Supramolecular Chiral Assembly of Dendritic Amphiphiles in Aqueous Media.

Dendritic amphiphiles are a promising class of topological blocks for self-assembly to construct chiral supramolecular aggregates in aqueous media. Their unique dendritic geometry, structure variability and multivalence can mediate the assemblies with versatile morphologies and functions. The bulky dendritic moieties also enable the appropriate association-repulsion balance to control supramolecular growth, and simultaneously shield the assemblies with enhanced stabilities.

Crowding for Confinement: Reversible Isomerization of First-Generation Donor-Acceptor Stenhouse Adduct Derivatives in Water Modulated by Thermoresponsive Dendritic Macromolecules.

Mimicking nature, the reversible isomerization of hydrophobic dyes in aqueous solutions is appealing for bio-applications. Here, we report on the reversible isomerization of first-generation solvatochromic donor-acceptor Stenhouse adducts (DASAs) in water within dendritic matrices, realized either through the dendronization of DASAs or the incorporation of DASA pendants into dendronized copolymers. These dendritic macromolecules contain three-fold dendritic oligoethylene glycols (OEGs), which afford the macromolecules water-solubility and unprecedented thermoresponsive behavior.

Hierarchical assembly of thermoresponsive helical dendronized poly(phenylacetylene)s through photo-crosslinking of the thermal aggregates.

Supramolecular assembly of helical homopolymers to form stable chiral entities in water is highly valuable for creating chiral nanostructures and fabricating chiral biomaterials. Here we report on thermally induced supramolecular assembly of helical dendronized poly(phenylacetylene)s (PPAs) in aqueous solutions, and their in-situ photo-crosslinking at elevated temperatures to afford crosslinked nano-assemblies with hierarchical structures and stabilized helicities. These helical dendronized homopolymers carry cinnamate-cored dendritic oligoethylene glycol (OEG) pendants, which exhibit characteristic thermoresponsive behavior.

Visible Light [2 + 2] Cycloadditions of Thermoresponsive Dendronized Styryltriazines To Exhibit Tunable Microconfinement.

Visible light-triggered photochemical reactions in aqueous media are highly valuable to tailor molecular structures and properties in an ecofriendly manner. Here we report visible light-induced catalyst-free [2 + 2] cycloadditions of thermoresponsive dendronized styryltriazines, which show tunable microconfinement to guest dyes in aqueous media. These dendronized styryltriazines are constituted of conjugated mono- or tristyryltriazines, which carry hydrophilic dendritic oligoethylene glycol (OEG) pendants.

Compressible Hydrogels with Stabilized Chirality from Thermoresponsive Helical Dendronized Poly(phenylacetylene)s.

Fabrication of chiral hydrogels from thermoresponsive helical dendronized phenylacetylene copolymers (PPAs) carrying three-fold dendritic oligoethylene glycols (OEGs) is reported. Three different temperatures, i.e.

Supramolecular assembly of dendronized diacetylenes into thermoresponsive chiral fibers and their covalent fixation through topochemical polymerization.

By combination of dendritic topological structures with photopolymerizable diacetylene, here we report on supramolecular chiral assembly of the dendronized diacetylenes in water. These dendronized diacetylenes are constituted with three-fold dendritic oligoethylene glycols (OEGs), bridged with a dipeptide from phenylalanine and glycine. These dendronized amphiphiles exhibit intensive propensity to aggregate in water and form helical fibers, which show characteristic thermoresponsive behavior with phase transition temperatures dominated by hydrophilicity of the dendritic OEGs.

An injectable thermoresponsive-hydrogel for lamellar keratoplasty: In-situ releases celastrol and hampers corneal scars.

Corneal stromal fibrosis is a common cause of visual impairment resulting from corneal injury, inflammation and surgery. Therefore, there is an unmet need for inhibiting corneal stromal fibrosis. However, bioavailability of topical eye drops is very low due to the tear and corneal barriers.

Dendronization of chitosan to afford unprecedent thermoresponsiveness and tunable microconfinement.

Convenient chemical modification of biomacromolecules to create novel biocompatible functional materials satisfies the current requirements of sustainable chemistry. Dendronization of chitosan with dendritic oligoethylene glycols (OEGs) paves a strategy for the preparation of functional dendronized chitosans (DCSs) with unprecedent thermoresponsive behavior, which inherit biological features from polysaccharides and the topological features from dendritic OEGs. In addition, densely packed dendritic OEG chains around the backbone provide efficient cooperative interactions and form an intriguing confined microenvironment based on the degradable biopolymers.

Thermoresponsive Helical Dendronized Poly(phenylacetylene)s: Remarkable Stabilization of Their Helicity via Photo-Dimerization of the Dendritic Pendants.

Dynamic helical polymers can change their helicity according to external stimuli due to the low helix-inversion barriers, while helicity stabilization for polymers is important for applications in chiral recognition or chiral separations. Here, we present a convenient methodology to stabilize dynamic helical conformations of polymers through intramolecular cross-linking. Thermoresponsive dendronized poly(phenylacetylene)s (PPAs) carrying 3-fold dendritic oligoethylene glycol pendants containing cinnamate moieties were synthesized.

Supramolecular assembly of dendronized spiropyrans in aqueous solutions into nanospheres with photo- and thermo-responsive chiralities.

Tailoring the amphiphilicity of a molecule through external stimuli can alter the balance between self-association and repulsion, resulting in different propensities for its assembly. Here we report on the supramolecular assembly of a series of dendronized spiropyrans (DSPs) in water. These DSPs carry 3-fold dendritic oligoethylene glycols (OEGs) with either methoxyl or ethoxyl terminals for different hydrophilicities, and contain an Ala-Gly dipeptide to provide the chirality.

Dual-Responsive Supramolecular Chiral Assemblies from Amphiphilic Dendronized Tetraphenylethylenes.

Supramolecular assembly of amphiphilic molecules in aqueous solutions to form stimuli-responsive entities is attractive for developing intelligent supramolecular materials for bioapplications. Here we report on the supramolecular chiral assembly of amphiphilic dendronized tetraphenylethylenes (TPEs) in aqueous solutions. Hydrophobic TPE moieties were connected to the hydrophilic three-fold dendritic oligoethylene glycols (OEGs) through a tripeptide proline-hydroxyproline-glycol (POG) to afford the characteristic topological structural effects of dendritic OEGs and the peptide linker.

Microfluidic Fabrication of Gelatin Acrylamide Microgels through Visible Light Photopolymerization for Cell Encapsulation.

Gelatin-based microgels are intriguing for various biomedical applications, which are conventionally prepared through photopolymerization of gelatin methacrylamide (GelMA). Here, we report on the modification of gelatin through acrylamidation to form gelatin acrylamide (GelA) with different substitution degrees, which was found to exhibit fast photopolymerization kinetics, better gelation, steady viscosity at elevated temperatures, and satisfying biocompatibility when compared to GelMA. By the online photopolymerization strategy with a home-made microfluidic setting, microgels of uniform sizes from GelA by blue light were obtained and their swollen properties were investigated.

Thermo-Gelling Dendronized Chitosans for Modulating Protein Activity.

Regulation of protein activity is important in their applications for biomedicine and therapeutics. Here, an approach for the regulation of protein bioactivity through molecular confinement provided by oligoethylene glycol (OEG)-based dendronized chitosan (DCS) hydrogels is reported. Structural effects on their thermoresponsiveness are investigated.

Dendronized Gelatin-Mediated Synthesis of Gold Nanoparticles.

Thermoresponsive dendronized gelatins () or gelatin methacrylates () were used as precursors to modulate the efficient reduction of Au(III) to form stable gold nanoparticles (AuNPs) through UV irradiation. These dendronized gelatins were obtained through the amidation of gelatin or gelatin methacrylates with dendritic oligoethylene glycols (OEGs). Crowded OEG dendrons along the gelatin backbones create a hydrophobic microenvironment, which promotes the reduction of Au(III).

Supramolecular Chiral Assembly of Symmetric Molecules with an Extended Conjugated Core.

C-symmetric molecules carrying a conjugated diacetylene (DA) core are found to self-assemble into well-defined supramolecular fibers with enhanced supramolecular chirality in both organic and aqueous solutions. The conjugated core affords these amphiphiles characteristic fluorescence properties, which can be quenched partially due to the aggregation. Integration of the C-symmetry with the conjugation provides these novel molecules strong aggregation tendency through solvent-mediated π-π stacking with preferential supramolecular chirality, which is predominately related to steric hindrance from their dipeptide pendants.

Thermoresponsive dendritic oligoethylene glycols.

Monodispersed molecules of low molar masses showing thermoresponsiveness are appealing both for mechanism investigation of the thermally-modulated dehydration and aggregation on molecular levels and for designing functional intelligent materials. In the present report, thermoresponsive properties of a homologous series of monodispersed dendritic macromolecules carrying three-, four- or six-fold dendritic oligoethylene glycol (OEG) segments were investigated. These dendritic macromolecules carry either methoxyl or ethoxyl terminals, and have different cores (alcohol, methyl ester or methacryloyl) to exhibit different overall hydrophilicity.

Thermoresponsive Supramolecular Assemblies from Dendronized Amphiphiles To Form Fluorescent Spheres with Tunable Chirality.

Balance between self-association of structural units and self-repulsion from crowding-induced steric hindrance accounts for the supramolecular assembly of the amphiphilic entities to form ordered structures, and solvation provides a toolbox to conveniently modulate the assemblies through differential interactions to various structural units. Here we report solvation-modulated supramolecular chiral assembly in aqueous solutions of amphiphilic dendronized tetraphenylethylenes (TPEs) with three-folded dendritic oligoethylene glycols (OEGs) through dipeptide Ala-Gly linkage. These dendronized amphiphiles can form supramolecular spheres with enhanced supramolecular chirality, which is tunable and dependent on solvation.

Dendronized polydiacetylenes photo-polymerization of supramolecular assemblies showing thermally tunable chirality.

Transformation of supramolecular chiral assemblies into covalent polymers integrates characteristics of supramolecular chemistry together with covalent entities, leading to fabrication of covalent chiral materials through versatile supramolecular chiral assemblies. Here, we report supramolecular assembly of an amphiphilic dendronized 10,12-pentacosadiynoic amide (PCDA) in aqueous solutions to form twisted ribbons, which were transferred into covalent dendronized polydiacetylenes (PDAs) photopolymerization. These supramolecular dendronized PCDA and the corresponding covalent dendronized PDAs showed unprecedent thermoresponsive properties.

Thermo-Gelling Dendronized Chitosans as Biomimetic Scaffolds for Corneal Tissue Engineering.

Biomimetic scaffolds with transparent, biocompatible, and in situ-forming properties are highly desirable for corneal tissue engineering, which can deeply fill corneal stromal defects with irregular shapes and support tissue regeneration. We here engineer a novel class of corneal scaffolds from oligoethylene glycol (OEG)-based dendronized chitosans (DCs), whose aqueous solutions show intriguing sol-gel transitions triggered by physiological temperature, resulting in highly transparent hydrogels. Gelling points of these hydrogels can be easily tuned, and furthermore, their mechanical strengths can be significantly enhanced when injected into PBS at 37 °C instead of pure water.

Acetylation of histone 3 promotes miR-29a expression and downregulates STAT3 in sepsis.

Background: MiR-29a targets signal transducers and activators of transcription 3 (STAT3) and negatively regulates its expression. Both miR-29a and STAT3 have been implicated in sepsis and upregulated miR-29a was associated with sepsis. However, the regulation of miR-29a in sepsis is not well elucidated.

Upper Critical Solution Temperature-Type Responsive Cyclodextrins with Characteristic Inclusion Abilities.

Water-soluble and thermoresponsive macrocycles with stable inclusion toward guests are highly valuable to construct stimuli-responsive supramolecular materials for versatile applications. Here, we develop such macrocycles - ureido-substituted cyclodextrins (CDs) which exhibit unprecedented upper critical solution temperature (UCST) behavior in aqueous media. These novel CD derivatives showed good solubility in water at elevated temperature, but collapsed from water to form large coacervates upon cooling to low temperature.

Evolution of Conformation, Nanomechanics, and Infrared Nanospectroscopy of Single Amyloid Fibrils Converting into Microcrystals.

Nanomechanical properties of amyloid fibrils and nanocrystals depend on their secondary and quaternary structure, and the geometry of intermolecular hydrogen bonds. Advanced imaging methods based on atomic force microscopy (AFM) have unravelled the morphological and mechanical heterogeneity of amyloids, however a full understanding has been hampered by the limited resolution of conventional spectroscopic methods. Here, it is shown that single molecule nanomechanical mapping and infrared nanospectroscopy (AFM-IR) in combination with atomistic modelling enable unravelling at the single aggregate scale of the morphological, nanomechanical, chemical, and structural transition from amyloid fibrils to amyloid microcrystals in the hexapeptides, ILQINS, IFQINS, and TFQINS.

Confined Microenvironments from Thermoresponsive Dendronized Polymers.

Confined microenvironments in biomacromolecules arising from molecular crowding account for their well-defined biofunctions and bioactivities. To mimick this, synthetic polymers to form confined structures or microenvironments are of key scientific value, which have received significant attention recently. To create synthetic confined microenvironments, molecular crowding effects and topological cooperative effects have been applied successfully, and the key is balance between self-association of structural units and self-repulsion from crowding-induced steric hindrance.