Yijing Huang

Polydopamine (PDA) nanoparticles have emerged as an attractive biomimetic photothermal agent in photothermal antibacterial therapy due to their ease of synthesis, good biodegradability, long-term safety, and excellent photostability. However, the therapeutic effects of PDA nanoparticles are generally limited by the low photothermal conversion efficiency (PCE). Herein, PDA@Ag nanoparticles are synthesized via growing Ag on the surface of PDA nanoparticles and then encapsulated into a cationic guar gum (CG) hydrogel network. The optimized CG/PDA@Ag platform exhibits a high PCE (38.2%), which is more than two times higher than that of pure PDA (16.6%). More importantly, the formulated CG/PDA@Ag hydrogel with many active groups can capture and kill bacteria through effective interactions between hydrogel and bacteria, thereby benefiting the antibacterial effect. As anticipated, the designed CG/PDA@Ag system combined the advantages of PDA@Ag nanoparticles (high PCE) and hydrogel (preventing aggregation of PDA@Ag nanoparticles and possessing inherent antibacterial ability) is demonstrated to have superior antibacterial efficacy both in vitro and in vivo. This study develops a facile approach to boost the PCE of PDA for photothermal antibacterial therapy, providing a significant step forward in advancing the application of PDA nano-photothermal agents.

Polysaccharide hydrogels are widely used in tissue engineering because of their superior biocompatibility and low immunogenicity. However, many of these hydrogels are unrealistic for practical applications as the cost of raw materials is high, and the fabrication steps are tedious. This study focuses on the facile fabrication and optimization of agarose-polydopamine hydrogel (APG) scaffolds for skin wound healing. The first study objective was to evaluate the effects of polydopamine (PDA) on the mechanical properties, water holding capacity and cell adhesiveness of APG. We observed that APG showed decreased rigidity and increased water content with the addition of PDA. Most importantly, decreased rigidity translated into significant increase in cell adhesiveness. Next, the slow biodegradability and high biocompatibility of APG with the highest PDA content (APG3) was confirmed. In addition, APG3 promoted full-thickness skin defect healing by accelerating collagen deposition and promoting angiogenesis. Altogether, we have developed a straightforward and efficient strategy to construct functional APG scaffold for skin tissue engineering, which has translation potentials in clinical practice.

Most commonly used wound dressings have severe problems, such as an inability to adapt to wound shape or a lack of antibacterial capacity, affecting their ability to meet the requirements of clinical applications. Here, a nanocomposite hydrogel (XKP) is developed by introducing polydopamine nanoparticles (PDA NPs) into a food gum matrix (XK, consisting of xanthan gum and konjac glucomannan, both FDA-approved food thickening agents) for skin wound healing. In this system, the embedded PDA NPs not only interact with the food gum matrix to form a hydrogel with excellent mechanical strength, but also act as photothermal transduction agents to convert near-infrared laser radiation to heat, thereby triggering bacterial death. Moreover, the XKP hydrogel has high elasticity and tunable water content, enabling it to adapt to the shape of the wound and insulate it, providing a moist environment suitable for healing. In-vivo skin wound healing results clearly demonstrate that XKP can significantly accelerate the healing of wounds by reducing the inflammatory response and promoting vascular reconstruction. In summary, this strategy provides a simple and practical method to overcome the drawbacks of traditional wound dressings, and provides further options when choosing suitable wound healing materials for clinical applications.

Hydrogen is one of the cleanest energies with potential to have zero carbon emission. Hydrogen storage is a challenging phase for the hydrogen energy application. The safety, cost, and transportation of compressed and liquified hydrogen hinder the widespread application of hydrogen energy. Chemical absorption of hydrogen in solid hydrogen storage materials is a promising hydrogen storage method due to its high storage and transportation performance. Hydrogen storage density, dehydrogenation temperature, and dehydrogenation dynamics are the main challenges for the hydrogen storage materials. The ultimate goal of the system gravimetric capacity was set by the Department of Energy to be 6.5 wt % with a working temperature from −40 to 60 °C. The theoretical densities of most present hydrogen storage materials are even lower than 6.5 wt %, which make it impossible to reach the system gravimetric capacity goal. Only hydrogen storage materials with high theoretical density (≥10 wt %) with further modification have the possibility to reach the goal. However, most of the reviews focus on the research progress of general hydrogen storage materials investigated, many of which have low density. Hydrogen storage materials with high theoretical density including metal borohydrides, metal alanates, ammonia borane, metal amides, and amine metal borohydrides have been reviewed in this article. The pyrolysis and hydrogen absorption conditions of the hydrogen storage materials have been summarized, especially the improvements of the hydrogen storage materials. Furthermore, the challenges of the hydrogen storage materials have been pointed out. Potential hydrogen storage materials and possible modification methods have also been presented and discussed.