While silver nanoparticles are widely used to endow materials with antibacterial activity, silver nanowires (AgNWs) have not attracted much attention. Herein, the composites of bacterial cellulose (BC) and AgNWs were prepared through a novel step-by-step in situ biosynthesis which retains the three-dimensional network of BC. The results of water vapor permeability, water uptake rate, and water retention rate showed that the BC/AgNW wound dressings could absorb wound skin exudates and maintain moisture environments. Furthermore, the BC/ AgNW dressings were robust and stretchable. More importantly, the BC/AgNW dressings exhibited sustained release of Ag +. The results from animal tests indicated that the BC/AgNW dressing with 38.4 wt% AgNWs exhibited higher expression levels of cytokeratin-10 and integrin-β4, greater proliferation of keratinocytes and formation of epithelial tissues and greatly improved skin regeneration over the bare BC. We propose that the integrated nanofibrous structure and the excellent and sustained antibacterial activity of AgNWs are responsible for the excellent in vivo wound healing ability and biocompatibility. These results suggest that the BC/AgNW composites have promising application as wound dressings.

A novel small-diameter graft consisting of nanofibrous bacterial cellulose and submicrofibrous cellulose acetate was prepared and evaluated in vitro and in vivo.

Constructing biomimetic structure and immobilizing antithrombus factors are two effective methods to ensure rapid endothelialization and long-term anticoagulation for small-diameter vascular grafts. However, few literatures are available regarding simultaneous implementation of these two strategies. Herein, a nano-micro-fibrous biomimetic graft with a heparin coating was prepared via a step-by-step in situ biosynthesis method to improve potential endothelialization and anticoagulation. The 4-mm-diameter tubular graft consists of electrospun cellulose acetate (CA) microfibers and entangled bacterial nanocellulose (BNC) nanofibers with heparin coating on dual fibers. The hybridized and heparinized graft possesses suitable pore structure that facilitates endothelia cells adhesion and proliferation but prevents infiltration of fibrous tissue and blood leakage. In addition, it shows higher mechanical properties than those of bare CA and hybridized CA/BNC grafts, which match well with native blood vessels. Moreover, this dually modified graft exhibits improved blood compatibility and endothelialization over the counterparts without hybridization or heparinization according to the testing results of platelet adhesion, cell morphology, and protein expression of von Willebrand Factor. This novel graft with dual modifications shows promising as a new small-diameter vascular graft. This study provides a guidance for promoting endothelialization and blood compatibility by dual modifications of biomimetic structure and immobilized bioactive molecules.

Dextrins are low-molecular-weight carbohydrates produced by partial hydrolysis of glycogen or starch achieved by applying dry heat under acidic conditions (pyrolysis or roasting) and/or using enzymes (amylases), malting or mashing. Dextrin is thus a glucose-containing saccharide polymer having the same general formula of starch, but smaller and less complex. Depending on the source and on how it is digested, it can exhibit different structural features (linear, branched, or cyclic) and properties such as hygroscopicity, fermentability, sweetness, stability, gelation, solubility, bioavailability, and molecular compositions. Among starch-derived materials, dextrin is widely used in a variety of applications, namely, adhesives in the manufacture of gummed tapes, textiles and paper, as moisturizing component in cosmetics, or in the food industry. However, its biocompatibility and biodegradability combined with its low cost, abundance, and availability in medical grade make dextrin an excellent polymer for biomedical applications. In this entry, we present an overview of biomedical applications of linear dextrins. The potential of dextrin as tissue engineering scaffolds, hydrogels, drug delivery systems, excipient in tablets, or nanomedicines are thoroughly discussed in this entry. 2636 Dextrin Devices-Drug Delivery: Gastro Dextrin Devices-Drug Delivery: Gastro

BACKGROUND Most of the current materials used in food packaging are synthetic and non‐degradable, raising environmental issues derived from the accumulation of plastics in landfills/waterways. The food industry increasingly needs eco‐friendly sustainable materials that meet food‐packaging requirements. Bacterial nanocellulose (BNC), a biopolymer obtained by fermentation, offers very good mechanical properties and the ability to carry and deliver active substances. However, its water‐vapor permeability is too high for food‐packaging applications. In this work, a layered biodegradable composite based on BNC and polyhydroxyalkanoate (PHBV) was produced, attempting to improve its overall barrier properties. Polyhydroxyalkanoate is a biopolymer with high degree of hydrophobicity and biodegradability, and is also obtained by fermentation. Wet BNC membranes produced by static culture were plasticized by impregnation of solutions of either glycerol (BNCgly) or polyethylene glycol (MW600) (BNCPEG). The plasticized BNC was then coated with PHBV solution dissolved in formic acid, and oven dried at 148 °C. RESULTS Overall, PHBV coating on plasticized BNC reduced water vapor permeability significantly (from 0.990 to 0.032 g.μm.m−2.day−1.Pa−1) under 50% relative humidity. It increased the hydrophobicity (contact angle from 10–40° to 80–90°) but decreased the stiffness (from 3.1 GPa to 1.3 Gpa) of the composite. CONCLUSIONS Overall, the mechanical and barrier properties of the layered composite obtained were considered suitable for food‐packaging applications. The plasticizing (with glycerol or polyethylene glycol) of BNC significantly improved the mechanical performance and the PHBV coating reduced the water affinity (vapor and liquid state) on BNC. © 2022 Society of Chemical Industry.