No abstract

Bio-based slow-release fertilizers (SRFs) have drawn significant attention because their applications for crop production can improve nutrient utilization efficiency as well as prevent environmental pollution. However, current commercial SRFs still exhibit uncontrollable release patterns, use a large quantity of synthetic coating materials, and are unable to adapt to complex soil conditions (e.g., arid soil). In this study, a double-layer SRF was formulated from a low-cost lignin−clay nanohybrid composite to not only achieve controllable and slow nitrogen fertilizer release but also improve the water-holding property. The low-cost and hydrophobic lignin−clay nanohybrid was cross-linked with bio-based alginate to prepare the core-layer material, followed by a coating process using a highly water-absorbent polymer poly(acrylic acid) (PAA) to achieve a double-layer SRF. We examined the chemical structures, urea release rates, and water-holding capacities of the double-layer PAA−lignin−clay nanohybrid composite coated SRF (PLC-SRF). The results showed that PLC-SRF released 13−40% less urea and absorbed 23% more water than SRFs coated with only alginate. Its urea release rate is slower than that of previously reported SRFs using other materials. This nanocomposite coating material has great potential for producing a new type of bio-based SRFs that are beneficial to sustainable crop production.

Antimicrobial peptides (AMPs) are significant components of the innate immune system and play indispensable roles in the resistance to bacterial infection. Here, we investigated the antimicrobial activity of lycosin-I, a 24-residue cationic anticancer peptide derived from Lycosa singorensis with high structural similarity to several cationic and amphiphilic antimicrobial peptides. The antimicrobial activity of lycosin-I against 27 strains of microbes including bacteria and fungi was examined and compared with that of the Xenopus-derived AMP magainin 2 using a microdilution assay. Lycosin-I inhibited the growth of most microorganisms at low micromolar concentrations, and was a more potent inhibitor than magainin 2. Lycosin-I showed rapid, selective and broad-spectrum bactericidal activity and a synergistic effect with traditional antibiotics. In vivo, it showed potent bactericidal activity in a mouse thigh infection model. High Mg2+ concentrations reduced the antibacterial effect of lycosin-I, implying that the peptide might directly interact with the bacterial cell membrane. Uptake of the fluorogenic dye SYTOX and changes in the surface of lycosin-Itreated bacterial cells observed by scanning electron microscopy confirmed that lycosin-I permeabilized the cell membrane, resulting in the rapid bactericidal effect. Taken together, our findings indicate that lycosin-I is a promising peptide with the potential for the development of novel antibacterial agents.

No abstract

Large amounts of food are wasted during the food supply chain. This loss is in part due to consumer confusion over dates on food packages that can indicate a variety of quality indicators in the product (e.g., expiration date, “best by” date, “sell by” dates, etc.). To reduce this food loss, much research has been focused on the films that offer simple and easily manipulated indication systems to detect food spoilage. However, these materials are usually hydrophilic biopolymers that can detect the food spoilage in a wide pH range but do not provide highly sensitive real-time measurements. In this work, a glycerol-based nanocomposite core–shell latex film was synthesized to create a responsive packaging material that can provide real-time pH detection of food with high sensitivity. First, the pH-responsive dendrimer comonomer was synthesized from glycerol and diamine. Then, the nanoencapsulation polymerization process via miniemulsion was conducted to form a core–shell structure with tunable nanoshell thickness for a sensible pH-responsive release (<0.5 pH change). Next, the flexible film encapsulated a color-indicative dye that provided highly sensitive and visible color changes as both the pH dropped and the time elapsed in the food. This film also provided a barrier to water and heat and resisted deformation. Ultimately, this nanocomposite flexible film pending a pH sensor has the potential as an intelligent food packaging material for a universal, accurate, easy-to-use, and real-time food spoilage monitoring system to reduce food waste.