A Cellulose/Chitosan Dual Cross-Linked Multifunctional and Resilient Hydrogel for Emergent Open Wound Management.

Adhesive hydrogel holds huge potential in biomedical applications, such as hemostasis and emergent wound management during outpatient treatment or surgery. However, most adhesive hydrogels underperform to offer robust adhesions on the wet tissue, increasing the risk of hemorrhage and reducing the fault tolerance of surgery. To address this issue, this work develops a polysaccharide-based bioadhesive hydrogel tape (ACAN) consisting of dual cross-linking of allyl cellulose (AC) and carboxymethyl chitosan (CMCS). The hygroscopicity of AC and CMCS networks enables ACAN to remove interfacial water from the tissue surface and initializes a physical cross-link instantly. Subsequently, covalent cross-links are developed with amine moieties to sustain long-term and robust adhesion. The dual cross-linked ACAN also has good cytocompatibility with controllable mechanical properties matching to the tissue, where the addition of CMCS provides remarkable antibacterial properties and hemostatic capability. Moreover, compared with commercially available 3 M film, ACAN provides an ultrafast wound healing on tissue. The ACAN hybrid hydrogels have advantages such as biocompatibility and antibacterial, hemostatic, and wound healing properties, shedding new light on first-aid tape design and advancing the cellulose-based materials technology for high-performance biomedical applications.

Vanillin Cross-Linked Chitosan Film with Controlled Release of Green Tea Polyphenols for Active Food Packaging.

We report a novel cross-linked chitosan composite film containing vanillin, glycerol, and green tea extract. The effects of vanillin-mediated cross-linking and the incorporation of antimicrobial green tea polyphenols were investigated. The cross-linking effect, confirmed by Fourier transform infrared (FTIR) analysis, increased the tensile strength of the biopolymer film to 20.9 ± 3 MPa. The release kinetics of polyphenols from the chitosan-vanillin matrix was studied, and we reported an initial burst release (8 h) followed by controlled release (8 to 400 h). It was found that both vanillin and green tea polyphenols were successful inhibitors of foodborne bacteria, with a minimum inhibitory concentration of the tea polyphenols determined as 0.15 mg/mL (Staphylococcus aureus). These active components also displayed strong antioxidant capacities, with polyphenols quenching >80% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals at all concentrations tested. Degradation results revealed that there was a significant (>85%) mass loss of all samples after being buried in compost for 12 weeks. The biopolymeric films, prepared by solvent casting methods, adhere to green chemistry and waste valorization principles. The one-pot recipe reported may also be applied to other cross-linkers and active compounds with similar chemical functionalities. Based on the obtained results, the presented material provides a promising starting point for the development of a degradable active packaging material.

Innovating fire safety with recombinant hydrophobic proteins for textile fire retardancy.

Fire retardancy for textiles is important to prevent the rapid spread of fire and minimize damage to property and harm to human life. To infer fire-resistance on textile materials such as cotton or nylon, chemical coatings are often used. These chemicals are usually toxic, and economically and environmentally unsustainable, however, some naturally produced protein-based fire retardants could be an alternative. A biofilm protein from Bacillus subtilis (BslA) was identified and recombinantly expressed in Escherichia coli with a double cellulose binding domain. It was then applied to a range of natural and synthetic fabric materials. A flame retardancy test found that use of BslA reduced fire damage by up to 51% and would pass fire retardancy testing according to British standards. It is therefore a viable and sustainable alternative to current industrial fire-retardant coatings.

A Simple and Effective Physical Ball-Milling Strategy to Prepare Super-Tough and Stretchable PVA@MXene@PPy Hydrogel for Flexible Capacitive Electronics.

Biomimetic flexible electronics for E-skin have received increasing attention, due to their ability to sense various movements. However, the development of smart skin-mimic material remains a challenge. Here, a simple and effective approach is reported to fabricate super-tough, stretchable, and self-healing conductive hydrogel consisting of polyvinyl alcohol (PVA), Ti3 C2 Tx MXene nanosheets, and polypyrrole (PPy) (PMP hydrogel). The MXene nanosheets and Fe3+ serve as multifunctional cross-linkers and effective stress transfer centers, to facilitate a considerable high conductivity, super toughness, and ultra-high stretchability (elongation up to 4300%) for the PMP hydrogel with. The hydrogels also exhibit rapid self-healing and repeatable self-adhesive capacity because of the presence of dynamic borate ester bond. The flexible capacitive strain sensor made by PMP hydrogel shows a relatively broad range of strain sensing (up to 400%), with a self-healing feature. The sensor can precisely monitor various human physiological signals, including joint movements, facial expressions, and pulse waves. The PMP hydrogel-based supercapacitor is demonstrated with a high capacitance retention of ≈92.83% and a coulombic efficiency of ≈100%.

Recent Advances in Sources of Bio-Inspiration and Materials for Robotics and Actuators.

Bionic robotics and actuators have made dramatic advancements in structural design, material preparation, and application owing to the richness of nature and innovative material design. Appropriate and ingenious sources of bio-inspiration can stimulate a large number of different bionic systems. After millennia of survival and evolutionary exploration, the mere existence of life confirms that nature is constantly moving in an evolutionary direction of optimization and improvement. To this end, bio-inspired robots and actuators can be constructed for the completion of a variety of artificial design instructions and requirements. In this article, the advances in bio-inspired materials for robotics and actuators with the sources of bio-inspiration are reviewed. The specific sources of inspiration in bionic systems and corresponding bio-inspired applications are summarized first. Then the basic functions of materials in bio-inspired robots and actuators is discussed. Moreover, a principle of matching biomaterials is creatively suggested. Furthermore, the implementation of biological information extraction is discussed, and the preparation methods of bionic materials are reclassified. Finally, the challenges and potential opportunities involved in finding sources of bio-inspiration and materials for robotics and actuators in the future is discussed.

Sustainable sepiolite-based composites for fast clotting and wound healing.

Uncontrolled bleeding and bacterial coinfection are the major causes of death after an injury. Fast hemostatic capacity, good biocompatibility, and bacterial coinfection inhibition pose great challenges to hemostatic agent development. A prospective sepiolite/Ag nanoparticles (sepiolite@AgNPs) composite has been prepared by using natural clay sepiolite as template. A tail vein hemorrhage mouse model and a rabbit hemorrhage model were used to evaluate the hemostatic properties of the composite. The sepiolite@AgNPs composite can quickly absorb fluid to subsequently stop bleeding due to the natural fibrous crystal structure of sepiolite, and inhibit bacterial growth with the antibacterial ability of AgNPs. Compared with commercially-available zeolite material, the as-prepared composite exhibits competitive hemostatic properties without exothermic reaction in the rabbit model of femoral and carotid artery injury. The rapid hemostatic effect was due to the efficient absorption of erythrocyte and activation of the coagulation cascade factors and platelets. Besides, after heat-treatment, the composites can be recycled without significant reduction of hemostatic performance. Our results also prove that sepiolite@AgNPs nanocomposites can stimulate wound healing. The sustainability, lower-cost, higher bioavailability, and stronger hemostatic efficacy of sepiolite@AgNPs composite render these nanocomposites as more favorable hemostatic agents for hemostasis and wound healing.

Biofilm inspired fabrication of functional bacterial cellulose through ex-situ and in-situ approaches.

Bacterial cellulose (BC) has been explored for use in a range of applications including tissue engineering and textiles. BC can be produced from waste streams, but sustainable approaches are needed for functionalisation. To this end, BslA, a B. subtilis biofilm protein was produced recombinantly with and without a cellulose binding module (CBM) and the cell free extract was used to treat BC either ex-situ, through drip coating or in-situ, by incorporating during fermentation. The results showed that ex-situ modified BC increased the hydrophobicity and water contact angle reached 120°. In-situ experiments led to a BC film morphological change and mechanical testing demonstrated that addition of BslA with CBM resulted in a stronger, more elastic material. This study presents a nature inspired approach to functionalise BC using a biofilm hydrophobin, and we demonstrate that recombinant proteins could be effective and sustainable molecules for functionalisation of BC materials.

Preparation of ultrathin carbon-coated CdS nanobelts for advanced Li and Na storage.

In this paper, we report a simple hydrothermal method for preparation of ultrathin carbon-coated CdS (CdS@C) nanobelts. The CdS@C nanobelts show superior electrochemical properties as an anode material for Li-ion batteries. The optimized CdS@C composites deliver a reversible capacity around 910 mAhg-1 and 48 mAhg-1 at 0.1 Ag-1 and 30.0 Ag-1, respectively. Moreover, the optimized nanobelts are also potential materials for Na storage. A stable capacity around 240 mAhg-1 is obtained at 0.1 Ag-1, even after 100 cycles.

Chitosan-based melatonin bilayer coating for maintaining quality of fresh-cut products.

This work was designed to develop the chitosan-based melatonin layer-by-layer assembly (CMLLA) via the inclusion method. The structural characterizations and interaction present in CMLLA were investigated by the scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier Transform-Infrared spectroscopy (FTIR). The ratio of chitosan (CH) to carboxymethylcellulose (CMC) greatly influenced the mechanical properties, including the tensile strength, moisture content and color performance. Results showed that both antioxidant and antimicrobial properties of CMLLA were enhanced with the addition of melatonin (MLT). Furthermore, it was demonstrated that the CMLLA with 1.2 % (w/v) CH, 0.8 % (w/v) CMC and 50 mg/L MLT better contributed to the delay of chlorophyll degradation and the maintenance of shelf-life quality. Results from this study might open up new insights into the approaches of quality improvement of postharvest fresh products by incorporating the natural antioxidant compounds into natural polymers.

Co-immobilization multienzyme nanoreactor with co-factor regeneration for conversion of CO2.

Multienzymatic conversion of carbon dioxide (CO2) into chemicals has been extensively studied. However, regeneration and reuse of co-factor are still the main problems for the efficient conversion of CO2. In this study, a nanoscale multienzyme reactor was constructed by encapsulating simultaneously carbonic anhydrase (CA), formate dehydrogenase (FateDH), co-factor (NADH), and glutamate dehydrogenases (GDH) into ZIF-8. In the multienzyme reactors, cationic polyelectrolyte (polyethyleneimine, PEI) was doped in the ZIF-8 by dissolving it in the precursors of ZIF-8. Co-factor (NADH) was anchored in ZIF-8 by ion exchange between PEI (positive charge) and co-factor (negative charge), and regenerated through GDH embedded in the ZIF-8, thus keeping high activity of FateDH. Activity recovery of FateDH in the multienzyme reactors reached 50%. Furthermore, the dissolution of CO2 in the reaction solution was increased significantly by the combination of CA and ZIF-8. As a result, the nanoscale multienzyme reactor exhibited superior capacity for conversion of CO2 to formate. Compared with free multienzyme system, formate yield was increased 4.6-fold by using the nanoscale multienzyme reactor. Furthermore, the nanoscale multienzyme reactor still retained 50% of its original productivity after 8 cycles, indicating excellent reusability.

Co9S8 nanoparticles embedded into amorphous carbon as anode materials for lithium-ion batteries.

In this paper, Co9S8 nanoparticles embedded into amorphous carbon have been synthesized by a simple electrospinning method followed by a high-temperature annealing process. The unique structure endows the Co9S8/C composites with excellent electrochemical properties. Co9S8 particles embedded into the carbon matrix show a high Li storage capacity around 1100 and 358 mAhg-1 at a current density of 0.1 and 5.0 Ag-1, respectively. After 200 cycles, an impressive discharge capacity of around 1063.4 mAhg-1 can be obtained at a current density of 0.3 Ag-1.

Solid-State, Low-Cost, and Green Synthesis and Robust Photochemical Hydrogen Evolution Performance of Ternary TiO2/MgTiO3/C Photocatalysts.

Solar-driven photochemical hydrogen evolution is a promising route to sustainable hydrogen fuel production. Large-scale preparation of highly active photocatalysts using elementally abundant and less-expensive materials is urgently required for widespread practical application. Here, we report a highly efficient and low-cost TiO2/MgTiO3/C heterostructure photocatalyst for photochemical water splitting, which was synthesized on gram scale via a facile mechanochemical method. The heterostructure and carbon sensitization offer excellent photoconversion efficiency as well as good photostability. Under irradiation of one AM 1.5G sunlight, the optimal TiO2/MgTiO3/C photocatalyst can show a great solar-driven hydrogen evolution rate (33.3 mmol·h-1·g-1), which is much higher than the best yields ever reported for MgTiO3-related photocatalysts or pure TiO2 (P-25). We hope this work will attract more attention to inspire further work by others for the development of low-cost, efficient, and robust photocatalysts for producing hydrogen in artificial photosynthetic systems.

Hierarchical C/SiO x /TiO2 ultrathin nanobelts as anode materials for advanced lithium ion batteries.

TiO2-based nanomaterials are demonstrated to be a promising candidate for next generation lithium ion batteries due to their stable performance and easy preparation. However, their inherent low capacity impedes their wide application compared to commercial carbon nanomaterials. Here we present a unique in situ grafting-graphitization method to achieve a ternary nanocomposite of C/SiO x /TiO2 ultrathin nanobelts with a core-shell heterostructure. The obtained ternary nanocomposite integrates the merits of high specific capacity of SiO x , the excellent mechanical stability of graphite-like carbon and the high reactivity of TiO2. Cyclic voltammetric curves and cycling performance manifest the optimal ternary nanocomposite and deliver a very high initial specific capacity of ∼1196 mA h g-1 with both good rate capability (∼200 mA h g-1 up to 10 C) and especially enhanced cycle stability. Our work demonstrates that building hierarchical core-shell heterostructures is an effective strategy to improve capacity and cycling performance in other composite anodes for electrochemical energy storage materials.

Characterization of Nanoparticle Batch-To-Batch Variability.

A central challenge for the safe design of nanomaterials (NMs) is the inherent variability of NM properties, both as produced and as they interact with and evolve in, their surroundings. This has led to uncertainty in the literature regarding whether the biological and toxicological effects reported for NMs are related to specific NM properties themselves, or rather to the presence of impurities or physical effects such as agglomeration of particles. Thus, there is a strong need for systematic evaluation of the synthesis and processing parameters that lead to potential variability of different NM batches and the reproducible production of commonly utilized NMs. The work described here represents over three years of effort across 14 European laboratories to assess the reproducibility of nanoparticle properties produced by the same and modified synthesis routes for four of the OECD priority NMs (silica dioxide, zinc oxide, cerium dioxide and titanium dioxide) as well as amine-modified polystyrene NMs, which are frequently employed as positive controls for nanotoxicity studies. For 46 different batches of the selected NMs, all physicochemical descriptors as prioritized by the OECD have been fully characterized. The study represents the most complete assessment of NMs batch-to-batch variability performed to date and provides numerous important insights into the potential sources of variability of NMs and how these might be reduced.

Natural assembly of a ternary Ag-SnS-TiO2 photocatalyst and its photocatalytic performance under simulated sunlight.

Natural assembly method was utilized to prepare a novel ternary Ag-SnS-TiO2 nanocomposite, in which TiO2 nanobelts were used as templates. The co-loading of Ag and SnS nanoparticles endows TiO2 nanobelts with enhanced photocatalytic capability, resulting from the broadened light absorption spectra and decreased band gaps. Comparing with raw TiO2 nanobelts and commercial Degussa P25, an improvement in photodegradation of simulated organic pollutants was successfully demonstrated due to the decreasing recombination of photogenerated electron-hole pairs. Our work presents a new strategy for the preparation of ternary TiO2-based photocatalysts in the practical application of wastewater treatment.

Modification of hemp shiv properties using water-repellent sol-gel coatings.

For the first time, the hydrophilicity of hemp shiv was modified without the compromise of its hygroscopic properties. This research focused on the use of sol-gel method in preparation of coatings on the natural plant material, hemp shiv, that has growing potential in the construction industry as a thermal insulator. The sol-gel coatings were produced by cohydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) using an acidic catalyst. Methyltriethoxysilane (MTES) was added as the hydrophobic precursor to provide water resistance to the bio-based material. Scanning electron microscopy (SEM) and focused ion beam (FIB) have been used to determine the morphological changes on the surface as well as within the hemp shiv. It was found that the sol-gel coatings caused a reduction in water uptake but did not strongly influence the moisture sorption behaviour of hemp shiv. Fourier transformed infrared (FTIR) spectroscopy shows that the coating layer on hemp shiv acts a shield, thereby lowering peak intensity in the wavelength range 1200-1800 cm-1. The sol-gel coating affected pore size distribution and cumulative pore volume of the shiv resulting in tailored porosity. The overall porosity of shiv decreased with a refinement in diameter of the larger pores. Thermal analysis was performed using TGA and stability of coated and uncoated hemp shiv have been evaluated. Hemp shiv modified with sol-gel coating can potentially develop sustainable heat insulating composites with better hygrothermal properties.

Role of physical and chemical interactions in the antibacterial behavior of ZnO nanoparticles against E. coli.

Zinc oxide (ZnO) nanoparticles (NPs) exhibit antibacterial activity against both Gram-positive and Gram-negative bacteria. However, the antimicrobial mechanism of ZnO NPs remains unclear. In this study, we investigated the interactions among ZnO NPs, released chemicals (Zn(2+) and Reactive Oxygen Species, ROS) and Escherichia coli (E. coli) cells. ZnO NPs without contacting with bacterial cells showed strong antibacterial effect. The results of the leakage of intracellular K(+) and integrity of carboxyfluoresce in-filled liposomes showed that ZnO NPs have antimicrobial activity against E. coli by non-specifically disrupting E. coli membranes. Traces of zinc ions (1.25mg/L) and hydrogen peroxide (from 1.25 to 4.5µM/L) were detected in ZnO NPs suspensions, but was insufficient to cause the antibacterial effect. However, the addition of radical scavengers suppressed the bactericidal effect of ZnO coated films against E. coli, potentially implicating ROS generation, especially hydroxyl radicals, in the antibacterial ability of ZnO NPs.

Differential expression of anthocyanin biosynthetic genes and transcription factor PcMYB10 in pears (Pyrus communis L.).

Anthocyanin biosynthesis in various plants is affected by environmental conditions and controlled by the transcription level of the corresponding genes. In pears (Pyrus communis cv. 'Wujiuxiang'), anthocyanin biosynthesis is significantly induced during low temperature storage compared with that at room temperature. We further examined the transcriptional levels of anthocyanin biosynthetic genes in 'Wujiuxiang' pears during developmental ripening and temperature-induced storage. The expression of genes that encode flavanone 3-hydroxylase, dihydroflavonol 4-reductase, anthocyanidin synthase, UDP-glucose: flavonoid 3-O-glucosyltransferase, and R2R3 MYB transcription factor (PcMYB10) was strongly positively correlated with anthocyanin accumulation in 'Wujiuxiang' pears in response to both developmental and cold-temperature induction. Hierarchical clustering analysis revealed the expression patterns of the set of target genes, of which PcMYB10 and most anthocyanin biosynthetic genes were related to the same cluster. The present work may help explore the molecular mechanism that regulates anthocyanin biosynthesis and its response to abiotic stress at the transcriptional level in plants.