The gut microbiota represents a large community of microorganisms that play an important role in immune regulation and maintenance of homeostasis. Living bacteria receive increasing interest as potential therapeutics for gut disorders, because they inhibit the colonization of pathogens and positively regulate the composition of bacteria in gut. However, these treatments are often accompanied by antibiotic administration targeting pathogens. In these cases, the efficacy of therapeutic bacteria is compromised by their susceptibility to antibiotics. Here, we demonstrate that a single-cell coating composed of tannic acids and ferric ions, referred to as ‘nanoarmor’, can protect bacteria from the action of antibiotics. The nanoarmor protects both Gram-positive and Gram-negative bacteria against six clinically relevant antibiotics. The multiple interactions between the nanoarmor and antibiotic molecules allow the antibiotics to be effectively absorbed onto the nanoarmor. Armored probiotics have shown the ability to colonize inside the gastrointestinal tracts of levofloxacin-treated rats, which significantly reduced antibiotic-associated diarrhea (AAD) resulting from the levofloxacin-treatment and improved some of the pre-inflammatory symptoms caused by AAD. This nanoarmor strategy represents a robust platform to enhance the potency of therapeutic bacteria in the gastrointestinal tracts of patients receiving antibiotics and to avoid the negative effects of antibiotics in the gastrointestinal tract.

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Realizing environmentally friendly polymers that could heal themselves at room temperature is an important challenge for sustainable societies. Herein, environment-friendly self-healing waterborne polyurethanes (WPUs) containing diselenide groups were synthesized. The healing efficiency could reach up to more than 90% after exposed to visible light for 48 hours and the fractured location was allowed to be healed repeatedly. Meanwhile, a fast room-temperature self-healing could also be achieved in 4 hours with a healing efficiency of~84%. The healing process was a combination of rapid closure of crack surfaces at the beginning due to the rebuilding of hydrogen bonds and gradual restoration of mechanical property derived from diselenide metathesis across the fractured interface. At the same time, room-temperature reprocessing could be also achieved with the aid of external pressure under visible light. Moreover, the prepared diselenide-containing WPUs exhibited excellent emulsion stability. The present work would be hopefully developed into a methodology of design and fabrication of environmentally friendly photo-sensitive polymers with self-healing and reprocessing abilities. covalent bonds, such as Diels-Alder bonds, 16 disulfide, 17,18 imine, 19 Schiff base, 20 diarylbibenzofuranone, 21 trithiocarbonate, 22 and boroxine, 23 and non-covalent bonds, such as hydrogen bond, 24 host-guest interactions, 12 and metal-ligand coordination bonds. 2 Generally, certain external stimulus are required in the intrinsic healing process, such as heat, 16 light, 25 ultrasound, 26 pH change, 27 redox, 28 and water, 29 and a certain time is needed to complete the healing process. However, most of these healing processes occur under harsh conditions, including high temperature, 15 oxygen-free, 22 ultrasound, 26 redox, 28 and pH change, 27,30 which restrict the wide application of these self-healing materials.Compared with the commonly used external stimuli for intrinsic self-healing, light is undoubtedly an attractive one because it is clean, cheap, and readily available, and the healing could be achieved in targeted position and remotely. [31][32][33][34][35] Light sources employed in the healing process including ultraviolet (UV) light, 25 visible light, 31,32 and infrared light. 33 UV light is the Additional Supporting Information may be found in the online version of this article.

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Collagen, the main component of mammal skin, has been traditionally used in leather manufacturing for thousands of years due to its diverse physicochemical properties. Collagen is the most abundant protein in mammals and the main component of the extracellular matrix (ECM). The properties of collagen also make it an ideal building block for the engineering of materials for a range of biomedical applications. Reproductive medicine, especially human fertility preservation strategies and reproductive organ regeneration, has attracted significant attention in recent years as it is key in resolving the growing social concern over aging populations worldwide. Collagen-based biomaterials such as collagen hydrogels, decellularized ECM (dECM), and bioengineering techniques including collagen-based 3D bioprinting have facilitated the engineering of reproductive tissues. This review summarizes the recent progress in applying collagen-based biomaterials in reproductive. Furthermore, we discuss the prospects of collagen-based materials for engineering artificial reproductive tissues, hormone replacement therapy, and reproductive organ reconstruction, aiming to inspire new thoughts and advancements in engineered reproductive tissues research. Graphical abstract

Herein, we synthesized a series of polyurethane copolymers (PUs) with poly(1,4-butylene adipate) glycol as soft segment and 2,4-toluene diisocyanate as well as extenders including 1,4-butanediol and di(1-hydroxyethylene) diselenide as hard segment. The chemical structure, thermal property, crystallization behavior, shape memory, and self-healing performances of the PUs were systematically characterized by a series of experiments. It was found that the PU2 containing a higher diselenide component (33 mol %) exhibited both shape memory and self-healing behaviors under a moderate temperature (57 8C). Meanwhile, the PUs showed a good repeatability of shape memory function, and their fixity and recovery ratios were all above 90%. Additionally, the dynamic exchangeable feature of diselenide bonding endues the PUs chains with an acceptable reprocessability and self-healing performances, and the PU2 sample could be healed for five times by thermal treatment with the healing efficiencies above 70%. This work provides a heuristic perspective for the development of shape memory and self-healing materials. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46326.

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