High power density output and durability of microbial fuel cells enabled by dispersed cobalt nanoparticles on nitrogen-doped carbon as the cathode electrocatalyst.

To endow microbial fuel cells (MFCs) with low cost, long-term stability and high-power output, a novel cobalt-based cathode electrocatalyst (Nano-Co@NC) is synthesized from a polygonal metal-organic framework ZIF-67. After calcining the resultant ZIF-67, the as-synthesized Nano-Co@NC is characteristic of cobalt nanoparticles (Nano-Co) embedded in nitrogen-doped carbon (NC) that inherits the morphology of ZIF-67 with a large surface area. The Nano-Co particles that are highly dispersed and firmly fixed on NC not only ensure electrocatalytic activity of Nano-Co@NC toward the oxygen reduction reaction on the cathode, but also inhibit the growth of non-electrogenic bacteria on the anode. Consequently, the MFC using Nano-Co@NC as the cathode electrocatalyst demonstrates excellent performance, delivering a comparable initial power density and exhibiting far better durability than that using Pt/C (20 wt%) as the cathode electrocatalyst. The low cost and the excellent performance of Nano-Co@NC make it promising for MFCs to be used in practice.

A facile synthesis of FeS/Fe3C nanoparticles highly dispersed on in situ grown N-doped CNTs as cathode electrocatalysts for microbial fuel cells.

A novel composite of iron sulfide, iron carbide and nitrogen carbides (Nano-FeS/Fe3C@NCNTs) as a cathode electrocatalyst for microbial fuel cells (MFCs) is synthesized by a one-pot solid state reaction, which yields a unique configuration of FeS/Fe3C nanoparticles highly dispersed on in situ grown nitrogen-doped carbon nanotubes (NCNTs). The highly dispersed FeS/Fe3C nanoparticles possess large active sites, while the NCNTs provide an electronically conductive network. Consequently, the resultant Nano-FeS/Fe3C@NCNTs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), with a half-wave potential close to that of Pt/C (about 0.88 V vs. RHE), and enable MFCs to deliver a power density of 1.28 W m-2 after two weeks' operation, which is higher than that of MFCs with Pt/C as the cathode electrocatalyst (1.02 W m-2). Theoretical calculations and experimental data demonstrate that there is a synergistic effect between Fe3C and FeS in Nano-FeS/Fe3C@NCNTs. Fe3C presents a strong attraction and electron-donating tendency to oxygen molecules, serving as the main active component, while FeS reduces charge transfer resistance by transferring electrons to Fe3C, synergistically improving the kinetics of the ORR and power density of MFCs.

Bioinspired conductive cellulose liquid-crystal hydrogels as multifunctional electrical skins.

Bionic electronic skin (E-skin) that could convert external physical or mechanical stimuli into output signals has a wide range of applications including wearable devices, artificial prostheses, software robots, etc. Here, we present a chameleon-inspired multifunctional E-skin based on hydroxypropyl cellulose (HPC), Poly(Acrylamide-co-Acrylic acid) (PACA), and carbon nanotubes (CNTs) composited liquid-crystal hydrogel. We found that the HPC could still form cholesteric liquid-crystal photonic structures with the CNTs additive for enhancing their color saturation and PACA polymerization for locating their assembled periodic structures. As the composite hydrogel containing HPC elements and the PACA scaffold responds to different stimuli, such as temperature variations, mechanical pressure, and tension, it could correspondingly change its volume or internal nanostructure and report these as visible color switches. In addition, due to the additive of CNTs, the composite hydrogel could also output these stimuli as electrical resistance signals. Thus, the hydrogel E-skins had the ability of quantitatively feeding back external stimuli through electrical resistance as well as visually mapping the stimulating sites by color variation. This dual-signal sensing provides the ability of visible-user interaction as well as antiinterference, endowing the multifunctional E-skin with great application prospects.

A triple-diazonium reagent for virus crosslinking and the synthesis of an azo-linked molecular cage.

The first bench-stable triple-diazonium reagent (TDA-1) was rationally designed and synthesized for coupling and crosslinking. The three reactive sites of TDA-1 can react with phenol-containing molecules as well as plant viruses in aqueous buffers efficiently. In addition, a new-type azo-linked cage was constructed by the direct reaction of TDA-1 with a triple-phenol molecule and was characterized by X-ray crystallography.

Tailoring conductive inverse opal films with anisotropic elliptical porous patterns for nerve cell orientation.

BACKGROUND: The nervous system is critical to the operation of various organs and systems, while novel methods with designable neural induction remain to exploit. RESULTS: Here, we present a conductive inverse opal film with anisotropic elliptical porous patterns for nerve orientation induction. The films are fabricated based on polystyrene (PS) inverse opal scaffolds with periodical elliptical porous structure and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) mixed polyacrylamide (PAAm) polymers fillers. It is demonstrated that the anisotropic elliptical surface topography allows the nerve cells to be induced into orientation connected with the stretching direction. Because of the anisotropic features of the film which can be stretched into different directions, nerve cells can be induced to grow in one or two directions, forming a neural network and promoting the connection of nerve cells. It is worth mentioning that the PEDOT:PSS-doped PAAm hydrogels endow the film with conductive properties, which makes the composite films be a suitable candidate for neurites growth and differentiation. CONCLUSIONS: All these features of the conductive and anisotropic inverse opal films imply their great prospects in biomedical applications.

Topographically Conductive Butterfly Wing Substrates for Directed Spiral Ganglion Neuron Growth.

Spiral ganglion neuron (SGN) degeneration can lead to severe hearing loss, and the directional regeneration of SGNs has shown great potential for improving the efficacy of auditory therapy. Here, a novel 3D conductive microstructure with surface topologies is presented by integrating superaligned carbon-nanotube sheets (SA-CNTs) onto Morpho Menelaus butterfly wings for SGN culture. The parallel groove-like topological structures of M. Menelaus wings induce the cultured cells to grow along the direction of its ridges. The excellent conductivity of SA-CNTs significantly improves the efficiency of cellular information conduction. When integrating the SA-CNTs with M. Menelaus wings, the SA-CNTs are aligned in parallel with the M. Menelaus ridges, which further strengthens the consistency of the surface topography in the composite substrate. The SA-CNTs integrated onto butterfly wings provide powerful physical signals and regulate the behavior of SGNs, including cell survival, adhesion, neurite outgrowth, and synapse formation. These features indicate the possibility of directed regeneration after auditory nerve injury.

Biohybrid robotics with living cell actuation.

As simulators of organisms in Nature, soft robots have been developed over the past few decades. In particular, biohybrid robots constructed by integrating living cells with soft materials demonstrate the unique advantage of simulating the construction and functions of human tissues or organs, thus attracting extensive attention and research interest. Here, we present up-to-date studies concerning biohybrid robots with various biological actuators such as contractile cells and microorganisms. After presenting the basic components including biological components and synthetic materials, the controlling methods and locomotion modalities of biohybrid robots are clarified and summarized. We then focus on the applications, especially the biomedical applications, of the biohybrid robots including drug delivery, bioimaging, and tissue engineering. The challenges and prospects for the future development of biohybrid robots are also presented.

Bio-inspired self-healing structural color hydrogel.

Biologically inspired self-healing structural color hydrogels were developed by adding a glucose oxidase (GOX)- and catalase (CAT)-filled glutaraldehyde cross-linked BSA hydrogel into methacrylated gelatin (GelMA) inverse opal scaffolds. The composite hydrogel materials with the polymerized GelMA scaffold could maintain the stability of an inverse opal structure and its resultant structural colors, whereas the protein hydrogel filler could impart self-healing capability through the reversible covalent attachment of glutaraldehyde to lysine residues of BSA and enzyme additives. A series of unprecedented structural color materials could be created by assembling and healing the elements of the composite hydrogel. In addition, as both the GelMA and the protein hydrogels were derived from organisms, the composite materials presented high biocompatibility and plasticity. These features of self-healing structural color hydrogels make them excellent functional materials for different applications.

A Fast-Response Red Shifted Fluorescent Probe for Detection of H2S in Living Cells.

Near-infrared (NIR) fluorescent probes are attractive tools for bioimaging applications because of their low auto-fluorescence interference, minimal damage to living samples, and deep tissue penetration. H2S is a gaseous signaling molecule that is involved in redox homeostasis and numerous biological processes in vivo. To this end, we have developed a new red shifted fluorescent probe 1 to detect physiological H2S in live cells. The probe 1 is based on a rhodamine derivative as the red shifted fluorophore and the thiolysis of 7-nitro 1,2,3-benzoxadiazole (NBD) amine as the H2S receptor. The probe 1 displays fast fluorescent enhancement at 660 nm (about 10-fold turn-ons, k2 = 29.8 M-1s-1) after reacting with H2S in buffer (pH 7.4), and the fluorescence quantum yield of the activated red shifted product can reach 0.29. The probe 1 also exhibits high selectivity and sensitivity towards H2S. Moreover, 1 is cell-membrane-permeable and mitochondria-targeting, and can be used for imaging of endogenous H2S in living cells. We believe that this red shifted fluorescent probe can be a useful tool for studies of H2S biology.

Photocontrolled Healable Structural Color Hydrogels.

Structural color hydrogels with healable capability are of great significance in many fields, however the controllability of these materials still needs optimizing. Thus, this work presents a healable structural color hydrogel with photocontrolling properties. The component parts of the hydrogel are a graphene oxide (GO) integrated inverse opal hydrogel scaffold and a hydrogel filler with reversible phase transition. The inverse opal scaffold provides stable photonic crystal structure and the hydrogel filler is the foundation of healing. Taking advantage of the prominent photothermal conversion efficiency of GO, the healable structural color material is imparted with photocontrolled properties. It is found that the structural color hydrogel shaped in complex patterns can heal under near-infrared (NIR) irradiation. These features indicate that the optical controllable healable structural color hydrogel can be employed in various applications, such as constructing complex objects, repairing tissues, and so on.

Droplet Microarray on Patterned Butterfly Wing Surfaces for Cell Spheroid Culture.

Three-dimensional (3D) cell spheroids have a demonstrated value for in vitro biological research and therapeutics development. Attempts to this technique focus on the development of effective methods for fabricating cell spheroids. Here, inspired by the heterogeneously textured wettability bumps (with hydrophilic peaks and hydrophobic bases) of Stenocara beetle, we present a biotemplated substrate with wettable hydrogel arrays for culturing the cell spheroids. The biotemplates were Morpho butterfly wings with chitin and protein components, which could provide a natural superhydrophobic surface without any modification. The droplet microarrays could be formed for cell spheroid culture on this bioinspired wing substrate by using the hydrogel patterns to hanging droplets. The hanging drop culture method on hydrogel-covered wings has the advantages of high speed, uniform size, and controllable diameter for the formation of 3D cell spheroids. It was demonstrated that drugs produced distinct responses in the 3D cell spheroids compared to conventional two-dimensional cell cultures. As the presented system does not require complex instruments and chemical modifications, our method can simply construct the desired wettability substrates with high biocompatibility for cell culture, drug testing, and other biomedical applications.

Cuttlefish Ink Tagged Photonic Crystal Particles and Their Ion-Responsive Construction.

Colloidal crystal materials have potential values in coding, sensing, displaying and so on. Attempts to promote these values tend to focus on the development of functional colloidal crystal materials with high color saturations and bright structural colors for practical applications. Thus, this work presented novel cuttlefish ink nanoparticles doped colloidal crystal particle material, which had distinguishable and high saturation colors, and could response to the electric field and pH obviously. It was also found that the doping could result in a short-range order and long-range disorder structure of the colloidal crystals, which endowed them with wide viewing angles. More importantly, by using electric field and ions dual-responsive hydrogel to replicate the composite colloidal crystals particles, the resultant cuttlefish ink nanoparticles doped inverse opal particles were imparted with the same high saturation vivid structural colors, as well as obviously structural color tunability. These features make the cuttlefish ink nanoparticles doped colloidal crystal particles ideal for many practical applications where structural color materials is needed.

Effect of target animacy on hand preference in Sichuan snub-nosed monkeys (Rhinopithecus roxellana).

Twenty-eight captive Sichuan snub-nosed monkeys (Rhinopithecus roxellana) were involved in the current study. Many individuals showed handedness, with a modest tendency toward left-hand use especially for animate targets, although no group-level handedness was found. There was no significant gender difference in the direction and strength of hand preference for both targets. Females showed a significantly higher overall rate of actions toward animate targets than inanimate targets for both hands, whereas males displayed almost the reversed pattern. There were no significant interactions between lateral hand use and target animacy for either males or females. Most individuals showed rightward or leftward laterality shift trends between inanimate and animate targets. These findings to some extent support the existence of a potential trend concerning a categorical neural distinction between targets demanding functional manipulation (inanimate objects) and those demanding social manipulation (animate objects), even though specialized hand preference based on target animacy has not been fully established in this arboreal Old World monkey species.

Bone-derived extracellular matrix hydrogel from thrombospondin-2 knock-out mice for bone repair.

Bone extracellular matrix (ECM) has been shown to mimic aspects of the tissue's complex microenvironment, suggesting its potential role in promoting bone repair. However, current ECM-based therapies suffer from limitations such as inefficient scale-up, lack of mechanical integrity, and sub-optimal efficacy. Here, we fabricated hydrogels from decellularized ECM (dECM) from wild type (WT) and thrombospondin-2 knock-out (TSP2KO) mouse bones. TSP2KO bone ECM hydrogel was found to have distinct mechanical properties and collagen fibril assembly from WT. Furthermore, TSP2KO hydrogel promoted mesenchymal stem cell (MSC) attachment, spreading, and invasion in vitro. Similarly, it promoted formation of tube-like structures by human umbilical vein endothelial cells (HUVECs). When applied to a murine calvarial defect model, TSP2KO hydrogel enhanced repair, in part, due to increased angiogenesis. Our study suggests the pro-angiogenic therapeutic potential of TSP2KO bone ECM hydrogel in bone repair. STATEMENT OF SIGNIFICANCE: The study describes the first successful preparation of a novel hydrogel made from decellularized bones from wild-type mice and mice lacking thrombospondin-2 (TSP2). Hydrogels from TSP2 knock-out (TSP2KO) bones have unique characteristics in structure and biomechanics. These gels interacted well with cells in vitro and helped repair damaged bone in a mouse model. Therefore, TSP2KO bone-derived hydrogel has translational potential for accelerating repair of bone defects that are otherwise difficult to heal. This study not only creates a new material with promise for accelerated healing, but also validates tunability of native biomaterials by genetic engineering.

Novel muscle-derived extracellular matrix hydrogel promotes angiogenesis and neurogenesis in volumetric muscle loss.

Volumetric muscle loss (VML) represents a clinical challenge due to the limited regenerative capacity of skeletal muscle. Most often, it results in scar tissue formation and loss of function, which cannot be prevented by current therapies. Decellularized extracellular matrix (DEM) has emerged as a native biomaterial for the enhancement of tissue repair. Here, we report the generation and characterization of hydrogels derived from DEM prepared from WT or thrombospondin (TSP)-2 null muscle tissue. TSP2-null hydrogels, when compared to WT, displayed altered architecture, protein composition, and biomechanical properties and allowed enhanced invasion of C2C12 myocytes and chord formation by endothelial cells. They also displayed enhanced cell invasion, innervation, and angiogenesis following subcutaneous implantation. To evaluate their regenerative capacity, WT or TSP2 null hydrogels were used to treat VML injury to tibialis anterior muscles and the latter induced greater recruitment of repair cells, innervation, and blood vessel formation and reduced inflammation. Taken together, these observations indicate that TSP2-null hydrogels enhance angiogenesis and promote muscle repair in a VML model.

Efficacy of a modified twin block appliance compared with the traditional twin block appliance in children with hyperdivergent mandibular retrognathia: protocol for a single-centre, single-blind, randomised controlled trial.

INTRODUCTION: Compensatory mouth breathing, caused by nasopharyngeal obstructive diseases, is the main cause of hyperdivergent mandibular retrognathia in children. Such deformities require effective growth guidance before pubertal growth peaks. The traditional mandibular advancement device, twin block (TB), can guide the forward development of the mandible. However, the side effect of increasing the vertical dimension of the lower facial third, worsens the facial profile of children with divergent growth trends. To solve this problem, a modified TB (LLTB) appliance was designed to control the vertical dimension by intruding incisors and inhibiting the elongation of posterior teeth during the advancement of the mandible, which could avoid the side effects of traditional appliances and effectively guide the growth of the mandible in a normal direction. METHODS AND ANALYSIS: The study was designed as a single-centre, single-blind, randomised, parallel controlled trial. We aim to enrol 60 children aged 9-14 years with hyperdivergent skeletal class II malocclusion, using a 1:1 allocation ratio. The participants were will be randomly assigned to receive either the TB or LLTB treatment. The primary outcome will be a change in the angle of the mandibular plane relative to the anterior cranial base. The secondary outcomes will include changes in the sagittal maxillomandibular relation, occlusal plane, facial height, morphology of the mandible and upper airway width. Safety endpoints will also be evaluated. ETHICS AND DISSEMINATION: Ethical approval was obtained from the ethics committee of Shanghai Stomatological Hospital. Both participants and their guardians will be fully informed of the study and sign an informed consent form before participating in the trial. The results will be publicly available in peer-reviewed scientific journals. TRIAL REGISTRATION NUMBER: ChiCTR2000035882.

Injectable TG-linked recombinant human collagen hydrogel loaded with bFGF for rat cranial defect repair.

The basic fibroblast growth factor (bFGF) plays a significant role in promoting the process of bone repair, but bFGF cannot keep its biological activity stable under normal physiological conditions. Therefore, the development of better biomaterials to carry bFGF remains a challenge for bone repair and regeneration. Here we designed a novel recombinant human collagen (rhCol), which could be cross-linked by transglutaminase (TG) and loaded bFGF to prepare rhCol/bFGF hydrogels. The rhCol hydrogel possessed a porous structure and good mechanical properties. The assays, including cell proliferation, migration, and adhesion assay, were performed to evaluate the biocompatibility of rhCol/bFGF and the results demonstrated that the rhCol/bFGF promoted cell proliferation, migration and adhesion. The rhCol/bFGF hydrogel degraded and released bFGF controllably, enhancing utilization rate of bFGF and allowing osteoinductive activity. The results of RT-qPCR and immunofluorescence staining also proved that rhCol/bFGF promoted expression of bone-related proteins. The rhCol/bFGF hydrogels were applied in the cranial defect in rats and the results confirmed that it accelerates bone defect repair. In conclusion, rhCol/bFGF hydrogel has excellent biomechanical properties and can continuously release bFGF to promote bone regeneration, suggesting that rhCol/bFGF hydrogel is a potential scaffold in clinic application.

Phylogenetic and Taxonomic Analyses of Three New Wood-Inhabiting Fungi of Xylodon (Basidiomycota) in a Forest Ecological System.

Wood-inhabiting fungi are a cosmopolitan group and show a rich diversity, growing in the vegetation of boreal, temperate, subtropical, and tropical regions. Xylodon grandineus, X. punctus, and X. wenshanensis spp. nov. were found in the Yunnan-Guizhou Plateau, China, suggested here to be new fungal species in light of their morphology and phylogeny. Xylodon grandineus is characterized by a grandinioid hymenophore and ellipsoid basidiospores; X. punctus has a membranous hymenophore, a smooth hymenial surface with a speckled distribution, and absent cystidia; X. wenshanensis has a grandinioid hymenophore with a cream to slightly buff hymenial surface and cystidia of two types. Sequences of the ITS and nLSU rRNA markers of the studied samples were generated, and phylogenetic analyses were performed using the maximum likelihood, maximum parsimony, and Bayesian inference methods. After a series of phylogenetic studies, the ITS+nLSU analysis of the order Hymenochaetales indicated that, at the generic level, six genera (i.e., Fasciodontia, Hastodontia, Hyphodontia, Lyomyces, Kneiffiella, and Xylodon) should be accepted to accommodate the members of Hyphodontia sensu lato. According to a further analysis of the ITS dataset, X. grandineus was retrieved as a sister to X. nesporii; X. punctus formed a monophyletic lineage and then grouped with X. filicinus, X. hastifer, X. hyphodontinus, and X. tropicus; and X. wenshanensis was a sister to X. xinpingensis.

Electroconductive and Anisotropic Structural Color Hydrogels for Visual Heart-on-a-Chip Construction.

Heart-on-a-chip plays an important role in revealing the biological mechanism and developing new drugs for cardiomyopathy. Tremendous efforts have been devoted to developing heart-on-a-chip systems featuring simplified fabrication, accurate imitation and microphysiological visuality. In this paper, the authors present a novel electroconductive and anisotropic structural color hydrogel by simply polymerizing non-close-packed colloidal arrays on super aligned carbon nanotube sheets (SACNTs) for visualized and accurate heart-on-a-chip construction. The generated anisotropic hydrogel consists of a colloidal array-locked hydrogel layer with brilliant structural color on one surface and a conductive methacrylated gelatin (GelMA)/SACNTs film on the other surface. It is demonstrated that the anisotropic morphology of the SACNTs could effectively induce the alignment of cardiomyocytes, and the conductivity of SACNTs could contribute to the synchronous beating of cardiomyocytes. Such consistent beating rhythm caused the deformation of the hydrogel substrates and dynamic shifts in structural color and reflection spectra of the whole hybrid hydrogels. More attractively, with the integration of such cardiomyocyte-driven living structural color hydrogels and microfluidics, a visualized heart-on-a-chip system with more consistent beating frequency has been established for dynamic cardiomyocyte sensing and drug screening. The results indicate that the electroconductive and anisotropic structural color hydrogels are potential for various biomedical applications.

Advances in the development and optimization strategies of the hemostatic biomaterials.

Most injuries are accompanied by acute bleeding. Hemostasis is necessary to relieve pain and reduce mortality in these accidents. In recent years, the traditional hemostatic materials, including inorganic, protein-based, polysaccharide-based and synthetic materials have been widely used in the clinic. The most prominent of these are biodegradable collagen sponges (Helistat®, United States), gelatin sponges (Ethicon®, SURGIFOAM®, United States), chitosan (AllaQuixTM, ChitoSAMTM, United States), cellulose (Tabotamp®, SURGICEL®, United States), and the newly investigated extracellular matrix gels, etc. Although these materials have excellent hemostatic properties, they also have their advantages and disadvantages. In this review, the performance characteristics, hemostatic effects, applications and hemostatic mechanisms of various biomaterials mentioned above are presented, followed by several strategies to improve hemostasis, including modification of single materials, blending of multiple materials, design of self-assembled peptides and their hybrid materials. Finally, the exploration of more novel hemostatic biomaterials and relative coagulation mechanisms will be essential for future research on hemostatic methods.