A bioinspired injectable antioxidant hydrogel for prevention of postoperative adhesion.

Postoperative adhesions, a prevalent complication following abdominal surgery, affect 90% of patients undergoing abdominal surgical procedures. Currently, the primary approach to prevent postoperative adhesions involves physical isolation of the surgical site and surrounding tissues using a hydrogel; however, this method represents a rudimentary strategy. Herein, considering the impact of oxidative stress and free radicals on postoperative adhesion during wound healing, an injectable antioxidant hydrogel, named PU-OHA-D, was successfully synthesized, which is formed by the crosslinking of dopamine-modified oxidized hyaluronic acid (OHA-D) and dihydrazide-terminated polyurethane (PU-ADH) through hydrazone bonding. PU-OHA-D hydrogel possesses versatile characteristics such as rapid gel formation, injectability, self-repair capability and biodegradability. Additionally, they exhibit an excellent ability to clear free radicals and superior tissue adhesion. PU-OHA-D can be injected in situ to form a hydrogel to prevent abdominal wall-cecum adhesion. Importantly, it can effectively eliminate free radicals and inhibit oxidative stress at the wound site. Thereby, it leads to collagen physiological degradation and prevents the occurrence of postoperative adhesions. The bioinspired hydrogel demonstrates its great potential in preventing postoperative adhesion and promoting wound healing.

Polypropylene composite mesh modified by polyurethane gel with ROS scavenging and anti-inflammatory effects for pelvic floor repair.

Development of an inflammation modulating polypropylene (PP) mesh in pelvic floor repair is an urgent clinical need. This is because PP mesh for pelvic floor repair can cause a series of complications related to foreign body reactions (FBR) in postoperative period. Therefore, we successfully prepared PP composite mesh that can scavenge reactive oxygen species (ROS) and inhibit inflammation to moderate FBR by a simple method. First, a pregel layer was formed on PP mesh by dip coating. Among them, polyurethane with polythioketal (PTK) is an excellent ROS scavenger, and dopamine methacrylamide (DMA) improves the stability of the coating and synergistically scavenges ROS. Then, a composite mesh (optimal PU50-PP) was obtained by photopolymerization. The results showed that the polyurethane gel layer was able to scavenge more than 90% of free radicals and about 75% of intracellular ROS. In vitro, PU50-PP mesh significantly scavenged ROS and resisted macrophage adhesion. After implantation in the posterior vaginal wall of rats, PU50-PP eliminated 53% of ROS, inhibited inflammation (decreased IL-6, increased IL-10), and dramatically reduced collagen deposition by about 64%, compared to PP mesh. Thus, the composite PP mesh with ROS scavenging and anti-inflammatory properties provides a promising approach for mitigating FBR.

Modified ammonium persulfate oxidations for efficient preparation of carboxylated cellulose nanocrystals.

Ammonium persulfate (APS) was able to produce carboxylated cellulose nanocrystals (CNCs-COOH) directly from the raw materials of cellulose. However, the industrial production of CNCs-COOH by this method is obstructed by the lower preparation efficiency. Herein, by the activation via N,N,N',N'-tetramethylethylenediamine (TMEDA) and ultrasonic assisted disintegration, modified APS method to extract CNCs-COOH from pulp was presented. A high yield (up to 62.5 %), low usage of APS (8.5 g APS per gram pulp) and less reaction time (6 h) was achieved. The as-prepared CNCs-COOH exhibited high carboxyl group content (1.45 mmol/g) and high crystallinity index of 93 %. The reaction mechanism has been studied, and the results show that with the addition of TMEDA, S2O82-can be converted to free radicals and hydrogen peroxide more quickly. Our studies suggested that modified APS method may be a suitable and economic alternative for the preparation of CNCs-COOH.