Polydopamine contained hydrogel nanocomposites with combined antimicrobial and antioxidant properties for accelerated wound healing

Overproduction of reactive oxygen species (ROS) in infected wounds induces a tremendous inflammatory reaction to delay wound healing. To address this problem, we designed a multifunctional polyacrylamide/PVA-based hydrogel containing synthesized poly(1-glycidyl-3-butylimidazolium salicylate) (polyGBImSal) and fabricated polydopamine-coated polyphenolic nanosheet (PDA@PNS) for wound dressing. The PDA@PNS particles were designed to induce I) antioxidant and anti-inflammatory features through ROS-scavenging and II) cell adhesive properties by the existing polydopamine into the hydrogels. The poly(ionic liquid)-based polyGBImSal was designed to allocate effective hydrogel antimicrobial activity. The fabricated hydrogel nanocomposites showed excellent properties in the swelling ratio, cell adhesiveness, protein adsorption, and anti-inflammatory, proving their general performance for application in wound healing. Furthermore, these hydrogels showed high antimicrobial activity (over 95 %) against three common wound-infecting pathogenic microbes: Escherichia coli, Staphylococcus aureus, and Candida albicans. The healing process of full-thickness dermal wounds in rats was accelerated by applying hydrogel nanocomposites with 0.5 wt% of PDA@PNS and 28 wt% of polyGBImSal. The wound closure contraction attained full closure, reaching 100 %, after 14 days, contrasted with the control group employing commercial wound dressing (Tegaderm), which achieved a closure rate of 68 % within the equivalent timeframe. These results make these hydrogel nanocomposites promising candidates for multifunctional wound dressing applications.

A novel composite hydrogel for solar evaporation enhancement at air-water interface

This paper reports a facile approach to synthesize a novel composite hydrogel with graphene oxide (GO), silica aerogel (SA), acrylamide (AM), and poly(vinyl alcohol) (PVA) through physical and chemical cross-linking method. The composite hydrogel (GO/SA PAM-PVA hydrogel) exhibits excellent solar evaporation property, good water transmission capacity, and floatability. The GO nanosheets dispersed homogeneously in the hydrogel could provide prominent photothermal conversion efficiency to heat water for evaporation. Excellent hydrophilicity of hydrogel promotes the water molecules transport from the bottom to the top of the hydrogel, which can increase evaporation efficiency. The SA in the hydrogel makes the GO/SA PAM-PVA hydrogel floatable, which is crucial for improving evaporation efficiency because evaporation occurs primarily at several molecular layers on the surface of the water. Furthermore, the self-cleaning ability derived from SA of the GO/SA PAM-PVA hydrogel surface provides a convenient recycling and reusing process for practical applications. The evaporation mass of seawater achieved by the GO/SA PAM-PVA hydrogel is 6 times higher than that of traditional process at an optical density of 2 kW m^-2 for 30 min. Meanwhile, the evaporation efficiency of GO/SA PAM-PVA hydrogel remains good during reuse.

Bioinspired Edible Lubricant-Infused Surface with Liquid Residue Reduction Properties

Inspired by nature's water-repellent plants, the superhydrophobic surface (SHS) and the lubricant-infused surface (LIS) possess potentials in various fields of application. In particular, the edible SHS and the edible LIS (ELIS) are suitable for the role of high-valued liquid food residue reduction. In this study, the ELIS was introduced through a facile spray method and direct lubricant infusion. Four types of ELISs were fabricated: carnauba wax with ethyl oleate infusion, carnauba wax with cooking oil infusion, beeswax with ethyl oleate infusion, and beeswax with cooking oil infusion. The carnauba wax-coated ELIS has better slipperiness, while the beeswax-coated ELIS has better transparency. The ethyl oleate-infused ELIS possesses ELIS to SHS transformable ability, and the cooking oil-infused ELIS also possesses better slipperiness and has the affordable advantage. Moreover, the material selection of ELIS is accessible, renewable, green, recyclable, and edible. The results illustrated that ELIS has advantages of long-term effectiveness and impact resistance over edible SHS and indicated that the ELIS can be facilitated for the manufacture of a multifunctional liquid residue reduction surface with food safety assurance.

Optimized synthesis of novel hydrogel for the adsorption of copper and cobalt ions in wastewater

Metal ions in wastewater endanger the environment and even human life. In this study, an optimized method was used to synthesize an excellent hydrogel to treat these metal ions. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), and applied to treat the Cu(ii) and Co(ii) ions in wastewater. In the adsorption experiment, the influential factors such as pH, adsorption time, adsorbent dosage and concentration of heavy metal ions and regeneration efficiency were evaluated, and the adsorption kinetics, isotherms and thermodynamics were studied. The orthogonal optimization results show that the best condition for synthesis was when the degree of neutralization of acrylic acid (A) was 70%, the quantity of glucose (B) was 0.2 g, the quantity of chitosan (C) was 0.05 g, and the quantity of initiator (D) was 0.03 g. The influence of the four factors was in the order D > B > C > A. The adsorption performance was optimal under neutral conditions and the dosage of 0.02 g adsorbent was chosen as the best. Experiments show that the composite hydrogels exhibited excellent performance under optimal conditions: at 20 °C and pH = 7, the adsorption capacity of 100 mg L⁻¹ of Cu(ii) by 0.01 g hydrogel was 286 mg g⁻¹. The adsorption process of heavy metal ions by hydrogels conforms to pseudo-second-order kinetics and Langmuir isotherm model, which indicate a spontaneous endothermic reaction. Moreover, after five cycles, the removal rates of Cu(ii) and Co(ii) were 81% and 74.8%, respectively.

Metal ions in wastewater endanger the environment and even human life. In this study, an optimized method was used to synthesize an excellent hydrogel to treat these metal ions.

Preparation of Self-supporting Bagasse Cellulose Nanofibrils Hydrogels Induced by Zinc Ions

Cellulose hydrogels are often prepared from native cellulose through a direct cellulose dissolution approach that often involves tedious process and solvent recovery problems. A self-supporting cellulose hydrogel was prepared by gelation of the TEMPO-oxidized bagasse cellulose nanofibrils (CNF) triggered by strong crosslinking between carboxylate groups and Zn²⁺. TEMPO process was used to generate negatively charged carboxylate groups on CNF surface to provide a high binding capability to Zn²⁺. Three TEMPO-oxidized CNFs of different carboxylate contents were prepared and characterized. TEM and AFM microscopes suggested that the sizes of CNFs were fined down and carboxylated cellulose nanofibrils (TOCNFs) of 5–10 nm wide, 200–500 nm long, and carboxylate contents 0.73–1.29 mmol/g were obtained. The final structures and compressive strength of hydrogels were primarily influenced by interfibril Zn²⁺-carboxylate interactions, following the order of TOCNFs concentration > content of carboxylate groups > concentration of zinc ions. A CO₂ sensitive self-supporting cellulose hydrogel was developed as a colorimetric indicator of food spoilage for intelligent food packaging applications.

Bio-inspired Edible Superhydrophobic Interface for Reducing Residual Liquid Food

Significant wastage of residual liquid food, such as milk, yogurt, and honey, in food containers has attracted great attention. In this work, a bio-inspired edible superhydrophobic interface was fabricated using U.S. Food and Drug Administration-approved and edible honeycomb wax, arabic gum, and gelatin by a simple and low-cost method. The bio-inspired edible superhydrophobic interface showed multiscale structures, which were similar to that of a lotus leaf surface. This bio-inspired edible superhydrophobic interface displayed high contact angles for a variety of liquid foods, and the residue of liquid foods could be effectively reduced using the bio-inspired interface. To improve the adhesive force of the superhydrophobic interface, a flexible edible elastic film was fabricated between the interface and substrate material. After repeated folding and flushing for a long time, the interface still maintained excellent superhydrophobic property. The bio-inspired edible superhydrophobic interface showed good biocompatibility, which may have potential applications as a functional packaging interface material.

Hydrogels with high mechanical strength cross-linked by a rosin-based crosslinking agent

A novel type of DN hydrogel, prepared by micellar copolymerization of acrylamide and rosin-based crosslinking agent in a micellar solution of SDS. The hydrogels could form both chemical crosslinks and hydrophobic association crosslinked centers.