Magnetically Driven Cactus Spinelike Superhydrophobic Fe3O4 Vertical Array for High-Performance Fog Harvesting.

Cactus spinelike materials have attracted much attention due to high fog harvesting efficiency, but great challenges in structure fabrication and structural controllability still remain. In this study, we proposed a magnetically driven spray-coating method to fabricate a cactus spinelike superhydrophobic Fe3O4 vertical array on nonwoven cotton fabric. This method is simple and controllable; a mixture containing magnetic Fe3O4 particles and organosilicon resin was atomized into tiny droplets and arranged along the magnetic field lines. Different from the traditional method to prepare a cactus spinelike structure via liquid flow under magnet, which is usually accompanied with a big structure size and an unobvious structure feature due to the high viscosity of magnetic liquid. However, if the magnetic liquid is transformed into tiny magnetic droplets by a spraying method, it is promising to prepare micrometer-scale conical structures, and the reduction degree of bionic structures is high. When the fabricated structure is used for fog harvesting, it shows an extremely high efficiency of approximately 6.33 g cm-2 h-1, which is superior to most state-of-the-art fog harvesting materials. Considering the advantages of simplicity, structure controllability, and high fog harvesting rate, the reported strategy provides an avenue to build up high-performance fog harvesting materials.

Bi- and trinuclear copper(I) complexes of 1,2,3-triazole-tethered NHC ligands: synthesis, structure, and catalytic properties.

A series of copper complexes (3-6) stabilized by 1,2,3-triazole-tethered N-heterocyclic carbene ligands have been prepared via simple reaction of imidazolium salts with copper powder in good yields. The structures of bi- and trinuclear copper complexes were fully characterized by NMR, elemental analysis (EA), and X-ray crystallography. In particular, [Cu2(L2)2](PF6)2 (3) and [Cu2(L3)2](PF6)2 (4) were dinuclear copper complexes. Complexes [Cu3(L4)2](PF6)3 (5) and [Cu3(L5)2](PF6)3 (6) consist of a triangular Cu3 core. These structures vary depending on the imidazolium backbone and N substituents. The copper-NHC complexes tested are highly active for the Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction in an air atmosphere at room temperature in a CH3CN solution. Complex 4 is the most efficient catalyst among these polynuclear complexes in an air atmosphere at room temperature.

Antibacterial hyaluronic acid hydrogels with enhanced self-healing properties via multiple dynamic bond crosslinking.

The self-healing hydrogel offering intrinsic antibacterial activity is often required for the treatment of wounds because it can provide effective wound protection and prevent wound infection. Herein, antibacterial hyaluronic acid hydrogels with enhanced self-healing performances are prepared by multiple dynamic-bond crosslinking between aldehyde hyaluronic acid, 3, 3'- dithiobis (propionyl hydrazide) and fungal-sourced quaternized chitosan. Due to the formation of these different types of reversible interactions e.g. hydrazone bonds, disulfide bonds, and electrostatic interactions, the hyaluronic acid hydrogels can gel rapidly and exhibit excellent self-healing ability, which can heal completely within 1 h. Furthermore, the hydrogels show good antibacterial activity against E. coli and S. aureus with an inhibition ratio of ~100 % and above 75 %, respectively. Additionally, the hydrogels are cytocompatible, which makes them the potential for biomedical applications e.g. cell culture, tissue engineering, and wound dressing.

Magnetically driven Janus conical vertical array for all-weather freshwater collection.

The engineering of multifunctional structures with special surface wettability is highly desirable for all-weather freshwater production, but relevant research is scarce. In this study, a Janus conical vertical array was designed and fabricated via a magnetically driven spray-coating method for the first time. Benefiting from the special structure and wettability enhancement of the array in terms of solar absorption, fog capture and merging, droplet movement and evaporation area, all-weather freshwater production consisting of high-quality daytime solar vapor generation (water evaporation rate approximately 2.43 kg m-2 h-1, 1 kW m-2) and nighttime fog collection (water collection rate approximately 3.536 g cm-2 h-1) can be realized concurrently. When the designed array is employed for outdoor environments (114°35'E, 30°38'N, average daily temperature 34.9 °C, average daily humidity 64.0%), reliable and efficient daily pure water yields of 19.13 kg m-2-26.09 kg m-2 are obtainable. We believe that the proposed strategy for fabricating a Janus conical vertical array is novel in the integration of solar vapor generation and fog collection, which has great significance for all-weather freshwater production.

Macro-porous structured aerogel with enhanced ab/desorption kinetics for sorption-based atmospheric water harvesting.

Sorption-based atmospheric water harvesting (SAWH) has been proven to be a promising method to alleviate the impact of the water crisis on human activities. However, the low water-sorption capacity and sluggish ab/desorption kinetics of current SAWH materials make it difficult to achieve high daily water production. In this study, a photothermal porous sodium alginate-tannic acid-5/Fe3+@lithium chloride aerogel (SA-TA-5/Fe3+@LiCl) with macroporous structure (average pore diameter ∼43.67 µm) and high solar absorbance (∼98.4 %) was fabricated via Fe3+-induced crosslinking and blackening methods. When it is employed for SAWH, moisture can enter the inner space of the aerogel and contact highly hygroscopic lithium chloride (LiCl) more easily via macroporous channels, resulting in the water uptake for the SA-TA-5/Fe3+@LiCl aerogel reaching approximately 1.229 g g-1 under dry conditions (relative humidity (RH) âˆ¼ 45 %, 25 °C) after a short time (4 h) moisture absorption, and releasing as much as 97.7 % of the absorbed water under 1 sun irradiation within 2 h. As a proof of concept, it is estimated that the daily water yield of the fabricated SA-TA/Fe3+@LiCl aerogel can reach approximately 4.65 kg kg-1 in conditions close to the real outdoor environment (RH âˆ¼ 45 %, 25 °C), which satisfies the daily minimum water consumption of two adults. This study demonstrates a novel strategy for developing advanced solar-driven SAWH materials with enhanced ab/desorption kinetics and efficient water sorption-desorption properties.

Flexible dual-functionalized hyaluronic acid hydrogel adhesives formed in situ for rapid hemostasis.

Hydrogel adhesives integrating both rapid and strong adhesion to blooding tissues and biocompatibility are highly desired for fast hemostasis. Herein, a flexible hyaluronic acid hydrogel adhesive is fabricated via photocrosslinking of the solution originating from dopamine-conjugated maleic hyaluronic acid (DMHA) in situ. The introduction of acrylate groups with high substitutions into the hydrogel matrix endows the adhesive with rapid gelation and strong tissue adhesion properties through photopolymerization. Moreover, the high substitution of catechol groups with unoxidized state can not only induce red blood cell aggregation and platelets adhesion but also adhere to wound tissue to further enhance hemostasis. Based on its bio-adhesion and procoagulant activity, the DMHA hydrogel formed in situ reveals superior hemostatic performance in the rat liver injury model and noncompressible hemorrhage model, and rabbit femoral artery puncture model, compared to commercial products (gauze, absorbable gelatin sponge) and oxidized DMHA (SMHA) hydrogel. Besides, the hydrogel exhibited good adaptability, biodegradability, and superior cytocompatibility as well as negligible inflammation. This hydrogel adhesive is a promising biological adhesive for hemorrhage control.

Dual-crosslinked hyaluronic acid hydrogel with self-healing capacity and enhanced mechanical properties.

Self-healing hydrogels can repair their cracks, and restore their original properties. However, self-healing hydrogels usually face low mechanical strength and poor stability. By the dual crosslinking strategy, a self-healing hyaluronic acid-based hydrogel with enhanced strength was fabricated by dynamic acylhydrazone linkages between aldehyde-modified maleic sodium hyaluronate and 3,3'-dithiobis (propionylhydrazide) and subsequent photopolymerization among maleic groups in the hydrogel network. The hydrogels exhibit fast gelation and excellent self-healing capability due to the dynamic and reversible characteristics of acylhydrazone and disulfide linkages. Furthermore, the dual crosslinking increase the mechanical strength of the hydrogels and prolong their stabilization time. Swelling behaviors, morphology, and mechanical properties could be adjusted by altering the molar ratio of -NH-NH2/-CHO. Besides, the hydrogels displayed interesting pH-responsiveness and cytocompatibility. The hydrogels have potential applications in cell culture, drug delivery, and 3D bioprinting.

Strengthened Decellularized Porcine Valves via Polyvinyl Alcohol as a Template Improving Processability.

The heart valve is crucial for the human body, which directly affects the efficiency of blood transport and the normal functioning of all organs. Generally, decellularization is one method of tissue-engineered heart valve (TEHV), which can deteriorate the mechanical properties and eliminate allograft immunogenicity. In this study, removable polyvinyl alcohol (PVA) is used to encapsulate decellularized porcine heart valves (DHVs) as a dynamic template to improve the processability of DHVs, such as suturing. Mechanical tests show that the strength and elastic modulus of DHVs treated with different concentrations of PVA significantly improve. Without the PVA layer, the valve would shift during suture puncture and not achieve the desired suture result. The in vitro results indicate that decellularized valves treated with PVA can sustain the adhesion and growth of human umbilical vein endothelial cells (HUVECs). All results above show that the DHVs treated with water-soluble PVA have good mechanical properties and cytocompatibility to ensure post-treatment. On this basis, the improved processability of DHV treated with PVA enables a new paradigm for the manufacturing of scaffolds, making it easy to apply.

One-step fabrication of all-in-one three-dimensional porous polypyrrole/polydopamine structure for efficient solar vapor generation.

High-quality solar evaporators with all-in-one design are highly desirable for vapor generation, but relevant research is scarce. In this study, a three-dimensional (3D) porous polypyrrole/polydopamine (PPY/PDA) structure was fabricated via a simple heating-assisted rapid oxidative polymerization method. The obtained evaporator has multiple features, and can simultaneously provide rapid water transport channels (average pore sizes âˆ¼ 18.37 nm), low thermal conductivity (0.071 W m-1 K-1), high solar absorbance (97.08%), and good mechanical properties. When it is employed as an evaporator, the calculated water evaporation rate is approximately 2.12 kg m-2h-1, which is comparable to other reported 3D evaporators. Additionally, the evaporator displays great potential for purification toward various nonpotable water, as well as reliable pure water yields in an outdoor application (from 8:00 am to 5:00 pm, the evaporator can produce at least 13.95 L of drinkable water for a 1 m2 sample). We believe that the proposed strategy to fabricate all-in-one evaporators has great significance for scientific research and practical applications.

Biomechanical Scaffolds of Decellularized Heart Valves Modified by Electrospun Polylactic Acid.

Enhancing the mechanical properties and cytocompatibility of decellularized heart valves is the key to promote the application of biological heart valves. In order to further improve the mechanical properties, the electrospinning and non-woven processing methods are combined to prepare the polylactic acid (PLA)/decellularized heart valve nanofiber-reinforced sandwich structure electrospun scaffold. The effect of electrospinning time on the performance of decellularized heart valve is investigated from the aspects of morphology, mechanical properties, softness, and biocompatibility of decellularized heart valve. Results of the mechanical tests show that compared with the pure decellularized heart valve, the mechanical properties of the composite heart valve were significantly improved with the tensile strength increasing by 108% and tensile strain increased by 571% when the electrospinning time exceeded 2 h. In addition, with this electrospinning time, the composite heart valve has a certain promoting effect on the human umbilical vein endothelial cells proliferation behavior. This work provides a promising foundation for tissue heart valve reendothelialization to lay the groundwork for organoid.

Bioinspired Natural Magnolol-Based Adhesive with Strong Adhesion and Antibacterial Properties for Application in Wet and Dry Environments.

The development of environmentally friendly, green, and nontoxic adhesives with excellent dry and wet adhesion properties is of great attraction. In nature, barnacles and mussels exhibit strong adhesion by secreting a hydroxyl-rich dopa. Inspired by their adhesion mechanism, a simple biobased MAG-PETMP (MP) adhesive was prepared from magnolol (MAG) and pentaerythritol tetra (3-mercaptopropionate) (PETMP) by a thiol-ene click chemistry reaction. MP as an adhesive exhibits high bond strength with other substrates due to hydrogen bonds formed by the abundant hydroxyl groups at the interface and shows an inherent thermosetting network structure. Since MP has a thermosetting network, it exhibits excellent thermal stability, solvent resistance, and high mechanical strength, which make the adhesive stable in a humid environment. The cross-linking degree of MP can be easily controlled by adjusting the molar ratio of MAG and PETMP. Among the synthesized samples, the elongation at break of the MP 1 formulation is 174.27%, which makes it promising for use as a flexible adhesive. Moreover, the inherent antibacterial properties of MAG enable MP to exhibit antimicrobial properties and antibacterial adhesion to some extent. This work provides a simple biomimetic strategy that could enable the application of MAG for adhesives.

Polylactic acid scaffold with directional porous structure for large-segment bone repair.

Biodegradable porous scaffolds with different structure, porosity, and strength play a critical role in the repair and regeneration of defects in bone tissue engineering by changing the proliferation condition for cell. In this study, polylactic acid (PLA) scaffold with directional porous structure is designed and fabricated using the method of ice template and phase inversion for speeding up bone repair by promoting the growth and proliferation of bone cells. The morphology, mechanical properties, hydrophilicity, and wicking properties of PLA scaffolds were characterized by scanning electron microscope, universal testing machine, contact angle tester and wicking rate test, respectively. In vitro biocompatibility has been investigated through measuring cell adhesion, proliferation, and viability on PLA scaffold with directional porous structure. Prepared PLA scaffold was implanted into animals to observe the repair mechanism of large-sized bone defects. This study proposes a novel bioporous scaffold design to induce osteocyte growth at the rat calvaria with a directional pore structure, and the scaffold edges were integrated with the calvaria at week 12, effectively promoting the repair and regeneration of defective bone tissue.

A fast curing assisted spray-coating method to fabricate a robust core-shell structured evaporator with stable solar vapor generation performance.

Solar driven interfacial vapor generation is considered to be an effective strategy to alleviate the impact of water crisis on human activities. However, great efforts of researchers have been devoted to improving the solar steam generation efficiency, while less attention has been paid to the long-term stability of evaporators. Herein, we proposed a robust core-shell structured evaporator prepared by a simple fast curing assisted spray-coating method. Owing to the inherent superelasticity of melamine-formaldehyde (MF) sponge, the finely designed novel 3D core-shell structure, and the quick curing of branched polyethyleneimine (BPEI) and 5-pentaerythritol pentaacrylate (5Acl) induced special knot shaped photothermal coating, the as-obtained evaporator (CB/MF) performed well in vapor generation with a high water evaporation rate of 2.082 kg m-2 h-1 under 1 sun illumination, and the evaporation efficiency reached 123.5%, which is comparable to the state-of-the-art artificial solar evaporator. Even in strict application situations, such as long-term recycling testing for 40 h, 500 compression-release cycles (20%, 40% or 60%), sonication for 12 h, or shaking for 30 h, the water evaporation rate of the obtained evaporator remains at a high level of above 2.00 kg m-2 h-1. Additionally, the evaporator shows effective purification toward high-concentration brine, acid-base solutions, simulated seawater, dye wastewater, and heavy metal wastewater, as well as reliable pure water, providing an outdoor application. With the advantages of a high evaporation rate, stable long-term vapor generation, and effective purification toward various non-potable water sources, we believe that the fabricated core-shell structured CB/MF evaporator is a promising candidate for practical solar steam generation.

TBAF-mediated reactions of 1,1-dibromo-1-alkenes with thiols and amines and regioselective synthesis of 1,2-heterodisubstituted alkenes.

An efficient synthesis of trisubstituted alkenes including 1,2-heterodisubstituted alkenes has been described. Reactions of thiols and amines with 1,1-dibromo-1-alkenes in the presence of TBAF·3H(2)O afford (Z)-2-bromovinyl sulfides and (Z)-2-bromovinyl amines regio- and stereoselectively. The reaction proceeds under catalyst-free conditions with high efficiency. The coupling reactions of the obtained products bearing bromine atoms with phenylacetylene and phenylboronic acid gave trisubstituted alkenes in good to excellent yields. Cross-coupling with various N, O, S, and P nucleophiles selectively generated 1,2-N,O, 1,2-N,S, 1,2-S,P, 1,2-S,S, and 1,2-S,O heterodisubstituted alkenes.

Effect of poly (lactic acid) porous membrane prepared via phase inversion induced by water droplets on 3T3 cell behavior.

Phase inversion induced by water droplets has garnered attention in the field of polymer science as a novel method for preparing porous membranes. This study investigates the effect of the porous structure of poly (lactic acid) (PLA) membranes prepared through phase inversion induced by water droplets at four different temperatures (25, 50, 75, and 100 °C) on the morphology and proliferation of 3T3 cells. The surface properties of the PLA porous membrane, including pore size, pore size distribution, surface roughness, surface hydrophilicity, and cytocompatibility with 3T3 cells, were evaluated. The results indicated that the synthesized PLA membrane had two surfaces with different structures. The upper surface in contact with the water droplets during preparation contained uniformly distributed micropores, whereas the bottom surface was smooth and composed of small particles in contacted with the mold. The upper surface showed high cytocompatibility with 3T3 cells, and the 3T3 cells migrated and grew within the pores at 25 °C. In contrast, the bottom surface exhibited low biocompatibility with the 3T3 cells. Our study has wide-ranging implications and will improve the fabrication and implementation of 3D cultured scaffolds with excellent cytocompatibility.

Dopamine-Modified Hyaluronic Acid Hydrogel Adhesives with Fast-Forming and High Tissue Adhesion.

Commercial or clinical tissue adhesives are currently limited due to their weak bonding strength on wet biological tissue surface, low biological compatibility, and slow adhesion formation. Although catechol-modified hyaluronic acid (HA) adhesives are developed, they suffer from limitations: insufficient adhesiveness and overfast degradation, attributed to low substitution of catechol groups. In this study, we demonstrate a simple and efficient strategy to prepare mussel-inspired HA hydrogel adhesives with improved degree of substitution of catechol groups. Because of the significantly increased grafting ratio of catechol groups, dopamine-conjugated dialdehyde-HA (DAHA) hydrogels exhibit excellent tissue adhesion performance (i.e., adhesive strength of 90.0 ± 6.7 kPa), which are significantly higher than those found in dopamine-conjugated HA hydrogels (∼10 kPa), photo-cross-linkable HA hydrogels (∼13 kPa), or commercially available fibrin glues (2-40 kPa). At the same time, their maximum adhesion energy is 384.6 ± 26.0 J m-2, which also is 40-400-fold, 2-40-fold, and ∼8-fold higher than those of the mussel-based adhesive, cyanoacrylate, and fibrin glues, respectively. Moreover, the hydrogels can gel rapidly within 60 s and have a tunable degradation suitable for tissue regeneration. Together with their cytocompatibility and good cell adhesion, they are promising materials as new biological adhesives.

Effect of temperature on the thermal property and crystallization behavior of poly (lactic acid) porous membrane prepared via phase separation induced by water microdroplets.

Poly (lactic acid) (PLA)-based porous membrane were fabricated through phase separation induced by water microdroplets at different ambient temperature to unravel the relationship between the physical properties (including thermal properties and crystallization) and preparation temperature. Cross-sectional scanning electron micrographs revealed that the thickness of the membrane decreases with increasing temperature between 25 °C and 100 °C. In the bilayer structure, each layer has a different morphology. Differential scanning calorimetry (DSC) and X-ray diffraction studies indicate that the preparation temperature influences the ratio between imperfect and perfect crystals in the membrane, leading to a bimodal melting peak in the DSC thermogram. The change in the initial decomposition temperature in the thermogravimetric analysis curve is weak, suggesting a negligible effect of the preparation temperature on the thermal stability of the membranes. Thus, PLA porous membranes can be prepared with better crystallinity by controlling the ambient temperature during the phase separation induced by water microdroplets.

Self-healing hyaluronic acid hydrogels based on dynamic Schiff base linkages as biomaterials.

Natural hydrogels are widely investigated for biomedical applications because of their structures similar to extracellular matrix of native tissues, possessing excellent biocompatibility and biodegradability. However, they are often susceptible to mechanical disruption. In this study, self-healing hyaluronic acid (HA) hydrogels are fabricated through a facile dynamic covalent Schiff base reaction. Dialdehyde-modified HA (AHA) precursor was synthesized, and then the AHA/cystamine dihydrochloride (AHA/Cys) hydrogels were formed by blending AHA and Cys at acidic pH levels. By varying Cys to AHA ratio, the hydrogel morphology, swelling and kinetics of gelation could be controlled. Gelation occurred fast, which was predominantly attributed to Schiff base reaction between the dialdehyde groups on AHA and amimo groups on Cys. The hydrogel exhibited improved mechanical properties with increase in Cys content. Furthermore, due to dynamic imine bonds, this hydrogel demonstrated excellent self-healing ability based on the stress after mechanical disruption. Also, it was found to be pH-responsive and injectable. Taken together, this kind of hyaluronic acid hydrogel can provide promising future for various biomedical applications in drug delivery, bioprinting, smart robots and tissue regeneration.

Ortho-functionalization of 2-phenoxypyrimidines via palladium-catalyzed C-H bond activation.

The palladium-catalyzed direct acetoxylation and arylation of 2-aryloxypyrimidine has been described. The aromatic C-H bonds may be functionalized in moderate to excellent yields providing a facile method for the synthesis of phenol derivatives, which show antimycobacterial and herbicidal activities.

Effect of temperature on the morphology of poly (lactic acid) porous membrane prepared via phase inversion induced by water droplets.

Temperature is a critical parameter that can control the morphology of poly (lactic acid) (PLA) porous membranes prepared through phase inversion induced by water droplets. It determines the volatilization rate of the solvent and the exchange rate between the solvent and nonsolvent. In this work, in order to investigate the effect of temperature on the morphology, PLA porous membranes were prepared via phase inversion induced by water droplets at different temperatures. The morphologies of the prepared membranes were observed using scanning electron microscopy, and the volatilization rate of the solvent and the exchange rate between the solvent and nonsolvent were tested separately. The experimental data indicated that the volatilization rate of the solvent was faster than the exchange rate between the solvent and nonsolvent. A uniform porous structure was obtained for the PLA membrane, and the pore size decreased with the increase in temperature from 25 °C to 75 °C. This result indicated that a PLA porous membrane with desired pore size could be achieved by adjusting the ambient temperature.