Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli.

In our continuing pursuit to generate, understand, and control the morphology of organic nanofilaments formed by molecules with a bent molecular shape, we here report on two bent-core molecules specifically designed to permit a phase or morphology change upon exposure to an applied electric field or irradiation with UV light. To trigger a response to an applied electric field, conformationally rigid chiral (,)-2,3-difluorooctyloxy side chains were introduced, and to cause a response to UV light, an azobenzene core was incorporated into one of the arms of the rigid bent core. The phase behavior as well as structure and morphology of the formed phases and nanofilaments were analyzed using differential scanning calorimetry, cross-polarized optical microscopy, circular dichroism spectropolarimetry, scanning and transmission electron microscopy, UV-vis spectrophotometry, as well as X-ray diffraction experiments.

Chirality Transfer from an Innately Chiral Nanocrystal Core to a Nematic Liquid Crystal 2: Lyotropic Chromonic Liquid Crystals.

The importance of and the difference between molecular versus structural core chirality of substances that form nanomaterials, and their ability to transmit and amplify their chirality to and within a surrounding condensed medium is yet to be exactly understood. Here we demonstrate that neat as well as disodium cromoglycate (DSCG) surface-modified cellulose nanocrystals (CNCs) with both molecular and morphological core chirality can induce homochirality in racemic nematic lyotropic chromonic liquid crystal (rac-N-LCLC) tactoids. In comparison to the parent chiral organic building blocks, D-glucose, endowed only with molecular chirality, both CNCs showed a superior chirality transfer ability.

Well-Defined Polyethylene Glycol Microscale Hydrogel Blocks Containing Gold Nanorods for Dual Photothermal and Chemotherapeutic Therapy.

Local drug delivery offers a means of achieving a high concentration of therapeutic agents directly at the tumor site, whilst minimizing systemic toxicity. For heterogenous cancers such as glioblastoma, multimodal therapeutic approaches hold promise for better efficacy. Herein, we aimed to create a well-defined and reproducible drug delivery system that also incorporates gold nanorods for photothermal therapy.

Chirality Transfer from an Innately Chiral Nanocrystal Core to a Nematic Liquid Crystal: Surface-Modified Cellulose Nanocrystals.

The vast majority of nanomaterials studied in light of their ability to transmit chirality to or amplify their chirality in a surrounding medium, constitute an achiral core with chirality solely installed at the surface by conjugation or encapsulation with optically active ligands. Here we present the inverse approach focusing on surface-modified cellulose nanocrystals (CNCs) with core chirality at both the molecular and the morphological level to quantify transmission and amplification of core chirality through space using a host nematic liquid crystal (N-LC) as reporter. We find that CNCs functionalized at the surface with achiral molecules, structurally related to the N-LC, exhibit better N-LC solubility, thereby serving as highly efficient chiral inducers.

Enhanced targeting of invasive glioblastoma cells by peptide-functionalized gold nanorods in hydrogel-based 3D cultures.

Unlabelled: Cancer stem cells (CSCs) are responsible for drug resistance, tumor recurrence, and metastasis in several cancer types, making their eradication a primary objective in cancer therapy. Glioblastoma Multiforme (GBM) tumors are usually composed of a highly infiltrating CSC subpopulation, which has Nestin as a putative marker. Since the majority of these infiltrating cells are able to elude conventional therapies, we have developed gold nanorods (AuNRs) functionalized with an engineered peptide capable of specific recognition and selective eradication of Nestin positive infiltrating GBM-CSCs.

Photoresponsive Formation of an Intermolecular Minimal G-Quadruplex Motif.

The ability of three different bifunctional azobenzene linkers to enable the photoreversible formation of a defined intermolecular two-tetrad G-quadruplex upon UV/Vis irradiation was investigated. Circular dichroism and NMR spectroscopic data showed the formation of G-quadruplexes with K(+)  ions at room temperature in all three cases with the corresponding azobenzene linker in an E conformation. However, only the para-para-substituted azobenzene derivative enables photoswitching between a nonpolymorphic, stacked, tetramolecular G-quadruplex and an unstructured state after E-Z isomerization.

Ultrafast dynamics of a spiropyran in water.

The reversible switching of a water-soluble spiropyran compound is recorded over 1 ns by means of femtosecond vis-pump/vis- and IR-probe spectroscopy under aqueous conditions. Our investigations reveal that the photochemical conversion from the closed spiropyran to the open merocyanine takes 1.6 ps whereas the reversed photoreaction is accomplished within 25 ps.

DNA minicircles connected via G-quadruplex interaction modules.

G-quadruplexes are becoming reliable alternative interaction modules for the construction of DNA nanoarchitectures due to their prompt inducibility by salts. In this Full Paper, we report the design and synthesis of two different DNA minicircles equipped with G-rich appendixes that can self-hybridize into a G-quadruplex, which acts as a DNA recruiter and glue. Both minicircles, one containing a hairpin-like G-rich region and the other an open tuning-fork-like G-rich region, have the potential to form DNA G-nanoconstructs but only the tuning-fork minicircle does so.

Inhibition of dicing of guanosine-rich shRNAs by quadruplex-binding compounds.

RNA interference is triggered by small hairpin precursors that are processed by the endonuclease dicer to yield active species such as siRNAs and miRNAs. To regulate the RNAi-mediated suppression of gene expression, we imagined a strategy that relies on the sequence-specific inhibition of shRNA precursor processing by immediate RNA-small molecule interactions. Here, we present a first step in this direction by augmenting shRNAs with guanosine-rich sequences that are prone to fold into four-stranded structures.

Tetramethylpyridiniumporphyrazines--a new class of G-quadruplex inducing and stabilising ligands.

3,4-Tetramethylpyridiniumporphyrazines bind strongly and selectively to human telomeric G-quadruplex DNA, inducing the formation of an antiparallel quadruplex in a process that mimics molecular chaperones.

Synthesis and G-quadruplex binding studies of new 4-N-methylpyridinium porphyrins.

A series of cationic porphyrins carrying 1-3 meso-N-pyridinium groups has been synthesised, and their binding to G-quadruplex DNA has been explored by surface plasmon resonance (SPR) and circular dichroism spectroscopy. Two trans substituents appear to be sufficient for tight binding; preferential binding to the anti-parallel intramolecular human telomeric DNA was observed for the A2trans and A3 porphyrins. The A2trans is able to induce the formation of an anti-parallel G-quadruplex in a K+ free solution, mimicking the effect of a molecular chaperone.