This very simple aptamer switch scheme was applied to the detection of small organics using the fluorescence anisotropy readout mode. We envision that the approach could be adapted to a variety of signalling methods that report on changes in the surface charge density of DNA receptors.

A new approach for improving the mechanical properties of semiconducting polymers was established via physical combination of a diketopyrrolopyrrole-based conjugated polymer with a low-molecular-we...

A new methodology to covalently cross-link π-conjugated polymers by generating π-conjugated bridges was developed through the topochemical polymerization of 1,3-butadiyne moieties. Isoindigo-based ...

An efficient strategy to modulate the mechanical properties of conjugated polymers has been developed through the incorporation of amide-containing alkyl chains in diketopyrrolopyrrole-based conjugated polymers. The side-chain engineering performed with hydrogen bonding moieties (up to 20 mol% of amide-containing side-chains) was found to reduce the crystallinity of the conjugated polymers in the solid state. Interestingly, this reduction in crystallinity drastically influenced the mechanical properties of the new DPP-polymers, by promoting their stretching ability, reducing the elastic modulus of the polymers, and facilitating the molecular alignment after stretch. The resulting polymers with 10% hydrogen bonding side chains showed a maximum stretchability of 75% elongation, without the appearance of nanoscale cracks, and a detailed investigation of the mechanical properties was performed by a combination of morphological characterization tools, including grazing-incidence X-ray diffraction, polarized UV-Vis spectroscopy and optical/atomic force microscopy to support our finding. Additionally, incorporation of amide-containing side-chains also enabled the regeneration of the conjugated polymer morphology after damage. Our results demonstrate that the introduction of amide-containing alkyl chains is an effective strategy to enhance the mechanical properties of π-conjugated polymers without disrupting the π-conjugation, and to enable new properties such as morphological healing.

In this work, a facile and simple yet effective method to generate intrinsic autonomous self-healing polymers was developed, leading to new materials that can be easily fine-tuned both mechanically and chemically. The new materials were designed to incorporate two dynamic and reversible types of chemical bonds, namely dynamic imine and metal-coordinating bonds, to enable autonomous self-healing, controlled degradability and ultra-high tunable stretchability (up to 800% strain) based on the ratio of metal to ligand incorporated. Through an easy condensation reaction, imine bonds are generated at the end-termini of a short siloxane chain. The new dynamic system was characterized by a variety of techniques, including tensile-pull strain testing, atomic force microscopy and UV-Vis spectroscopy, which showed that the highly dynamic imine bonds, combined with coordination with Fe2+ ions, allow for the material to regenerate 88% of its mechanical strength after physical damage. The materials were also controlled to be degraded in mild acidic conditions. Lastly, application in self-healable electronics was demonstrated through the fabrication of a capacitive-based pressure sensor, which shows good sensitivity and dynamic response (∼0.33 kPa-1) before and after healing.

A new strategy for influencing the solid-state morphology of conjugated polymers was developed through physical blending with a low-molecular-weight branched polyethylene. This nontoxic and low-boiling-point additive was blended with a high-charge-mobility diketopyrrolopyrrole-based conjugated polymer, and a detailed investigation of the new blended materials was performed by various characterization tools, including X-ray diffraction, UV-vis spectroscopy, and atomic force microscopy. Interestingly, the branched additive was shown to reduce the crystallinity of the conjugated polymer while promoting aggregation and phase separation in the solid state. Upon thermal removal of the olefinic additive, the thin films maintained a lower crystallinity and aggregated morphology in comparison to a nonblended polymer. The semiconducting performance of the new branched polyethylene/conjugated polymer blends was also investigated in organic field-effect transistors, which showed a stable charge mobility of around 0.3 cm