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To balance the requirements of transparency, mechanical strength, stable conductivity and biocompatibility of traditional electronic conductive hydrogels in intelligent devices is still a formidabl...

The sluggish nature of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) coupled with the high cost of related noble-metal catalysts stimulate the research of active non-noble met...

The in situ polymerization of monomers to form a second network within a preexisting network (first network) is a facile and effective strategy to fabricate semi-interpenetrating (semi-IPN) hydrogels with enhanced mechanical strength; while to comprehend the effects of the first polymer network on the polymerization process of the second network is still a challenging project. This paper introduces a simple method of employing dynamic rheological measurement loops to monitor the real time progress of the in situ polymerized acrylamide (AAm) in a chitosan (CS) solution towards the formation of a semi-IPN hydrogel. To identify the effects of the preexisting network on the polymerization gelation process, the concept “Effective Conversion Ratio (ECR)” is introduced to evaluate the first network effects on the requirement for the polymerized conversion ratio of the second network to form a critical gel. The rheological properties before gel point, at gel point, and at post-gel stage are discussed via the obtained real time data, respectively. The experimental results have proved the suitability of utilizing dynamic rheology to obtain the real time details of the semi-IPN gel fabrication process.

The effect of Fe-C alloy additions on thermal, mechanical and corrosive properties of (Cu50Zr40Ti10)1-x(Fe-C)x (x = 0–2.20 at%) alloys were systematically investigated. The results show that the Fe and C additions can enhance glass transition temperature Tg and onset crystallization temperature Tx, but narrow supercooled liquid region ΔTx. Work-hardening can be clearly observed for the Cu-based bulk metallic glasses (BMGs) containing Fe and C elements. The yield strength (σy), fracture strength (σf) and plastic strain (ep) are drastically increased by Fe-C alloy additions. The corrosion potential Ec increases and the corrosion current density ic decreases with increasing Fe and C contents. The studied Cu-based BMGs exhibit unique and novel anodic polarization behavior characterized by current platforms plus current serrations. The current serrations are much larger for the Cu-based BMGs with 0 ≤ x ≤ 1.32 at% than for those with 1.76 ≤ x ≤ 2.20 at%. The corrosion surface images are changed from the pits to the passive films by Fe-C alloy additions. The corrosion behavior gradually transforms from the pitting corrosion to the self-passivization with increasing Fe and C contents. The corresponding mechanisms are also discussed.

In vitro mimics recognized that the propensity of a negatively charged phospholipid, DPPS, monolayers to self-aggregate to three-dimensional (3D) giant folds under overcompression at an air–water interface. Time elapsing microscopical observations confirmed that such giant folds were able to float stably on the air–water interface for weeks or even longer. Ex situ atomic force microscopy (AFM) and transmission electronic microscopy (TEM) characterizations pointed out that such giant folds were composed of compactly stacked lipid layers. Phospholipase A2 (PLA2), a principal bactericide in human and animal tear secretion, was chosen to drive the in situ lipid giant folds disassembly on water and supported substrate surfaces, respectively. Our experimental results confirmed the layer-by-layer structures of the giant folds. It is noteworthy that the defect-rich areas of the giant lipid folds were eliminated quickly by PLA2 while defect-free lipid zones were left untouched, suggesting that PLA2 may serve as a ...

Hydrogels have been widely applied in the fields of biology, medicine, soft materials and flexible/wearable devices owing to their superior biocompatibility and their versatile physicochemical properties. Although multiple chemical and physical methods have been proposed to functionalize hydrogels, endowing hydrogels with multi-properties/functionalities utilizing few components is still a challenge. This paper describes a simple and effective method to functionalize polymeric hydrogels with carboxymethyl cellulose (CMC) modified Fe3O4 nanoparticles (CMC@Fe3O4 NPs). The as-prepared metallogels exhibit good self-healing ability, ionic conductivity, photo-thermal transformability and magnetic field responsiveness. A triple functional sensor was built up to prove the universal viability of this metallogel toward functional devices.

The field of intestinal biology is thirstily searching for different culture methods that complement the limitations of organoids, particularly the lack of a differentiated intestinal compartment. While being recognized as an important milestone for basic and translational biological studies, many primary cultures of intestinal epithelium (IE) rely on empirical trials using hydrogels of various stiffness, whose mechanical impact on epithelial organization remains vague until now. Here, we report the development of hydrogel scaffolds with a range of elasticities and their influence on IE expansion, organization, and differentiation. On stiff substrates (>5kPa), mouse IE cells adopt a flat cell shape and detach in the short-term. In contrast, on soft substrates (80–500Pa), they sustain for a long-term, pack into high density, develop columnar shape with improved apical-basal polarity and differentiation marker expression, a phenotype reminiscent of features invivomouse IE. We then developed a soft gel molding process to produce 3D Matrigel scaffolds of close-to-nature stiffness, which support and maintain a culture of mouse IE into crypt-villus architecture. Thus, the present work is up-to-date informative for the design of biomaterials forex vivointestinal models, offering self-renewalin vitroculture that emulates the mouse IE.

This paper demonstrates a rational protocol for the synthesis of ultrasmall bimetallic alloy nanoparticles (FeCo, FeNi, and NiCo

A facile one-step strategy for anchoring defective CoNx single clusters on partly reduced graphene oxide (RGO) is constructed to significantly improve the catalytic performance of non-noble metal complexes toward oxygen reduction reaction (ORR). Sequent loading with trace amounts of metal-free porphyrin and Co2+ in RGO can dramatically enhance both the half-wave potential and the peak current density. Intriguingly, the RGO/P/2Co single cluster exhibits the best ORR catalytic performance with the half-wave potential of 0.834 V, extremely approaching that of commercial Pt/C (0.836 V). This half-wave potential surpasses most of the reported half-wave potentials of RGO supported non-noble metal ORR catalysts through low-temperature synthesis. Furthermore, the as-prepared RGO/P/2Co delivers a peak current density of 1.3 times higher than that of Pt/C at the same loading, together with a high mass activity of 2.76 A mgCo–1. During the durability test, a cathodic current loss less than 10% is recorded after 8000...

A tripeptide (β-AspFF) gelator was designed and synthesised using solid-phase peptide synthesis. The as-prepared gelator formed a stable and clear multi-responsive gel in toluene solution. Encapsulating the quantum dots with β-AspFF effectively increased stability and antioxidisation ability which are beneficial for optical identification.

(Zr54Al10.2Ni9.4Cu26.4)100−xTix (x = 0–0.5, at%) bulk metallic glasses were prepared by water-cooled copper suction casting method. The Ti microalloying effect on glass forming ability and physical and chemical properties of Zr54Al10.2Ni9.4Cu26.4 glass forming alloy were systematically investigated. The glass forming ability is the largest for the Zr-based alloy with 0.3 at% Ti. The glass transition temperature is decreased by the Ti addition, while the supercooled liquid region is broadened. Both strength and plasticity are significantly enhanced by the Ti addition. The yield strength and the fracture strength firstly increase and then decrease when the Ti content reaches up to 0.3 at%. The plastic strain and the fracture strain increase with increasing Ti content. In addition, the corrosion potential is slightly decreased by the Ti addition. The corrosion current density increases with increasing Ti content. The pitting corrosion becomes increasingly serious with increasing Ti content. The honeycomb corrossion structure can be clearly observed when the Ti content reaches up to 0.5 at%. The corresponding mechanisms are also discussed in detail.

The in situ hydrothermal mineralization for a mixture of graphene oxide (GO) and Co-responsive supramolecular hydrogels led to a hybrid graphene aerogel, doped with Co and N elements. The as-prepared aerogels exhibited a competitive half-wave potential (0.840 V, versus RHE) and peak current density (2.35 mA cm−2) to that of Pt/C (0.836 V, 2.23 mA cm−2, respectively). Furthermore, they demonstrated a significantly perfect catalytic efficiency (nearly 100% of 4e− ORR) toward the oxygen reduction reaction (ORR). Insight into the structural details of the hybrid aerogels indicates that the CoOX active sites anchored on the graphene matrix play a central role in the upgrading of the catalytic performance of graphene aerogels.

A facile strategy was developed to fabricate structure controllable microcrystals of ferrocene-based metal–organic (Fc-Ala-BCB) materials through evaporation-induced self-assembly. Two distinctive microcrystals, microrods and microtubes had been achieved by tuning the solvents during the self-assemblies. X-ray diffraction analysis was conducted on single crystals to investigate the packing mode of Fc-Ala-BCB molecules, which indicated the two crystals with the hexagonal system. Inheriting the aromaticity and chirality of ferrocenyl and l-Ala, this organic molecule self-assembled into a single-helix structure through intermolecule hydrogen bonds and π–π stacking. Theoretical analysis and stimulated computations were carried out to compare the surface energies of certain planes. Among those microcrystals, the microrods exhibited a higher chemical activity in catalyzing the decomposition of H2O2, due to the high-density atomic steps and kinks on the high energy surfaces. However, the hollow hexagonal tubes d...

This paper introduces a tripeptide (β-Asp-Phe-Phe, abbreviation β-AspFF) which can self-assemble into long nanofibrils in toluene solvent and further entangle to organogels. The nanofibrils of β-AspFF can serves as ligands to incorporate with Co(II) in the organogels. After being re-immersed into HFIP-H2O mixed solution (Volume Ratio, 1:1), the β-AspFF-Co(II) xerogel exhibited decent oxygen binding properties. Impressively, in comparing with β-AspFF-Co(II) complex, the β-AspFF-Co(II) xerogel proved to be a higher efficient catalyst for catalyzing cyclohexene oxidation reaction. We therefore suppose that the porous and nanofibrils structure of the xerogel plays a key role to improve the catalytic behavior of β-AspFF-Co(II) complex.

(Zr53Al11.6Ni11.7Cu23.7)1-x(Fe77.1C22.9)x (x = 0–2.2 at.%) bulk metallic glasses (BMGs) were prepared by water cooling copper mold suction casting and their isochronous crystallization characteristics are investigated. The glass transition temperature, crystallization temperature, and crystallization peak temperature for all studied Zr-based BMGs firstly increase with increasing heating rate, and then decrease when the heating rate increases up to 60 K/min for the BMGs (0 ≤ x ≤ 0.88 at.%) and 80 K/min for the BMGs (1.32 ≤ x ≤ 2.20 at.%). The glass transition temperature, crystallization temperature, glass transition activiation energy, crystallization activiation energy, and activiation energy for crystallization peak temperature of the Fe- and C-free Zr-based BMG are the smallest among the studied BMGs, indicating that Fe and C additions are benificial to delaying the glass transition and the crystallization. Fe and C additions influence more significantly on the glass transition than on the crystallization. The local crystallization activiation energy for the Fe- and C-free BMG are the smallest among the studied BMGs, indicating that the crystallization is easy for the Fe- and C-free BMG. The peak height of local Avrami exponent and its corresponding crystallization fraction decrease with increasing heating rate except for the BMG (x = 1.32 at.%). The fragility indexes are 32–48 for the studied Zr-based BMGs. The present results are of guiding significance for preparing the excellent BMG composites by heat treatment and selecting suitable conditions for forming the BMGs.

Self-assembling natural drug hydrogels formed without structural modification and able to act as carriers are of interest for biomedical applications. A lack of knowledge about natural drug gels limits there current application. Here, we report on rhein, a herbal natural product, which is directly self-assembled into hydrogels through noncovalent interactions. This hydrogel shows excellent stability, sustained release and reversible stimuli-responses. The hydrogel consists of a three-dimensional nanofiber network that prevents premature degradation. Moreover, it easily enters cells and binds to toll-like receptor 4. This enables rhein hydrogels to significantly dephosphorylate IκBα, inhibiting the nuclear translocation of p65 at the NFκB signalling pathway in lipopolysaccharide-induced BV2 microglia. Subsequently, rhein hydrogels alleviate neuroinflammation with a long-lasting effect and little cytotoxicity compared to the equivalent free-drug in vitro. This study highlights a direct self-assembly hydrogel from natural small molecule as a promising neuroinflammatory therapy., There is interest in the development of drug-based hydrogels for responsive sustained drug release. Here, the authors report on the self-assembly of natural small molecule, rhein, into hydrogels and the application of the hydrogels as stable controlled release agents for neuro-inflammatory therapy

The growth mode of m-plane AlN crystal grown by physical vapor transport method is studied. The m-plane AlN crystal fabricated by spontaneous nucleation was used as a seed to grow bulk crystal, and 3-mm thick AlN crystals with a maximum lateral dimension of 20 mm were obtained. The Raman tensor elements of A1(TO), E2(high) and E1(TO) Raman models from the m-plane AlN crystal are investigated by angle-dependent polarized Raman scattering. The Raman tensor comparing with our previous report indicates the possible enhancement of the Raman tensor in the directions vertical to [0002] direction at higher growth temperature.

Introducing metal components into gel matrices provides an effective strategy to develop soft materials with advantageous properties such as: optical activity, conductivity, magnetic response activity, self-healing activity, catalytic activity, etc. In this context, a thorough overview of application-oriented metallogels is provided. Considering that many well-established metallogels start from serendipitous discoveries, insights into the structure-gelation relationship will offer a profound impact on the development of metallogels. Initially, design strategies for discovering new metallogels are discussed, then the advanced applications of metallogels are summarized. Finally, perspectives regarding the design of metallogels, the potential applications of metallogels and their derivative materials are briefly proposed.

Self-assembling natural drug hydrogels formed without structural modification and able to act as carriers are of interest for biomedical applications. A lack of knowledge about natural drug gels limits there current application. Here, we report on rhein, a herbal natural product, which is directly self-assembled into hydrogels through noncovalent interactions. This hydrogel shows excellent stability, sustained release and reversible stimuli-responses. The hydrogel consists of a three-dimensional nanofiber network that prevents premature degradation. Moreover, it easily enters cells and binds to toll-like receptor 4. This enables rhein hydrogels to significantly dephosphorylate IκBα, inhibiting the nuclear translocation of p65 at the NFκB signalling pathway in lipopolysaccharide-induced BV2 microglia. Subsequently, rhein hydrogels alleviate neuroinflammation with a long-lasting effect and little cytotoxicity compared to the equivalent free-drug in vitro. This study highlights a direct self-assembly hydrogel from natural small molecule as a promising neuroinflammatory therapy.

This paper introduces a new metallohydrogel precursor that offers a peculiar gelation response to Co2+ at pH 7–8. It is notable that the stability of this metallohydrogel is significantly dependent on its enantiomeric purity. In addition to the expected multi-stimuli responsive properties, including thixotropy, as well as re-assembly properties on adding HCl, this metallohydrogel possesses excellent self-healing behavior, which is uncommon in low-molecular-weight gelators. Electron microscopy (EM) studies revealed that the cryodried remains of this gel presented as well an organized three dimensional (3D) network of fibrils. This interesting metallohydrogel shows potential for developing new soft materials with drug delivery and catalysis properties.

A novel Pb2+-specific metallohydrogel HAIP–Pb was synthesized. HAIP–Pb possesses multi-stimuli responsiveness, including to pH, temperature, etc. Various measurements were performed to gain insights into the mechanism of gelation. The HAIP gelator can gel Pb2+ and simultaneously adsorb toxic dyes. Intriguingly, HAIP can cause gelation of soil containing Pb2+ ions.

The in situ hydrothermal mineralization for a mixture of graphene oxide (GO) and Co-responsive supramolecular hydrogels led to a hybrid graphene aerogel, doped with Co and N elements. The as-prepared aerogels exhibited a competitive half-wave potential (0.840 V, versus RHE) and peak current density (2.35 mA cm

A series of small molecular weight organogelators have been synthesized and studied. One as prepared organogel, named BDOT (n = 10) has exhibited excellent adsorption rate (97%) toward high concentrated mercury ions (0.01 M) from aqueous solution. The gelator itself can also serve as in situ colorimetric chemo sensor of Hg2+ hereinto.

Powders of two-phase B2/L21 Fe30Ni20Mn20Al30 (in at.%) were mechanically milled, and both as-milled powders and powders annealed at 823 K were examined using a combination of X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. The as-milled powder consisted of B2 (ordered b.c.c.) phases, whereas after a short anneal at 823 K β-Mn-structured precipitates were present and recrystallized B2 grains were observed in a L21 matrix. The longer the milling time, the finer the resulting powder size and the shorter the annealing time before precipitation occurred. The latter behavior is believed to be associated with nucleation occurring on dislocations formed during milling.

The effects of directional solidification (DS) processing on the microstructure and hardness of Fe 35 Ni 15 Mn 25 Al 25 are examined. The microstructure consists of (Fe, Mn)-enriched B2-ordered (ordered b.c.c.) and (Ni, Al)-enriched L2 1 -ordered (Heusler) phases aligned along directions in a complex percolating morphology. Because of the slow cooling rate during DS processing, the phase size in the DS alloy was approximately 3 times greater than that of an arc-melted alloy. Precipitates were found within both phases of the as-DS alloy, but not in the as-arc-melted alloy. Upon annealing, the phase size increased but with no significant change in the composition of the phases, while the interphase interfaces appeared to become sharper. The hardness of the DS alloy increased monotonically upon annealing, and showed an inverse relationship with the phase size before the formation of large β–Mn-structured precipitates. Several theoretical models are considered that might explain this variation of hardness with phase width. Longer annealing resulted in growth of the β–Mn-structured precipitates, causing a further 50% hardness increase.

Two novel multi-responsive metallohydrogels, namely, 2-PF–Ni and 3-PF–Ni, were successfully constructed from phenylalanine derivatives. The 2-PF gelator shows specific responses to Ni2+; particularly, 2-PF–Ni is lavender colored, which has been rarely reported among hydrogels triggered by Ni2+. 3-PF–Ni is light green and exhibits perfect thixotropy. This paper provides insights into the gelation mechanisms of these two metallogels.

We serendipitously discovered that the tripeptide Asp–Phe–Phe trifluoroacetic acid salt (hereafter abbreviated as β-AspFF) formed a reversible thermotropic gel in chloroform solution (at temperatures higher than the boiling point of chloroform) and a stable gel in toluene solution (at equal to or lower than the room temperature). Experimental results indicate that doping metal ions into β-AspFF toluene gels can trigger morphological variations in the gel skeleton, thereby increasing gel volume and inducing the collapse of organogels. Investigation on the cation-tuned gelation behavior of β-AspFF can be used to elucidate heating-induced gel collapse (of normal gel) or reverse thermotropic gelation as well as select carbamide and acetamide as activators of β-AspFF gels in chloroform solution at room temperature.

Cooling rate-induced softening in Y-based metallic glasses were verified in this work. By varying the speed of the roller in the melt-spinning process, it is found the hardness of the ribbon decrease with the cooling rate. Nanoindentation test also indicated that the ribbon at a higher cooling rate shows higher deformation energy. Contrary to crystalline materials, whose hardness usually increases with the cooling rate, the softening of metallic glasses is attributed to high concentration of defects frozen by fast cooling, and thus more structural relaxation during deformation.

Physical vapor transport (PVT) is the most successful and widely used approach for bulk aluminum nitride (AlN) single crystals. During the process of PVT growing AlN crystals, crucible materials, the growth setup, and the growth parameters (e.g., temperature distribution, growth pressure) are crucial. This work proposes a detailed study on the PVT growth of single AlN crystals with sizes ranging from nanometers to centimeters. AlN crystals with different sizes are grown by spontaneous nucleation. Furthermore, it discusses and contrasts the growth conditions and mechanisms of AlN crystals with different sizes. The structural and optical properties of the AlN crystals are also involved.

Correction for 'A Co(2+)-selective and chirality-sensitive supermolecular metallohydrogel with a nanofiber network skeleton' by Xiaojuan Wang et al., Nanoscale, 2016, DOI: 10.1039/c6nr00822d.