Latest ArticlesSurgical suture is commonly used in clinic due to its action in accelerating the process of wound healing. However, difficultly handling in minimally invasive surgery and bacteria-induced infection usually limit its use in a wide range of applications. Here, we report a facile scalable strategy to fabricate surgical sutures with shape memory function and antibacterial activity for wound healing. Specifically, a shape memory polyurethane (SMPU) with a transition temperature (Ttrans) at 41.3 ℃ was synthesized by adjusting the mole ratio of the hard/soft segment, and then the shape memory surgical sutures containing polyhexamethylene biguanide hydrochloride (PHMB) as a model drug for antibacterial activity were fabricated by a facile scalable one-step wet-spinning approach, in which PHMB was directly dissolved in the coagulation bath that enable its loading into the sutures through the dual diffusion during the phase separation. The prepared sutures were characterized by their morphology, mechanical properties, shape memory, antibacterial activity, as well as biocompatibility before the wound healing capability was tested in a mouse skin suture-wound model. It was demonstrated that the optimized suture is capable of both shape memory function and antibacterial activity, and promote wound healing, suggesting that the facile scalable one-step wet-spinning strategy provides a promising tool to fabricate surgical sutures for wound healing.
Recent studies have shown impressive transport behaviors of water and ions within lamellar MXene membranes, which endows great promise in developing advanced separation application based high performance MXene membranes. However, most of the researches focused on modification of MXene nanoflakes and optimizing interlayer distance, leaving the impact of membrane fabrication process marginal. In this work, we studied the water flux of membranes made by vacuum filtration using delaminated MXene nanoflakes as the building-blocks. Our results show that the water permeability is extremely sensitive to the process, especially at the drying process, loading and deposit rate of nanoflakes (the feeding concentration). We find that the voids from less ordered stack rather than in-plane defects and interlayer galleries contribute to the large water permeability. The voids can be effectively avoided via deposition of MXene nanoflakes at a slow rate. Manipulating the stack of MXene nanoflakes during vacuum filtration and drying are critical for development of MXene membranes with desired performance for water permeation.
Due to the diversity and feasibility of structural modification for organic molecules, organic-based redox flow batteries (ORFBs) have been widely investigated, especially in aqueous solution under neutral circumstance. In this work, a symmetric aqueous redox flow battery (SARFB) was rationally designed by employing a bipolar redox active molecule (N, N'-dimethyl-4, 4-bipyridinium diiodide, MVI2) as both cathode and anode materials and combining with an anion exchange membrane. For one MVI2 flow battery, MV2+/MV·+ and I-/I3- serve as the redox couples of anode and cathode, respectively. The MVI2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles, and crossover problem was prohibited. The comparable conductivity of MVI2 water solution enabled to construct a battery even without using supporting electrolyte. Besides, the bipolar character of MVI2 battery with/without supporting electrolyte was investigated in the voltage range between -1.2 V and 1.2 V, showing excellent stable cycling stability during the polarity-reversal test.
The carbon quantum dots (CQDs) and their functionalized materials are promising in biomedical field because of their unique properties; meanwhile, a growing concern has been raised about the potential toxicity of these modified materials in biosystem. In this study, we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs (NCQDs) and folic acid-modified CQDs (FA-CQDs), and compared the toxicity and biocompatibility with each other in vitro and in vivo. L929, C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro. No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL. Among these materials, the FA-CQDs show a much lower toxicity. Moreover, in vivo toxicity studies were performed on the nude mice for 15 days. The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution (PBS) after 15 days. The results of the multifarious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration. Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.
The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them. Understanding the interaction mechanism between the internal driving forces of the crystal and external inducing forces of the surfaces is the prerequisite of controlling and obtaining the desirable morphologies. In this work, the dynamic density functional theory was applied to construct the free energy functional expression of polyethylene (PE) lattice, and the micro-dynamic evolution processes of PE lattice morphology near the surfaces with different properties were observed to reveal the interaction mechanism at atomic scale. The results showed that the physical and chemical properties of the external surfaces synergistically affect the morphologies in both the defect shapes and the distribution of the defect regions. In the absence of the contact surfaces, driven by the oriented interactions among different CH2 groups, PE lattices gradually grow and form a defect-free structure. Conversely, the presence of contact surfaces leads to lattice defects in the interfacial regions, and PE lattice shows different self-healing abilities around different surfaces.
Peony pollen is a cheap and readily available biomass material with a relatively high protein content. In this work, it was employed as an N-rich precursor to prepare the nitrogen-doped porous carbon for supercapacitor application. The porous carbon microspheres were prepared through a hydrothermal method and subsequent carbonization process. Notably, ammonium borofruoride and potassium hydroxide were employed respectively as an etchant and an activator to modify the porosity of the materials. The as prepared ANPPCs-700 has a super high BET specific surface area of 824.69 m2/g. The microstructure, chemical state and electrochemical properties of the product were investigated in detail. The prepared nitrogen-doped carbon microspheres exhibits excellent specific capacity of 209 F/g at a current density of 1 A/g and remained 92.5% of the initial capacitance after 5000 deep cycles at 5 A/g.
The 1, 3-dipolar cycloaddition reaction of dimethyl hex-2-en-4-ynedioate with azomethine ylides derived from reaction of L-proline with various isatins in methanol selectively resulted in the formation of functionalized spiro[indoline-3, 3'-pyrrolizine]acrylates as main products and spiro[indoline-3, 3'-pyrrolizine]propiolates as minor products. This result indicated that the electron-deficient alkyne has higher reactivity than that of electron-deficient alkene in 1, 3-dipolar cycloaddition reaction.
Herein, we first report one-step synthesis of uniform Mo2C microflowers (MCMFs) from low-cost precursors via industrialized solid-state strategy. With fine optimization in precursor ratio and pyrolysis temperatures, the as-fabricated MCMFs are assembled well with interconnected single-crystalline nanosheet subunits. More encouragingly, the resultant MCMFs are further highlighted as a competitive anode with robust and long-duration lithium-storage behaviors towards high-performance Li-ion batteries
Reusable palladium nanoparticles highly dispersed in porous and hydrophilic interpenetrating polymer networks (IPN), i.e., Pd@IPN hybrid gels, are employed for catalysis of Suzuki and Heck coupling reactions. Good yields are obtained with high turnover frequencies when the reactions are run with very low Pdloadings. The use of IPN gives better recyclability than that of crosslinked polyvinyl alcohol alone. The polymer networks allow the reactants to have easy access to the Pd metals. The catalysts combine high activity with the reusability offered by the heterogeneous system, without the need for strong coordination or chelating ligands.
The compound[(CH3)2CH-C3H17N] [CoBr4] (1) based on quinuclidine derivatives was achieved by the solution synthetic method and characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structural analysis and dielectric measurement, respectively. Variable-temperature single-crystal X-ray diffraction suggested that the compound underwent the phase transition from the space group C2/c to Cc. The polarization curve was measured using the Sawyer-Tower circuit. The structural phase transitions of 1 was ascribed to the distortion of a[(CH3)2CH-C3H17N]2+ cation from this inorganic-organic hybrid material[(CH3)2CH-C3H17N] [CoBr4]. The strong change in dielectric anomalies makes compound 1 a suitable candidate for promising switchable dielectric materials. This work represents a feasible strategy thought for the targeted harvesting of low temperature ferroelectrics.
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