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Chiral induction by natural biomolecules can reveal the indispensable role of chiral structures in life and can be used to develop the chirality‐sensing biomolecular recognition. Here, we present the synthesis and characterization of an achiral supramolecular organic framework (SOF‐1) constructed from cucurbit[8]uril (CB[8]) and hexaphenylbenzene (HPB) derivative (1) in water. Due to the propeller‐like rotational chiral conformation of HPB units and the specific recognition properties of CB[8], SOF‐1 demonstrates chiral adaptive induction in water when interacting with the N‐terminal Trp‐/Phe‐containing dipeptides including L‐TrpX and L‐PheX (X is an amino acid residue), respectively, exhibiting contrasting circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. Consequently, SOF‐1 has been developed as a supramolecular host and chiroptical sensor capable of recognizing and distinguishing the sequence‐opposite Trp‐/Phe‐containing dipeptide pairs including L‐TrpX/L‐XTrp and L‐PheX/L‐XPhe based on the sequence‐selective CD responses. [ABSTRACT FROM AUTHOR]

Chiral framework materials have been developed for many applications including chiral recognition, chiral separation, asymmetric catalysis, and chiroptical materials. Herein, we report that an achiral cucurbit[8]uril‐based supramolecular organic framework (SOF‐1) with the dynamic rotational conformation of tetraphenylethene units can exhibit adaptive chirality to produce M‐SOF‐1 or P‐SOF‐1 with mirror‐image circular dichroism (CD) with gabs≈±10−4 and circularly polarized luminescence (CPL) with glum≈±10−4 induced by L‐/D‐phenylalanine in water, respectively. The chirality induction in CD (gabs≈−10−4) and CPL (glum≈−10−4) of P‐SOF‐1 from achiral SOF‐1 can be presented by using a small amount of adenosine‐5′‐triphosphate disodium (ATP) or adenosine‐5′‐diphosphate disodium (ADP) (only 0.4 equiv) in water. Furthermore, the adaptive chirality of SOF‐1 can be used to determine dipeptide sequences (e.g. Phe‐Ala and Ala‐Phe) and distinguish polypeptides/proteins (e.g. somatostatin and human insulin) with characteristic CD spectra. Therefore, achiral SOF‐1 as an ideal chiroptical platform with adaptive chirality may be applied to determine the enantiopurity of amino acids (e.g. L‐/D‐phenylalanine), develop aqueous CPL materials, and distinguish biological chiral macromolecules (e.g. peptides/proteins) via chirality induction in water. [ABSTRACT FROM AUTHOR]

Here, a series of shape‐controllable and fluorescent supramolecular organic frameworks (SOFs) exhibiting aggregation‐induced emission (AIE) are reported as a new kind of tunable luminescent material, constructed hierarchically from fluorescent guests (1–5) and cucurbit[8]uril (CB[8]) through homo/hetero host–guest complexation in water. These SOFs can further form regular supramolecular cuboids via a hierarchical assembly process in the solid state. Interestingly, the emission of hetero‐SOFs systems exhibiting AIE, which are a combination of two or three SOFs with two complementary colors (i.e., yellow and blue) or three primary RGB colors (red, green, and blue) through the hetero host–guest complexation between CB[8] and two pyridinium rings of different guests, can be easily tuned by adjusting the excitation wavelength and guests ratios, thereby achieving a wide‐color tunability (≈64% sRGB area) and white‐light emission (0.31, 0.34) in the solution state. This study therefore provides insight into the fabrication of tunable luminescent materials based on SOFs with controllable shapes and AIE properties as fluorescent platforms, and may facilitate the further design and synthesis of tunable luminescent materials and other fluorescent supramolecular systems based on host–guest complexation both in the solution and solid states. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of shape‐controllable and fluorescent supramolecular organic frameworks (cuboid or spheroid) are constructed hierarchically from CB[8] and tetraphenylethylene derivatives through host–guest interaction in water. These two fluorescent SOFs exhibit intriguing and varied photophysical properties, including large red‐shifts (up to 82 nm) and stimuli‐responsive behavior to competitive guest by binding with CB[8], the turn‐on fluorescence of which is applied in cellular imaging. [ABSTRACT FROM AUTHOR]

The global environmental challenge includes calls for emerging materials that can effectively clean up oil spillage from water. The fabrication and upgrading of sorbent materials with a high sorption capacity and excellent oil/water separation performance has become a high-profile topic today. Herein, for the first time, such a material is presented by assembling three-dimensional interconnected porous polystyrene fibers with a hydrophobic and oleophilic surface via successive electrospinning, showing superior performance in oil spillage cleanup. The key innovation point applied in this study is to produce a gradient structured system between these hierarchical fibres that can form gradient inter-fiber voids, resulting in a gradient capillary action force in the sorption process for oils. The as-designed super sorbent material exhibits high sorption capacity, as well as ultrafast sorption rates for various oils. The initial oil sorption amounts of the super sorbent material for pump oil, colza oil and diesel oil were approximated to 307.24 g g−1, 224.31 g g−1, and 84.52 g g−1, respectively, which are superior to those of other normal fibrous sorbents. Furthermore, the as-designed material, supported on a nonwoven fabric substrate exhibits outstanding performance for removing emulsified oil from water. More importantly, this superior material could be applied in industrial production because of its low cost and simple fabrication procedure. This study presents a facile strategy for the fabrication of efficient oil sorbents, providing a novel means for the upgrading of engineered sorption materials. [ABSTRACT FROM AUTHOR]

ABSTRACT The structural evolution of virgin and crosslinked polytetrafluoroethylene (PTFE) during stretching was studied by in situ synchrotron small-angle X-ray scattering (SAXS). Both yield and tensile stress of crosslinked PTFE increased with increasing crosslinking density. During stretching, for virgin PTFE, amorphous chains gradually turned to tensile direction at early stage, perpendicularly arranged lamellar stacks appeared at high strains (>140%). While for crosslinked PTFE, lamellar structure was observed even at lower strains; with increasing irradiation dose, the lamellar structure became obvious and the long period decreased. Four-point SAXS patterns were observed only in 3000kGy-dosed PTFE during deformation, which indicated that an alternately tilted lamella arrangement called herringbone structure was formed. Radiation dose induces crosslinked networks formed, which can carry part of local stress during deformation, resulting in the increase of yield and tensile stress. Crosslinking density is an important factor on structural evolution. In addition, a deformation mechanism of different crosslinked PTFE is proposed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39883. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers (CNF), representing the nano-structured cellulose, have attained an extensive research attention due to their sustainability, biodegradability, nanoscale dimensions, large surface area, unique optical and mechanical performance, etc. Different lengths of CNF can lead to different extents of entanglements or network-like structures through van der Waals forces. In this study, a series of polyvinyl alcohol (PVA) composite films, reinforced with CNF of different lengths, were fabricated via conventional solvent casting technique. CNF were extracted from jute fibers by tuning the dosage of sodium hypochlorite during the TEMPO-mediated oxidation. The mechanical properties and thermal behavior were observed to be significantly improved, while the optical transparency decreased slightly (Tr. > 75%). Interestingly, the PVA/CNF20 nanocomposite films exhibited higher tensile strength of 34.22 MPa at 2 wt% filler loading than the PVA/CNF10 (32.55 MPa) while displayed higher elastic modulus of 482.75 MPa than the PVA/CNF20 films (405.80 MPa). Overall, the findings reported in this study provide a novel, simple and inexpensive approach for preparing the high-performance polymer nanocomposites with tunable mechanical properties, reinforced with an abundant and renewable material. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) technology has shown great promise for the treatment of cancer and other genetic disorders. Despite the efforts to increase the target tissue distribution, the safe and effective delivery of siRNA to the diseased cells with sufficient cytosolic transport is another critical factor for successful RNAi clinical application. Here, the constructed lipid-based liquid crystalline nanoparticles, called nano-Transformers, can transform thestructure in the intracellular acidic environment and perform high-efficient siRNA delivery for cancer treatment. The developed nano-Transformers have satisfactory siRNA loading efficiency and low cytotoxicity. Different from the traditional cationic nanocarriers, the endosomal membrane fusion induced by the conformational transition of lipids contributes to the easy dissociation of siRNA from nanocarriers and direct release of free siRNA into cytoplasm. We show that transfection with cyclin-dependent kinase 1 (CDK1)-siRNA-loaded nano-Transformers causes up to 95% reduction of relevant mRNA in vitro and greatly inhibits the tumor growth without causing any immunogenic response in vivo. This work highlights that the lipid-based nano-Transformers may become the next generation of siRNA delivery system with higher efficacy and improved safety profiles.