Sonochemical Synthesis of Natural Polyphenolic Nanoparticles for Modulating Oxidative Stress.

Natural polyphenolic compounds play a vital role in nature and are widely utilized as building blocks in the fabrication of emerging functional nanomaterials. Although diverse fabrication methodologies are developed in recent years, the challenges of purification, uncontrollable reaction processes and additional additives persist. Herein, a modular and facile methodology is reported toward the fabrication of natural polyphenolic nanoparticles. By utilizing low frequency ultrasound (40 kHz), the assembly of various natural polyphenolic building blocks is successfully induced, allowing for precise control over the particle formation process. The resulting natural polyphenolic nanoparticles possessed excellent in vitro antioxidative abilities and in vivo therapeutic effects in typical oxidative stress models including wound healing and acute kidney injury. This study opens new avenues for the fabrication of functional materials from naturally occurring building blocks, offering promising prospects for future advancements in this field.

Eumelanin-like Poly(levodopa) Nanoscavengers for Inflammation Disease Therapy.

In the current years, polydopamine nanoparticles (PDA NPs) have been extensively investigated as an eumelanin mimic. However, unlike natural eumelanin, PDA NPs contain no 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units and may be limited in certain intrinsic properties; superior eumelanin-like nanomaterials are still actively being sought. Levodopa (l-DOPA) is a natural eumelanin precursor and expected to convert into DHICA and further remain within the final product through covalent or physical interactions. Herein, poly(levodopa) nanoparticles [P(l-DOPA) NPs] were synthesized with the assistance of zinc oxide as a supplement to synthetic eumelanin. This study found that P(l-DOPA) NPs had ∼90% DHICA-derived subunits on their surface and exhibited superior antioxidant activity compared to PDA NPs due to their looser polymeric microstructure. Benefitting from a stronger ROS scavenging ability, P(l-DOPA) NPs outperformed PDA NPs in treating cellular oxidative stress and acute inflammation. This research opens up new possibilities for the development and application of novel melanin-like materials.

Size Regulation of Polydopamine Nanoparticles by Boronic Acid and Lewis Base.

Size regulation of polydopamine nanoparticles (PDA NPs) is vital to melanin-inspired materials. The general strategy usually focuses on tuning of the reaction parameters which could affect the dopamine (DA) monomer polymerization process, such as pH, temperature, monomer concentration, etc. The reaction between boronic acids and catechols to form boronic esters has been widely applied in many fields, but little attention has been paid in the size regulation of PDA NPs. Here, it is speculated that the fine size regulation of PDA NPs can be directly achieved by using boronic acids and Lewis base molecules. It is found that these issues could indeed significantly affect the stability of the boronic esters formed by boronic acids and DA, which may further inhibit the monomer polymerization kinetics and tune the particle size of the resulting PDA NPs. It is also found that the several intrinsic properties of PDA NPs such as the free radical scavenging ability, UV spectral absorption, photothermal behavior, and structural color all change with the particle size. It is believed that this work can provide new opportunities for fabricating melanin-inspired PDA NPs with well controlled size and properties.

Effect of Carbonization Temperature on Microstructures and Properties of Electrospun Tantalum Carbide/Carbon Fibers.

Compared with traditional metal materials, carbon-based materials have the advantages of low density, high conductivity, good chemical stability, etc., and can be used as reliable alternative materials in various fields. Among them, the carbon fiber conductive network constructed by electrospinning technology has the advantages of high porosity, high specific surface area and rich heterogeneous interface. In order to further improve the conductivity and mechanical properties of pure carbon fiber films, tantalum carbide (TaC) nanoparticles were selected as conductive fillers. The crystallization degree, electrical and mechanical properties of electrospun TaC/C nanofibers at different temperatures were investigated. As the carbonization temperature increases, the crystallization degree and electrical conductivity of the sample also increases, while the growth trend of electrical conductivity is markedly slowed. The best mechanical properties of 12.39 MPa was achieved when the carbonization temperature was 1200 °C. Finally, through comprehensive analysis and comparison, it can be concluded that a carbonization temperature of 1200 °C is the optimum.

Research Progress of the Ion Activity Coefficient of Polyelectrolytes: A Review.

Polyelectrolyte has wide applications in biomedicine, agriculture and soft robotics. However, it is among one of the least understood physical systems because of the complex interplay of electrostatics and polymer nature. In this review, a comprehensive description is presented on experimental and theoretical studies of the activity coefficient, one of the most important thermodynamic properties of polyelectrolyte. Experimental methods to measure the activity coefficient were introduced, including direct potentiometric measurement and indirect methods such as isopiestic measurement and solubility measurement. Next, progress on the various theoretical approaches was presented, ranging from analytical, empirical and simulation methods. Finally, challenges for future development are proposed on this field.

Wood-Derived High-Mass-Loading MnO2 Composite Carbon Electrode Enabling High Energy Density and High-Rate Supercapacitor.

The simple design of a high-energy-density device with high-mass-loading electrode has attracted much attention but is challenging. Manganese oxide (MnO2 ) with its low cost and excellent electrochemical performance shows high potential for practical application in this regard. Hence, the high-mass-loading of the MnO2 electrode with wood-derived carbon (WC) as the current collector is reported through a convenient hydrothermal reaction for high-energy-density devices. Benefiting from the high-mass-loading of the MnO2 electrode (WC@MnO2 -20, ≈14.1 mg cm-2 ) and abundant active sites on the surface of the WC hierarchically porous structure, the WC@MnO2 -20 electrode shows remarkable high-rate performance of areal/specific capacitance ≈1.56 F cm-2 /45 F g-1 , compared to the WC electrode even at the high density of 20 mA cm-2 . Furthermore, the obtained symmetric supercapacitor exhibits high areal/specific capacitances of 3.62 F cm-2 and 87 F g-1 at 1.0 mA cm-2 and high energy densities of 0.502 mWh cm-2 /12.2 Wh kg-1 with capacitance retention of 75.2% after 10 000 long-term cycles at 20 mA cm-2 . This result sheds light on a feasible design strategy for high-energy-density supercapacitors with the appropriate mass loading of active materials and low-tortuosity structural design while also encouraging further investigation into electrochemical storage.

Wood-Derived, Conductivity and Hierarchical Pore Integrated Thick Electrode Enabling High Areal/Volumetric Energy Density for Hybrid Capacitors.

For the proliferation of the supercapacitor technology, it is essential to attain superior areal and volumetric performance. Nevertheless, maintaining stable areal/volumetric capacitance and rate capability, especially for thick electrodes, remains a fundamental challenge. Here, for the first time, a rationally designed porous monolithic electrode is reported with high thickness of 800 µm (46.74 mg cm-2 , with high areal mass loading of NiCo2 S4 6.9 mg cm-2 ) in which redox-active Ag nanoparticles and NiCo2 S4 nanosheets are sequentially decorated on highly conductive wood-derived carbon (WC) substrates. The hierarchically assembled WC@Ag@NiCo2 S4 electrode exhibits outstanding areal capacitance of 6.09 F cm-2 and long-term stability of 84.5% up to 10 000 cycles, as well as exceptional rate capability at 50 mA cm-2 . The asymmetric cell with an anode of WC@Ag and a cathode of WC@Ag@NiCo2 S4 delivers areal/volumetric energy density of 0.59 mWh cm-2 /3.93 mWh cm-3 , which is much-improved performance compared to those of most reported thick electrodes at the same scale. Theoretical calculations verify that the enhanced performance could be attributed to the decreased adsorption energy of OH- and the down-shifted d-band of Ag atoms, which can accelerate the electron transport and ion transfer.

Exploration of Macroporous Polymeric Sponges As Drug Carriers.

Achieving high drug loading capacity and controlling drug delivery are two main challenges related to drug carriers. In this study, polymeric macroporous sponges with very high pore volume and large porosity are introduced as a new-type of drug carrier. Due to the high pore volume (285 and 166 cm3/g for the sponges with densities of 3.5 and 6.0 mg/cm3, respectively), the sponges exhibit very high drug loading capacities with average values of 1870 ± 114 and 2697 ± 73 mg/g in the present study, which is much higher than the meso and microporous drug carriers (<1500 mg/g). In order to control the release profiles, an additional poly(p-xylylene) (PPX) coating was deposited by chemical vapor deposition on the drug loaded sponge. Consequently, Artemisone (ART) release in the aqueous medium could be retarded, depending on the density of the sponge and the thickness of the coating. In future, the new 3D polymeric sponges would be highly beneficial as drug carriers for the programmed release of drugs for treatment of chronic diseases.

Highly Efficient Reusable Sponge-Type Catalyst Carriers Based on Short Electrospun Fibers.

This study reports on gold nanoparticles (AuNPs) immobilized in a sponge made of short electrospun fibers (Au-sponge), which show surprisingly high reaction rates at extremely low gold amount. Au-sponges are made by freeze-drying of dispersions of short electrospun fibers with preimmobilization of AuNPs. The resulting Au-sponges show very low densities around 7 mg cm-3 corresponding to a pore volume of about 150 mL g-1 , but low surface area and very low amount of AuNPs in the range of 0.29-3.56 wt%. In general, catalysts with immobilized AuNPs show much low reaction rates compared to systems with dispersed AuNPs. By contrast, the Au-sponge catalyst with immobilized AuNPs is discerned here as an extremely efficient catalyst even superior to other systems with dispersed AuNPs. The fidelity of the Au-sponges after reactions is good enough for manifold use and thereby provides a sustainable catalyst design as well.

Spongy Gels by a Top-Down Approach from Polymer Fibrous Sponges.

Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel-like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom-up process. In contrast, the spongy gels are formed by a top-down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel-like material. The spongy gels are independent of a time-consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non-wetting liquids dispersed in the sponge.

Preparation of nanocellulose and its applications in wound dressing: A review.

Nanocellulose, as a nanoscale polymer material, has garnered significant attention worldwide due to its numerous advantages including excellent biocompatibility, thermal stability, non-toxicity, large specific surface area, and good hydrophilicity. Various methods can be employed for the preparation of nanocellulose. Traditional approaches such as mechanical, chemical, and biological methods possess their own distinct characteristics and limitations. However, with the growing deterioration of our living environment, several green and environmentally friendly preparation techniques have emerged. These novel approaches adopt eco-friendly technologies or employ green reagents to achieve environmental sustainability. Simultaneously, there is a current research focus on optimizing traditional nanocellulose preparation methods while addressing their inherent drawbacks. The combination of mechanical and chemical methods compensates for the limitations associated with using either method alone. Nanocellulose is widely used in wound dressings owing to its exceptional properties, which can accelerate the wound healing process and reduce patient discomfort. In this paper, the principle, advantages and disadvantages of each preparation method of nanocellulose and the research findings in recent years are introduced Moreover, this review provides an overview of the utilization of nanocellulose in wound dressing applications. Finally, the prospective trends in its development alongside corresponding preparation techniques are discussed.

Mechanically Controlled Enzymatic Polymerization and Remodeling.

In nature, proteins possess the remarkable ability to sense and respond to mechanical forces, thereby triggering various biological events, such as bone remodeling and muscle regeneration. However, in synthetic systems, harnessing the mechanical force to induce material growth still remains a challenge. In this study, we aimed to utilize low-frequency ultrasound (US) to activate horseradish peroxidase (HRP) and catalyze free radical polymerization. Our findings demonstrate the efficacy of this mechano-enzymatic chemistry in rapidly remodeling the properties of materials through cross-linking polymerization and surface coating. The resulting samples exhibited a significant enhancement in tensile strength, elongation, and Young's modulus. Moreover, the hydrophobicity of the surface could be completely switched within just 30 min of US treatment. This work presents a novel approach for incorporating mechanical sensing and rapid remodeling capabilities into materials.

Cellulose-Based Intelligent Responsive Materials: A Review.

Due to the rapid development of intelligent technology and the pursuit of green environmental protection, responsive materials with single response and actuation can no longer meet the requirements of modern technology for intelligence, diversification, and environmental friendliness. Therefore, intelligent responsive materials have received much attention. In recent years, with the development of new materials and technologies, cellulose materials have become increasingly used as responsive materials due to their advantages of sustainability and renewability. This review summarizes the relevant research on cellulose-based intelligent responsive materials in recent years. According to the stimuli responses, they are divided into temperature-, light-, electrical-, magnetic-, and humidity-responsive types. The response mechanism, application status, and development trend of cellulose-based intelligent responsive materials are summarized. Finally, the future perspectives on the preparation and applications of cellulose-based intelligent responsive materials are presented for future research directions.

A bioinspired antibacterial and photothermal membrane for stable and durable clean water remediation.

Solar-driven steam generation has been considered as a prevalent and sustainable approach to obtain clean fresh water. However, the presence of microorganisms in seawater may cause the biofouling and degradation of polymeric photothermal materials and clog the channels for water transportation, leading to a decrease in solar evaporation efficiency during long-term usage. Herein, we have reported a facile strategy to construct a robust cellulose membrane device coated by tobramycin-doped polydopamine nanoparticles (PDA/TOB@CA). The PDA/TOB@CA membrane not only exhibited synergistic antibacterial behaviors with long-term and sustained antibiotic release profiles, but also achieved a high water evaporation rate of 1.61 kg m-2 h-1 as well as an evaporation efficiency of >90%. More importantly, the high antibacterial activity endowed the PDA/TOB@CA membrane with superb durability for stable reuse over 20 cycles, even in microbe-rich environments. Therefore, we envision that this study could pave a new pathway towards the design and fabrication of robust antibacterial and photothermal materials for long-term and stable clean water production.

A melanin-inspired robust aerogel for multifunctional water remediation.

Solar-driven vapor generation has emerged as a promising wastewater remediation technology for clean water production. However, the complicated and diversified contaminants in wastewater still restrict its practical applications. Herein, inspired by the melanin in nature, a robust aerogel was facilely fabricated for multifunctional water remediation via a one-pot condensation copolymerization of 5,6-dihydroxyindole and formaldehyde. Benefiting from the superhydrophilicity, underwater superoleophobicity, and synergistic coordination effects, the resulting aerogel not only showed excellent performances in underwater oil resistance and oil-water separation ability, but also removed organic dyes and heavy metal ions contaminants in wastewater simultaneously. Moreover, owing to its admirable light harvesting capacity and porous microstructure for fast water transportation, the aerogel-based evaporator exhibited an excellent evaporation rate of 1.42 kg m-2 h-1 with a 91% evaporation efficiency under 1 sun illumination, which can be reused for long-term water evaporation. Note that such a stable evaporation rate could be maintained even in wastewater containing complex multicomponent contaminants. Outdoor evaporation experiments for lotus pond wastewater under natural sunlight also proved its great potential in practical applications. All those promising features of this all-in-one melanin-inspired aerogel may provide new strategies for the development of robust photothermal devices for multifunctional solar-driven water remediation.

A robust and 3D-printed solar evaporator based on naturally occurring molecules.

The interfacial solar desalination has been considered a promising method to address the worldwide water crisis without sophisticated infrastructures and additional energy consumption. Although various advanced solar evaporators have been developed, their practical applications are still restricted by the unsustainable materials and the difficulty of precise customization for structure to escort high solar-thermal efficiency. To address these issues, we employed two kinds of naturally occurring molecules, tannic acid and iron (III), to construct a low-cost, highly efficient and durable interfacial solar evaporator by three-dimensional (3D) printing. Based on a rational structural design, a robust and 3D-printed evaporator with conical array surface structure was developed, which could promote the light harvesting capacity significantly via the multiple reflections and anti-reflection effects on the surface. By optimizing the height of the conical arrays, the 3D-printed evaporator with tall-cone structure could achieve a high evaporation rate of 1.96 kg m-2 h-1 under one sun illumination, with a photothermal conversion efficiency of 94.4%. Moreover, this evaporator was also proved to possess excellent desalination performance, recycle stability, anti-salt property, underwater oil resistance, as well as adsorption capacity of organic dye contaminants for multipurpose water purification applications. It was believed that this study could provide a new strategy to fabricate low-cost, structural regulated solar evaporators for alleviating the dilemma of global water scarcity using abundant naturally occurring building blocks.

One-step fabrication of eco-friendly superhydrophobic fabrics for high-efficiency oil/water separation and oil spill cleanup.

The oily wastewater and oil spill caused by oil leakage accidents are extremely harmful to human health and the environment. Thus, it is very important to exploit superhydrophobic separation materials and technologies for oil/water separation and oil spill cleanup. In this study, using the 1,4-conjugate addition reaction between polyethyleneimine (PEI) and 3-(trimethoxysilyl)propyl acrylate (TMSPA), hydrolysis condensation reaction of TMSPA and dodecyltrimethoxysilane (DTMS) jointly connecting to the surface of hydrophilic silica nanoparticles, and hydrogen bond interaction of the residual amino group on the surface of PEI, covalently-crosslinked rough network structures were constructed on fabric surfaces, which endow PEI/TMSPA/SiO2/DTMS fabrics with excellent superhydrophobic properties. The obtained superhydrophobic fabric not only showed excellent heat resistance and excellent stability to acid, alkali, salt and organic solvents, but also showed good mechanical stability to tape stripping and washing tests. The superhydrophobic, superoleophilic properties and porous structure of the modified fabric make it have excellent oil/water separation efficiency (98.49% after 18 cycles) and oil spill cleanup efficiency (95.35% after 9 cycles). This superhydrophobic PEI/TMSPA/SiO2/DTMS fabric has characteristics of simple preparation, environmental friendliness and scale-up, which makes it a very promising separation material for actual oil/water separation and oil spill cleanup.

Nanocellulose-Based Adsorbents for Heavy Metal Ion.

Heavy metal ions in industrial sewage constitute a serious threat to human health. Nanocellulose-based adsorbents are emerging as an environmentally friendly material platform for heavy metal ion removal based on their unique properties, which include high specific surface area, excellent mechanical properties, and biocompatibility. In this review, we cover the most recent works on nanocellulose-based adsorbents for heavy metal ion removal and present an in-depth discussion of the modification technologies for nanocellulose in the process of assembling high-performance heavy ion adsorbents. By introducing functional groups, such as amino, carboxyl, aldehyde, and thiol, the assembled nanocellulose-based adsorbents both remove single heavy metal ions and can selectively adsorb multiple heavy ions in water. Finally, the remaining challenges of nanocellulose-based adsorbents are pointed out. We anticipate that this review will provide indispensable guidance on the application of nanocellulose-based adsorbents for the removal of heavy metal ions.

Source of Nanocellulose and Its Application in Nanocomposite Packaging Material: A Review.

Food packaging nowadays is not only essential to preserve food from being contaminated and damaged, but also to comply with science develop and technology advances. New functional packaging materials with degradable features will become a hot spot in the future. By far, plastic is the most common packaging material, but plastic waste has caused immeasurable damage to the environment. Cellulose known as a kind of material with large output, wide range sources, and biodegradable features has gotten more and more attention. Cellulose-based materials possess better degradability compared with traditional packaging materials. With such advantages above, cellulose was gradually introduced into packaging field. It is vital to make packaging materials achieve protection, storage, transportation, market, and other functions in the circulation process. In addition, it satisfied the practical value such as convenient sale and environmental protection, reduced cost and maximized sales profit. This review introduces the cellulose resource and its application in composite packaging materials, antibacterial active packaging materials, and intelligent packaging materials. Subsequently, sustainable packaging and its improvement for packaging applications were introduced. Finally, the future challenges and possible solution were provided for future development of cellulose-based composite packaging materials.