Chiral Hydrogel Nerve Conduit Boosts Peripheral Nerve Regeneration via Regulation of Schwann Cell Reprogramming.

The Schwann cell (SC) is essential in peripheral nerve regeneration by reprogramming into a stem-like "repair Schwann cell" (rSC) phenotype; however, maintaining the rSC stemness remains an unmet challenge. Chirality is a fundamental factor controlling cell fate, and its potential role in regulation of SC reprogramming has long been ignored and remains poorly understood. Herein, inspired by natural chiral components in the SC microenvironment, chiral hydrogel nerve conduits are prepared by supramolecular assembly of l/d-phenylalanine derivatives (l/d-Phe) in polymeric chitosan-gelatin conduits.

Mxene-Based Supramolecular Composite Hydrogels for Antioxidant and Photothermal Antibacterial Activities.

Bacterial infections and oxidative damage caused by various reactive oxygen species (ROS) pose a significant threat to human health. It is highly desirable to find an ideal biomaterial system with broad spectrum antibacterial and antioxidant capabilities. A new supramolecular antibacterial and antioxidant composite hydrogel made of chiral L-phenylalanine-derivative (LPFEG) as matrix and Mxene (Ti C T ) as filler material is presented.

Molecular Polarizability Regulated Piezoelectricity of Organic Materials from Single-Molecular Level.

Although molecular piezoelectric materials are ideal constituents for next-generation electronic microdevices, their weak piezoelectric coefficients which restrict their practical applications need to be enhanced by some strategies. Herein, a series of d-phenylalanine derivatives are synthesized and an increased molecular piezoelectric coefficient of their assemblies is achieved by acid doping. The acid doping can increase the asymmetric distribution of charges in the molecules and in turn molecular polarizability, leading to the enhanced molecular piezoelectricity of assemblies.

Infected Diabetic Wound Regeneration Using Peptide-Modified Chiral Dressing to Target Revascularization.

Revascularization plays a critical role in the healing of diabetic wounds. Accumulation of advanced glycation end products (AGEs) and refractory multidrug resistant bacterial infection are the two major barriers to revascularization, directly leading to impaired healing of diabetic wounds. Here, an artfully designed chiral gel dressing is fabricated (named as HA-LM2-RMR), which consists of l-phenylalanine and cationic hexapeptide coassembled helical nanofibers cross-linked with hyaluronic acid via hydrogen bonding.

Chirality-influenced antibacterial activity of methylthiazole- and thiadiazole-based supramolecular biocompatible hydrogels.

Chiral stereochemistry is a unique and fundamental strategy that determines the interaction of bacteria cells with chiral biomolecules and stereochemical surfaces. The interaction between bacteria and material surface (molecular chirality or supramolecular chirality) plays a significant role in modulating antibacterial performance. Herein, we developed inherent chiral antibacterial hydrogels by modifying the carboxyl groups of our previously reported supramolecular gelator (LPF-left handed phenylalanine gelator and DPF- right handed phenylalanine gelator) with 2-amino-5-methylthiazole (MTZ) and 5-amino-1,3,4-thiadiazole-2- thiol (TDZ).

Antimicrobial Activity with Enhanced Mechanical Properties in Phenylalanine-Based Chiral Coassembled Hydrogels: The Influence of Pyridine Hydrazide Derivatives.

Hydrazide derivatives are known to display a wide range of biological properties including antimicrobial activities, hence making them desirable candidates for soft biomaterials. Herein, we report chiral supramolecular coassembled hydrogels obtained from two phenylalanine gelators (L/DPF and B2L/D) and two dicarbohydrazide molecules (pyridine-2,6-dicarbohydrazide (PDH) and (2,2'-bipyridine)-5,5'-dicarbohydrazide (BDH)) that exhibited enhanced mechanical properties, chirality modulation, and antimicrobial activity. Four lines of coassembled hydrogels were obtained (.

Mechanically Stable C2-Phenylalanine Hybrid Hydrogels for Manipulating Cell Adhesion.

Tuning of the viscoelastic properties of supramolecular hydrogels to be used as biological material substrates in tissue engineering has become significantly relevant in recent years due to their ability to influence cell fate. In the quest to enhance the stability and mechanical properties of a derived C2-phenylalanine gelator (LPF), derivatives of the polysaccharide dextran were incorporated as additives to promote hydrogen bonding and π-π stacking with the gelator. Dextran was esterified to yield carboxymethyl dextran (CMDH), which was subsequently amidated to furnish amino dextran (AD), the resulting hybrid hydrogels were denoted as LPF-AD and LPF-CMDH, where represents the amount of AD and CMDH (mg).

Inversion of Circularly Polarized Luminescence of Nanofibrous Hydrogels through Co-assembly with Achiral Coumarin Derivatives.

Control over the handedness of circularly polarized luminescence (CPL) in supramolecular gels is of special significance in biology and optoelectronics; however, it still remains a great challenge to precisely and efficiently regulate the chirality of CPL. Herein, a chiral phenylalanine-derived hydrogelator and achiral coumarin derivatives can co-assemble into nanofibrous hydrogels with controllable chirality, and the handedness of CPL of these hydrogels can be efficiently inverted by coumarin derivatives through noncovalent interactions, which can be further tuned at will by incorporating metal ions into the co-assembly. The hydrogen bonds, coordination interactions, and steric hindrance are proved to be the crucial factors for the CPL inversion.

Chirality-Enabled Liquid Crystalline Physical Gels with High Modulus but Low Driving Voltage.

Self-supporting liquid crystalline physical gels with facile electro-optic response are highly desirable, but their development is challenging because both the storage modulus and driving voltage increase simultaneously with gelator loading. Herein, we report liquid crystalline physical gels with high modulus but low driving voltage. This behavior is enabled by chirality transfer from the molecular level to three-dimensional fibrous networks during the self-assembly of 1,4-benzenedicarboxamide phenylalanine derivatives.

Metal-Ion-Mediated Supramolecular Chirality of l-Phenylalanine Based Hydrogels.

For chiral hydrogels and related applications, one of the critical issues is how to control the chirality of supramolecular systems in an efficient way, including easy operation, efficient transfer of chirality, and so on. Herein, supramolecular chirality of l-phenylalanine based hydrogels can be effectively controlled by using a broad range of metal ions. The degree of twisting (twist pitch) and the diameter of the chiral nanostructures can also be efficiently regulated.

Stoichiometry-Controlled Inversion of Supramolecular Chirality in Nanostructures Co-assembled with Bipyridines.

To control supramolecular chirality of the co-assembled nanostructures, one of the remaining issues is how stoichiometry of the different molecules involved in co-assembly influence chiral transformation. Through co-assembly of achiral 1,4-bis(pyrid-4-yl)benzene and chiral phenylalanine-glycine derivative hydrogelators, stoichiometry is found to be an effective tool for controlling supramolecular chirality inversion processes. This inversion is mainly mediated by a delicate balance between intermolecular hydrogen bonding interactions and π-π stacking of the two components, which may subtly change the stacking of the molecules, in turn, the self-assembled nanostructures.

Amino Acids and Peptide-Based Supramolecular Hydrogels for Three-Dimensional Cell Culture.

Supramolecular hydrogels assembled from amino acids and peptide-derived hydrogelators have shown great potential as biomimetic three-dimensional (3D) extracellular matrices because of their merits over conventional polymeric hydrogels, such as non-covalent or physical interactions, controllable self-assembly, and biocompatibility. These merits enable hydrogels to be made not only by using external stimuli, but also under physiological conditions by rationally designing gelator structures, as well as in situ encapsulation of cells into hydrogels for 3D culture. This review will assess current progress in the preparation of amino acids and peptide-based hydrogels under various kinds of external stimuli, and in situ encapsulation of cells into the hydrogels, with a focus on understanding the associations between their structures, properties, and functions during cell culture, and the remaining challenges in this field.

Inversion of the Supramolecular Chirality of Nanofibrous Structures through Co-Assembly with Achiral Molecules.

To understand the behavior of chiral nanostructures, it is of critical importance to study how achiral molecules regulate the chirality of such nanostructures and what the main driving forces for the regulation processes are. In this work, the supramolecular chirality of helical nanofibers consisting of phenylalanine-based enantiomers is inverted by achiral bis(pyridinyl) derivatives through co-assembly. This inversion is mainly mediated by intermolecular hydrogen bonding interactions between the achiral additives and the chiral molecules, which may induce stereoselective interactions and different reorientations for the assembled molecules, as confirmed by calculations.

Installing Logic Gates to Multiresponsive Supramolecular Hydrogel Co-assembled from Phenylalanine Amphiphile and Bis(pyridinyl) Derivative.

Recently, logic gates based on multiresponsive hydrogel systems are attractive because of their potential biological applications. A quite simple supramolecular hydrogel co-assembled from phenylalanine-based amphiphile (LPF2) and bis(pyridinyl) derivative (AP) is constructed. The co-assembled hydrogel exhibited a macroscopic gel-sol transition in response to four distinct input stimuli: temperature, acid, base, and light.

Multiresponsive hydrogel coassembled from phenylalanine and azobenzene derivatives as 3D scaffolds for photoguiding cell adhesion and release.

A multiresponsive hydrogel system coassembled from phenylalanine derivative gelator (LPF2) and azobenzene (Azo) derivative (PPI) is constructed, which can respond to temperature, pH, host-guest interaction, and photoirradiation. A set of techniques including circular dichroism, Fourier transform infrared spectroscopy, (1)H NMR, and X-ray powder diffraction confirm that the hydrogel is formed through hydrogen bonds between amide moieties/pyridine and carbonyl groups, enduing the coassembled hydrogel with multiresponsive properties that make it possible to control cell encapsulation and release in three-dimensional environments under multistimulus, for example, UV irradiation. This study brings a novel approach to develop multistimuli-responsive hydrogels by coassembly of various responsive components for biomedical interest, for example, the controlled delivery of various therapeutic biological agents.

Control of three-dimensional cell adhesion by the chirality of nanofibers in hydrogels.

In the three-dimensional (3D) extracellular matrix (ECM), the influence of nanofiber chirality on cell behavior is very important; the helical nanofibrous structure is closely related to the relevant biological events. Herein, we describe the use of the two enantiomers of a 1,4-benzenedicarboxamide phenylalanine derivative as supramolecular gelators to investigate the influence of the chirality of nanofibers on cell adhesion and proliferation in three dimensions. It was found that left-handed helical nanofibers can increase cell adhesion and proliferation, whereas right-handed nanofibers have the opposite effect.

Convenient three-dimensional cell culture in supermolecular hydrogels.

A convenient three-dimensional cell culture was developed by employing high swelling property of hybrid hydrogels coassembled from C2-phenyl-based supermolecular gelators and sodium hyaluronate. Imaging and spectroscopic analysis by scanning electron microscopy (SEM), atomic force microscopy (AFM), transform infrared (FT-IR) spectra confirm that the hybrid gelators can self-assemble into nanofibrous hydrogel. The high swelling property of dried gel ensures cell migration and proliferation inside bulk of the hydrogels, which provides a facial method to study disease models, the effect of drug dosages, and tissue culture in vitro.

Wettability of supramolecular nanofibers for controlled cell adhesion and proliferation.

By employing smart self-assembly of 1,4-benyldicarbonxamide-phenylalanine (C2) derived supramolecular gelators, a simple way to construct nanofibrous environments with the controllable wettability is developed. The fast cell adhesion and proliferation on the least wettable fibers indicates an efficient control over cells, which is proved to be mainly mediated by the interaction between protein and the fibers. One typical merit superior to other materials is that cell adhesion can be regulated not only on two-dimensional (2D) substrates but also in three-dimensional (3D) microenvironments.

RGD anchored C-benzene based PEG-like hydrogels as scaffolds for two and three dimensional cell cultures.

Designing new types of cell scaffolds to resist protein adsorption and promote cell adhesion is becoming very important in the field of tissue engineering. Herein, by coupling ethylene glycol (EG) monomers and Arg-Gly-Asp (RGD) onto C-benzene cores, a family of PEG-like low molecular weight gelators (LMWGs) functionalized with RGD is reported. Imaging and spectroscopic analysis by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Circular Dichroism (CD) spectroscopy confirm that the functionalized LMWGs can self-assemble into nanofibrous hydrogels.

Dual-specific interaction to detect DNA on gold nanoparticles.

An approach to selectively and efficiently detect single strand DNA is developed by using streptavidin coated gold nanoparticles (StAuNPs) as efficient quenchers. The central concept for the successful detection is the combination the of streptavidin-biotin interaction with specific probe-target DNA hybridization. Biotin labeled probe DNAs act as "bridges" to bring Cy5 labeled targets to the particle surface and the fluorophore dye can be rapidly and efficiently quenched by StAuPNs.

Gelator-polysaccharide hybrid hydrogel for selective and controllable dye release.

In this paper, 1,4-bi(phenylalanine-diglycol)-benzene (PDB) based Low-Molecular-Weight-Gelator (LMWG) hydrogels are modified using hydrophilic polysaccharide (sodium alginate). A set of techniques including Fourier transform infrared (FT-IR) spectroscopy, (1)H Nuclear Magnetic Resonance ((1)H NMR), X-ray powder diffraction (XRD), Ultraviolet-Visible (UV-Vis), and circular dichroism (CD) had confirmed a β-turn arrangement of PDB gelators and a semi-interpenetrating network (semi-IPN), which was formed through hydrogen bonds between LMWG fibers and polysaccharide chains. The evaluation of physicochemical properties of hydrogels indicates that gelator-polysaccharide hybrid hydrogels possess better mechanical and water retention properties than LMWG hydrogels.

A highly efficient self-assembly of responsive C(2) -cyclohexane-derived gelators.

The rational design and synthesis of a family of effective low-molecular-weight gelators (LMWGs) with a modular architecture based on a C(2) -1,4-diamide cyclohexane core are reported. Due to the high symmetry, the gelators are initially well distributed in solution and no trapped aggregates are formed before the assembly is triggered. The subsequent self-assembly process, which results in the formation of versatile gels, is highly efficient and can be triggered and tuned due to its remarkable dependence on the pH of solution.

Nanostructuring polymeric materials by templating strategies.

This contribution summarizes efforts in designing, assembling/synthesizing, and structurally and functionally characterizing nanostructured materials using anodized aluminum oxide (AAO) as a thin-film template. Optical waveguide spectroscopy, using a nanoporous template as the guiding structure, is a particularly powerful analytical tool. The layer-by-layer approach for the fabrication of multilayer assemblies is shown to allow the fabrication of nanotube arrays.