Plant mucus-derived microgels: Blood-triggered gelation and strong hemostatic adhesion.

Arrest of bleeding usually applies clotting agents to trigger coagulation procedures or adhesives to interrupt blood flow through sealing the vessel; however, the efficiency is compromised. Here, we propose a concept of integration of hemostasis and adhesion via yam mucus's microgels. The mucus microgels exhibit attractive attributes of hydrogel with uniform size and shape. Their shear-thinning, self-healing and strong adhesion make them feasible as injectable bioadhesion. Exceptionally, the blood can trigger the microgels' gelation with the outcome of super extensibility, which leads to the microgels a strong hemostatic agent. We also found a tight gel adhesive layer formed upon microgels' contacting the blood on the tissue, where there is the coagulation factor XIII triggered to form a dense three-dimensional fibrin meshwork. The generated structures show that the microgels look like hard balls in the dispersed phase into the blood-produced fibrin mesh of a soft net phase. Both phases work together for a super-extension gel. We demonstrated the microgels' fast adhesion and hemostasis in the livers and hearts of rabbits and mini pigs. The microgels also promoted wound healing with good biocompatibility and biodegradability.

Biosynthetic Plastics as Tunable Elastic and Visible Stent with Shape-Memory to Treat Biliary Stricture.

Common biliary tract is ≈4 mm in diameter to deliver bile from liver to small intestine to help digestion. The abnormal narrowing leads to severe symptoms such as pain and nausea. Stents are an effective treatment. Compared with non-degradable stents which require repeated removal, biodegradable stents have the advantage of reducing secondary injury related to endoscopic operation and patient burden. However, current biodegradable materials may cause tissue hyperplasia and the treatment method does not target etiology of stricture. So recurrence rates after biodegradable stent implantation are still high. Here, a biodegradable helical stent fabricated from biosynthetic P(3HB-co-4HB) is reported. Tunable properties can be acquired through altering culture substrates. Stent shows shape memory in various solvents. The stent has an optimized design with helical structure and outer track. The self-expanding of helical structure and double drainage realized by outer track greatly improve drainage of bile. Importantly, stent-loading triamcinolone acetonide can inhibit proliferation of fibroblasts and reduce incidence of restricture. Therapeutic effect is also demonstrated in minipigs with biliary stricture. The results of minipig experiments show that biliary duct in treatment group is unobstructed and tissue hyperplasia is effectively inhibited.

Endoscopy Deliverable and Mushroom-Cap-Inspired Hyperboloid-Shaped Drug-Laden Bioadhesive Hydrogel for Stomach Perforation Repair.

Gastrointestinal tract perforation is a full-thickness injury that causes bleeding and fatal infection of the peritoneum. This condition worsens in an acidic gastric environment which interferes with the normal coagulation cascade. Current endoscopic clips to repair gastric perforations are ineffective, and metal or plastic occluders need secondary surgery to remove them. Herein, we report a self-expandable, endoscopy deliverable, adhesive hydrogel to block gastric perforation. We found the nanosilica coating significantly enhanced the adhesive strength even under a simulated strong acidic stomach environment. The developed device was disulfide cross-linked for the reducible degraded gel. By loading with vonoprazan fumarate (VF) and acidic fibroblast growth factor (AFGF), the hyperboloid-shaped device can have a sustained drug release to regulate intragastric pH and promote wound healing. The gel device can be compressed and then expanded like a mushroom when applied in an acute gastric perforation model in both rabbits and minipigs. By utilizing a stomach capsule robot for remotely monitoring the pH and by immunohistochemical analysis, we demonstrated that the compressible hyperboloid-shaped gel could stably block the perforation and promoted wound healing during the 28 days of observation. The real-time pH meter demonstrated that the gel could control intragastric pH above 4 for nearly 60 h to prevent bleeding.

Aligned nanofibrous collagen membranes from fish swim bladder as a tough and acid-resistant suture for pH-regulated stomach perforation and tendon rupture.

BACKGROUND: Wound closure in the complex body environment places higher requirements on suture's mechanical and biological performance. In the scenario of frequent mechanical gastric motility and extremely low pH, single functional sutures have limitations in dealing with stomach bleeding trauma where the normal healing will get deteriorated in acid. It necessitates to advance suture, which can regulate wounds, resist acid and intelligently sense stomach pH. METHODS: Based on fish swim bladder, a double-stranded drug-loaded suture was fabricated. Its cytotoxicity, histocompatibility, mechanical properties, acid resistance and multiple functions were verified. Also, suture's performance suturing gastric wounds and Achilles tendon was verified in an in vivo model. RESULTS: By investigating the swim bladder's multi-scale structure, the aligned tough collagen fibrous membrane can resist high hydrostatic pressure. We report that the multi-functional sutures on the twisted and aligned collagen fibers have acid resistance and low tissue reaction. Working with an implantable "capsule robot", the smart suture can inhibit gastric acid secretion, curb the prolonged stomach bleeding and monitor real-time pH changes in rabbits and pigs. The suture can promote stomach healing and is strong enough to stitch the fractured Achilles tendon. CONCLUSIONS: As a drug-loaded absorbable suture, the suture shows excellent performance and good application prospect in clinical work.