Block copolymers self-assemble into a variety of nanostructures that are relevant for science and technology. While the assembly of diblock copolymers is largely understood, predicting the solution assembly of triblock terpolymers remains challenging due to complex interplay of block/block and block/solvent interactions. Here we provide guidelines for the self-assembly of linear ABC triblock terpolymers into a large variety of multicompartment nanostructures with C corona and A/B cores. The ratio of block lengths NC/NA thereby controls micelle geometry to spheres, cylinders, bilayer sheets and vesicles. The insoluble blocks then microphase separate to core A and surface patch B, where NB controls the patch morphology to spherical, cylindrical, bicontinuous and lamellar. The independent control over both parameters allows constructing combinatorial libraries of unprecedented solution nanostructures, including spheres-on-cylinders/sheets/vesicles, cylinders-on-sheets/vesicles, and sheets/vesicles with bicontinuous or lamellar membrane morphology (patchy polymersomes). The derived parameters provide a logical toolbox towards complex self-assemblies for soft matter nanotechnologies.
The transfer of chirality across length-scales is an intriguing and universal natural phenomenon. However, connecting the properties of individual building blocks to the emergent features of their resulting large-scale structure remains a challenge. In this work, we investigate the origins of mesophase chirality in cellulose nanocrystal suspensions, whose self-assembly into chiral photonic films has attracted significant interest. By correlating the ensemble behaviour in suspensions and films with a quantitative morphological analysis of the individual nanoparticles, we reveal an inverse relationship between the cholesteric pitch and the abundance of laterally-bound composite particles. These ‘bundles’ thus act as colloidal chiral dopants, analogous to those used in molecular liquid crystals, providing the missing link in the hierarchical transfer of chirality from the molecular to the colloidal scale.
Nanocelluloses with native crystalline internal structures have attracted considerable interest due to their plant-based origin, high mechanical properties, modifiability, and chiral liquid crystallinity, which suggest novel functional sustainable materials. [1−27] In particular, cellulose nanocrystals (CNCs) are colloidal rods, having a typical lateral dimension of 5−10 nm and length of 50−300 nm. Above a critical aqueous concentration, they exhibit lefthanded chiral nematic (cholesteric) liquid crystallinity (LC) and optical iridescence, [4][5][6] which is preserved in dried films [4,28] . It allows templating for photonic materials using inorganics, nanoparticles, polymers, and pyrolyzed carbonized matter. [10,12,16,25,26] On the other hand, the CNCs have been suggested to possess a right-handed twist along their nanorod axis to explain the left-handed twist in their chiral LC. [6] Recently, the right-handed twist of individual CNCs and nanocelluloses of three different origins was observed by cryo-electron tomography (cryo-ET), and electron and atomic force microscopy [27,29] supported by molecular dynamics simulations [30−32] .Exploiting the twisting shape along the individual CNC nanorods could allow new optical functions in the nano/colloidal scale in dilute aqueous dispersions, i.e. not limited to the chiral LC based on the inter-rod assembly involving a larger length scale. Surprisingly, such optical findings have not been reported so far.Surface plasmons, i.e. collective oscillations of the conduction electrons on metal surfaces, allow physics and applications ranging from photonic devices, sensing, and solar cells to pharmacology. [33−37] In nanoparticles (NPs) the oscillations become coupled to allow a chiral plasmonic response, provided that they are sufficiently closely positioned and assembled in a chiral manner. This manifests in circular dichroism (CD) spectroscopy, which describes the difference in absorption between left-and right-handed circularly polarized light. The chiral coupling of surface plasmons induces a bisignated CD signal with a zerocrossing at the characteristic localized surface plasmon resonance wavelength of the isolated NPs. Such a Cotton effect is either dip−peak or peak−dip, depending on the handedness of chirality. [38−42] In chiral biological molecules, such as DNA, proteins and polypeptides, the CD signal is at ultraviolet wavelengths, whereas the CD signal of helical metal nanoparticle assemblies is at the visible wavelengths. This extends the applications to e.g. in biosensing. [37] Chiral nanoparticle assemblies have been shown using helical polymers, supramolecular fibers, and DNA-based constructs as templates. [40−42] In particular, a chiral plasmonic signal is obtained using DNA-origami to organize the nanoparticles in well-defined helices with tunable pitch, separation, and handedness. [40,41] Even if the above approaches are promising allowing in-depth tunable chiral plasmonic response, introducing rapid, scalable, and economic ways for producing chiral plas...
Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents.
Cellulose nanocrystals (CNCs) are high aspect ratio colloidal rods with nanoscale dimensions, attracting considerable interest recently due to their high mechanical properties, chirality, sustainability, and availability. In order to exploit them for advanced functions in new materials, novel supracolloidal concepts are needed to manipulate their self-assemblies. We report on exploring multivalent interactions to CNC surface and show that dendronized polymers (DenPols) with maltose-based sugar groups on the periphery of lysine dendrons and poly(ethylene-alt-maleimide) polymer backbone interact with CNCs. The interactions can be manipulated by the dendron generation suggesting multivalent interactions. The complexation of the third generation DenPol (G3) with CNCs allows aqueous colloidal stability and shows wrapping around CNCs, as directly visualized by cryo high-resolution transmission electron microscopy and electron tomography. More generally, as the dimensions of G3 are in the colloidal range due to their ~6 nm lateral size and mesoscale length, the concept also suggests supracolloidal multivalent interactions between other colloidal objects mediated by sugar-functionalized dendrons giving rise to novel colloidal level assemblies.
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