Wound-Healing Material with Antibacterial and Antioxidant Functions, Constructed Using Keratin, Hyperbranched Polymers, and MnO2.

Wound healing, a global medical issue, poses a substantial financial burden. Therefore, developing low-cost and highly efficacious wound-healing materials is essential. In this study, we prepared keratin-hyperbranched polymer hydrogel-M (KHBP-M), a multifunctional composite gel, by mixing reduced keratin containing free sulfhydryl groups extracted from human hair waste, hyperbranched polymer (HBP) with double bonds at the end, and MnO2 nanoparticles prepared using the biological template method. Keratin has intrinsic wound-healing properties, and MnO2 is a wound-healing material with both photothermal antibacterial and reactive oxygen species (ROS)-scavenging abilities. KHBP-M showed antibacterial effects against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. When exposed to irradiation (808 nm), the killing ratio for S. aureus reached 99.99%, which is especially suitable for wound environments. A similar trend was noted for E. coli. The composite hydrogel also showed excellent ROS-scavenging ability and could resist oxidative stress in L929 cells. Furthermore, in an animal model of infected wounds, the KHBP-M hydrogel treated with near-infrared light had the fastest wound-healing rate, reaching 82.98% on day 15. Our study provides a promising wound-healing material, with simple preparation methods, easy access to sources, and low cost involved.

Keratin-based wound dressings: From waste to wealth.

Keratin is a natural protein with a high content of cysteine residues (7-13%) and is widely found in hair, wool, horns, hooves, and nails. Keratin possesses abundant cell-binding motifs such as leucine-aspartate-valine (LDV), glutamate-aspartate-serine (EDS), and arginine-glycine-aspartate (RGD), which benefit cell attachment and proliferation. It has been confirmed that keratin plays important roles in every stage of wound healing, including hemostasis, inflammation, proliferation, and remodeling, making keratin-based materials good candidates for wound dressings. In combination with synthetic and natural polymers, keratin-based wound dressings in the forms of films, hydrogels, and nanofibers can be achieved with improved mechanical properties. This review focuses on the recent development of keratin-based wound dressings. Firstly, the physicochemical and biological properties of keratin, are systematically discussed. Secondly, the role of keratin in wound healing is proposed. Thirdly, the applications of keratin-based wound dressings are summarized, in terms of the forms and functionalization. Finally, the current challenges and future development of keratin-based wound dressings are presented.

Rational design of MnO2@MnO2 hierarchical nanomaterials and their catalytic activities.

Hierarchically structured materials have special properties and possess potential in applications in the catalytic and electrochemical fields. Herein, two kinds of hierarchical core-shell nanostructures, lavender-like α-MnO2@α-MnO2 and balsam pear-like α-MnO2@γ-MnO2, were prepared by a facile room-temperature method using α-MnO2 nanowires as a backbone under acidic and alkaline conditions, respectively. When being used as a catalyst for dimethyl ether combustion, α-MnO2@γ-MnO2 exhibited a better performance than α-MnO2@α-MnO2 (T10 = 171 vs. 196 °C; T90 = 220 vs. 258 °C, SV = 30, 000 mL g-1 h-1). It is concluded that the larger surface area, higher reducibility/oxygen mobility, richer surface oxygen species, and the relatively smaller apparent activation energy are responsible for the superior performance of α-MnO2@γ-MnO2.

The vertical distribution of bacterial and archaeal communities in the water and sediment of Lake Taihu.

This study was conducted to characterize the vertical distribution of bacterial and archaeal communities in the water and sediment of Lake Taihu, which underwent a change in trophic status from oligotrophic to hypertrophic in last half of the 20th century. The results revealed that the bacterial communities in different layers of sediment sample were very similar, and were related to Alpha-, Beta-, Gamma- and Deltaproteobacteria, Nitrospira, Bacteroidetes, Firmicutes, Gemmatimonadetes, Verrucomicrobia, Chlorobi, Actinobacteria and Acidobacteria. In contrast, the archaeal communities varied greatly with depth. The archaeal communities were primarily related to Euryarchaeota and Crenarchaeota, with methanogenic Archaea accounting for approximately 2-35% of the total Archaea. Additionally, sequences related to putative ammonia-oxidizing Archaea and ammonia-oxidizing Bacteria were detected in different layers of sediment samples. The abundance of Archaea, Bacteria, methanogenic Archaea and Nitrospira was further characterized by real-time PCR.

Bacterial community composition of a shallow hypertrophic freshwater lake in China, revealed by 16S rRNA gene sequences.

The phylogenetic composition of a bacterial community from a hypertrophic freshwater lake in China was investigated by sequencing cloned 16S rRNA genes. Three hundred and thirty-six bacterial clones from four clone libraries in different months (March, May, July and September in 2004) were classified into 142 operational taxonomic units, most of which were affiliated with bacterial divisions commonly found in freshwater ecosystem, e.g. Alpha-, Beta-, Gamma- and Deltaproteobacteria, Bacteriodetes and Actinobacteria. The results showed that the composition of bacterial community in the July library was the most diverse one. Actinobacteria was the most significant lineage in Lake Taihu, with dominant numbers of operational taxonomic units in the May, July and September libraries. Phylogenetic analysis suggested that 53 sequences were grouped into six novel clusters which may represent specific populations indigenous to the environment. Coverage analyses indicated that the clone libraries could provide a fine inventory of bacterial diversity in the lake.