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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