In this study, we report the preparation of a novel microcapsule of ~ 100 μm with a liquid (as compared to solid-like alginate hydrogel) core and an alginate-chitosan-alginate (ACA) shell for encapsulation and culture of embryonic stem (ES) cells in the miniaturized 3D space of the liquid core. Murine R1 ES cells cultured in the microcapsules were found to survive (> 90%) well and proliferate to form either a single aggregate of pluripotent cells or embryoid body (EB) of more differentiated cells in each microcapsule within 7 days, dependent on the culture medium used. This novel microcapsule technology allows massive production of the cell aggregates or EBs of uniform size and controllable pluripotency, which is important for the practical application of stem cell based therapy. Moreover, the semipermeable ACA shell was found to significantly reduce immunoglobulin G (IgG) binding to the encapsulated cells by up to 8.2 times, compared to non-encapsulated cardiac fibroblasts, mesenchymal stem cells, and ES cells. This reduction should minimize inflammatory and immune responses induced damage to the cells implanted in vivo becasue IgG binding is an important first step of the undesired host responses. Therefore, the ACA microcapsule with selective shell permeability should be of importance to advance the emerging cell-based medicine.
The design of an environmentally benign cost-effective adsorbent for superfast removal of phosphate from wastewater is vital but remains a huge challenge.
In recent years, tremendous efforts have been dedicated to developing wood‐derived functional polymeric materials due to their distinctive properties, including environmental friendliness, renewability, and biodegradability. Thus, the uniqueness of the main components in wood (cellulose and lignin) has attracted enormous interest for both fundamental research and practical applications. Herein, the emerging field of wood‐derived functional polymeric materials fabricated by means of macromolecular engineering is reviewed, covering the basic structures and properties of the main components, the design principle to utilize these main components, and the resulting wood‐derived functional polymeric materials in terms of elastomers, hydrogels, aerogels, and nanoparticles. In detail, the natural features of wood components and their significant roles in the fabrication of materials are emphasized. Furthermore, the utilization of controlled/living polymerization, click chemistry, dynamic bonds chemistry, etc., for the modification is specifically discussed from the perspective of molecular design, together with their sequential assembly into different morphologies. The functionalities of wood‐derived polymeric materials are mainly focused on self‐healing and shape‐memory abilities, adsorption, conduction, etc. Finally, the main challenges of wood‐derived functional polymeric materials fabricated by macromolecular engineering are presented, as well as the potential solutions or directions to develop green and scalable wood‐derived functional polymeric materials.
Effective utilization of abundant industrial lignin has growingly attracted much attention besides potential environmental issues. Although chemical graft polymerization modification is one facile strategy for extending its applications, it remains an intractable challenge to select a highly efficient initiation system. We herein have attempt to understand the CaCl 2 − H 2 O 2 system in initiating the graft polymerization of acrylic monomers onto acetic acid lignin (AAL) and biobutanol lignin (BBL). The initiation system is found to be highly efficient and selective, as proved by the successful graft of polyacrylates onto them, and a possible mechanism is also proposed. Thermal analysis shows that the graft modification results in a higher glass transition temperature and higher thermal stability of lignin. The graft modification make both AAL and BBL become more hydrophobic than before modification. Moreover, adding a small amount of lignin-graf t-polyacrylate can considerably improve the UV blocking capability in addition to the reinforcing effect on polylactic acid. This work offers a novel, highly effective, and selective free radical initiation system for functionalizing lignin.
The development of flexible conductive elastomers integrating renewable feedstock, splendid mechanical property, and excellent weather resistance is of major interest and challenge. Here, a novel strategy is reported to construct the liquid‐free cellulose‐derived ionic conductive elastomer that is successfully applied in the wearable sensor and triboelectric nanogenerators (TENG). In this strategy, the ionic conductive elastomer with physical and chemical dual‐crosslinking network is prepared via in situ polymerization of the polymerizable deep eutectic solvent. The construction of dual‐crosslinking network improves the mechanical strength and toughness more than 2 times, and the cellulose contributes to forming the dense hydrogen bond crosslinking network that can improve the recyclability, anti‐freezing, and solvent‐resistance performance. Benefiting from these features, the ionic conductive elastomer is successfully applied in the wearable sensors and TENG for monitoring human motion, and in harvesting mechanical energy to convert into stable electrical outputs to light the LEDs, charge the capacitor, and power the electronic watch. The ionic conductive elastomer maintains reliable sensing and energy harvesting performance even after recycling, soaking in organic solvent, or at low/high temperature. This study paves a promising strategy for fabricating sustainable and multifunction flexible electronics that are suitable for harsh environments.
Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community-settings, resulting in increased mortality rates and hospitalization costs. Emergence of resistance even to vancomycin, the standard reference for MRSA treatment, builds up pressure for the search of novel alternatives. We report potent natural resin acid-based cationic antimicrobial compounds and polymers that exhibit surprising antimicrobial activity against a range of MRSA strains, yet are largely non-toxic against mammalian cells.Molecular dynamics simulations and dye-leakage assays with anionic phospholipid membrane mimics of bacteria demonstrate a membrane-lysing effect induced by unique fused ring structures of resin acids that may constitute the principal mechanism of action for selective lysis of bacterial cells over mammalian cells. Our antimicrobial materials are derived from an unlikely yet abundant natural source, and offer a novel alternative to currently-used approaches.
Efficiently converting biomass into multifunctional polymerized materials is a challenge to effect high‐valued utilization of biomass resources. A two‐step 3 D‐printing approach has been developed to fabricate a class of robust, fluorescent shape‐memory thermosets from cellulose and rosin‐based photosensitive 3 D‐printing resin solution. The stereolithography 3 D printing was first performed to form the first crosslinked network by UV‐induced chain‐growth polymerization, which fixed the shape of thermoset. Subsequently, isocyanate was applied to react with hydroxy in the monomer to form the second crosslinked network by thermally induced step‐growth polymerization. The formation of a dual‐cure network, leading to phase separation and increased crosslinking density, could greatly improve the mechanical and thermal properties of 3 D‐printed thermosets and endow them with thermally triggered shape‐memory properties and excellent repairability. The 3 D‐printed thermosets are found to have strong luminescence resulting from aggregation‐induced emission originating from rosin. In addition, these 3 D‐printed thermosets could degrade in the presence of NaOH aqueous solution and in situ achieved a range of flexible conductive hydrogels that have important potential application in the flexible electronic materials and smart photoelectric materials.
Removing phosphate ions from eutrophic waters is of paramount importance; however, the design of low-cost, high-performance adsorbents for phosphorus removal has remained a huge challenge. Herein, we have demonstrated the fabrication of a low-cost, eco-friendly absorbent, LPC@La(OH)3, by loading lanthanum hydroxide nanorods within lignin-derived porous carbon for superfast and highly efficient phosphorus removal. As-prepared LPC@La(OH)3 exhibits a high adsorption capacity of 60.24 mg P L–1 and a high lanthanum usage efficiency. Our results show an ultrafast removal of up to 99.5% phosphate in 10 min when the initial concentration is 2 mg P L–1. Moreover, LPC@La(OH)3 can efficiently reduce the phosphate concentration to meet the below U.S. Environmental Protection Agency limits (50 μg P L–1) for eutrophication prevention. More importantly, it shows a high phosphate absorption ability over the wide range of pH 3–7, in addition to a high adsorption selectivity toward phosphate and high stability during adsorption process. Both the chemical precipitation and the ligand exchange are mainly responsible for the phosphate removal by LPC@La(OH)3. As-designed lignin-derived, ecofriendly, high-performance LPC@La(OH)3 shows enormous potential for the phosphate removal from both municipal wastewater and industrial effluents.
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