Water-driven noninvasively detachable wet tissue adhesives for wound closure.

Tissue adhesive with on-demand detachment feature is critically important since it can minimize hurt to patient when it is stripped away. Herein, a water-driven noninvasively detachable wet tissue adhesive hydrogel (w-TAgel) was produced by UV-initiated radical copolymerization of N-isopropylacrylamide (NIPAM), acrylamide (AAm), gelatin methacrylate (GelMA), and urushiol. As a w-TAgel, its robust and tough mechanical property makes it suitable for dynamic wound tissue. The polyurushiol segments of it are crucial to the formation of tough adhesion interface with various wet tissues, while polyNIPAM units play an indispensable role in on-demand detachment via thermo-responsive swelling behavior because the hydrophobic aggregation among isopropyl groups is destroyed upon water treatment with temperature of 25 â€‹°C or less. Additionally, it exhibits multiple merits including good hemocompatibility, cytocompatibility as well as pro-coagulant activity and hemostasis. Therefore, our w-TAgel with strong adhesion and facile detachment is an advanced prospective dressing for wound closure and rapid hemostasis. The wet tissue adhesion and water-driven detachable mechanism may shed new light on the development of on-demand noninvasively detachable wet tissue adhesives.

Catechol modification of non-woven chitosan gauze for enhanced hemostatic efficacy.

Development of efficient hemostatic gauze is critical to increasing survival rate by quick bleeding control of life-threatening hemorrhage. Herein, a novel chitosan non-woven hemostatic gauze is made by slightly surface modification with a special catechol compound, i.e. 3-(9,11,13-pentadecatrienyl)-1,2-benzenediol with a long side hydrophobic alkyl chain. Its wettability, interaction with red blood cell and platelet, and hemostatic efficacy on rat injuries are evaluated. This chitosan-catechol gauze demonstrates impressive hemostatic performances on rat femoral artery and liver laceration injury models (blood loss of this modified chitosan gauze is less than 17% of that of pristine chitosan gauze). Additionally, it is biodegradable, and maintains non-cytotoxicity. It integrates three structure and function effects together, i.e., anchoring effect between catechol and tissue, blood repelling effect from hydrophobic alkyl chain, and blood wicking effect from hydrophilic chitosan. Therefore, a new hemostatic mechanism is proposed for the excellent hemostatic potentials of this chitosan gauze.

Efficient, biosafe and tissue adhesive hemostatic cotton gauze with controlled balance of hydrophilicity and hydrophobicity.

Cotton gauze is a widely used topical hemostatic material for bleeding control, but its high blood absorption capacity tends to cause extra blood loss. Therefore, development of rapid hemostatic cotton gauze with less blood loss is of great significance. Here, we develop an efficient hemostatic cotton gauze whose surface is slightly modified with a catechol compound which features a flexible long hydrophobic alkyl chain terminated with a catechol group. Its hemostatic performance in animal injuries is superior to standard cotton gauze and Combat GauzeTM. Its biosafety is similar to cotton gauze and rebleeding hardly occurs when the gauze is removed. Here, we show its hemostatic capability is attributable to the rapid formation of big and thick primary erythrocyte clots, due to its effective controlling of blood movement through blocking effect from tissue adhesion by catechol, blood wicking in cotton, and the hydrophobic effect from long alkyl chains.

Bacterial Cellulose-Alginate Composite Beads as Yarrowia lipolytica Cell Carriers for Lactone Production.

The demand for natural lactone gamma-decalactone (GDL) has increased in the fields of food and cosmetic products. However, low productivity during bioprocessing limits its industrial production. In this study, a novel composite porous cell carrier, bacterial cellulose-alginate (BC-ALG), was used for long-term biotransformation and production of GDL. The effects of this carrier on biotransformation and related mechanisms were investigated. BC-ALG carriers showed improved mechanical strength over ALG carriers, with their internal embedded cell pattern changed to an interconnected porous structure. In five repeated-batch biotransformation experiments, the maximum concentration of GDL obtained in culture with BC-ALG carriers was 8.37 g/L, approximately 3.7 times higher than that from the medium with an ALG carrier alone. The result indicated that multiple hydrogen bonding interactions at the interface between BC and ALG contributed to the compatibility and stability of BC-ALG carriers. On the basis of the above results, the BC-ALG composite carrier can be considered ideal for immobilisation of cells for the production of GDL on an industrial scale, and has the potential to be utilised in other biological processes.