Expansion-clotting chitosan fabrics based on unidirectional fast-absorption fibers for rapid hemorrhage control.

The rapid absorption of water from the blood to concentrate erythrocytes and platelets, thus triggering quick closure, is important for hemostasis. Herein, expansion-clotting chitosan fabrics are designed and fabricated by ring spinning of polylactic acid (PLA) filaments as the core layer and highly hydrophilic carboxyethyl chitosan (CECS) fibers as the sheath layer, and subsequent knitting of obtained PLA@CECS core spun yarns. Due to the unidirectional fast-absorption capacity of CECS fibers, the chitosan fabrics can achieve erythrocytes and platelets aggregate quickly by concentrating blood, thus promoting the formation of blood clots. Furthermore, the loop structure of coils formed in the knitted fabric can help them to expand by absorbing water to close their pores, providing effective sealing for bleeding. Besides, They have enough mechanical properties, anti-penetrating ability, and good tissue-adhesion ability in wet conditions, which can form a physical barrier to resist blood pressure during hemostasis and prevent them from falling off the wound, thus enhancing hemostasis synergistically. Therefore, the fabrics exhibit superior hemostatic performance in the rabbit liver, spleen, and femoral artery puncture injury model compared to the gauze group. This chitosan fabric is a promising hemostatic material for hemorrhage control.

Hyaluronic acid hydrogels with excellent self-healing capacity and photo-enhanced mechanical properties for wound healing.

A continuously stable moist healing environment is immensely beneficial for wound healing, which can be availably achieved by providing an in situ hydrogel with enough strength resembling skin tissue and self-healing ability. Herein, through a dual-crosslinking strategy, hyaluronic acid-based hydrogels with excellent self-healing capacity and enhanced mechanical properties are fabricated via the acylhydrazone linkages and subsequent photocrosslinking based on hydrazide-modified sodium hyaluronate and aldehyde-modified maleic sodium hyaluronate. The hydrogels demonstrate the fast gelation process (< 1 min), the controlled swelling behaviors, and the good biocompatibility. Notably, they possess enhanced mechanical strength similar to the human dermis (∼ 2.2 kPa). Also, they can self-heal rapidly with a self-healing efficiency of ∼90 % at 6 h. Based on this, the hyaluronic acid-based hydrogels, without any biological factors involved, can facilitate the full-thickness skin wound reconstruction process by accelerating the three phases of the wound repair, including reducing wound inflammation in the inflammatory phase, promoting angiogenesis in the proliferative phase, and promoting the deposition and reconstruction of collagen in the remodeling phase. The produced hyaluronic acid hydrogel can serve as an ideal candidate for wound healing.

Antibacterial hyaluronic acid hydrogels with enhanced self-healing properties via multiple dynamic bond crosslinking.

The self-healing hydrogel offering intrinsic antibacterial activity is often required for the treatment of wounds because it can provide effective wound protection and prevent wound infection. Herein, antibacterial hyaluronic acid hydrogels with enhanced self-healing performances are prepared by multiple dynamic-bond crosslinking between aldehyde hyaluronic acid, 3, 3'- dithiobis (propionyl hydrazide) and fungal-sourced quaternized chitosan. Due to the formation of these different types of reversible interactions e.g. hydrazone bonds, disulfide bonds, and electrostatic interactions, the hyaluronic acid hydrogels can gel rapidly and exhibit excellent self-healing ability, which can heal completely within 1 h. Furthermore, the hydrogels show good antibacterial activity against E. coli and S. aureus with an inhibition ratio of ~100 % and above 75 %, respectively. Additionally, the hydrogels are cytocompatible, which makes them the potential for biomedical applications e.g. cell culture, tissue engineering, and wound dressing.

Influence of geometric parameters on partial compressive force and pushing performance of flow diverter.

Research on flow diverter (FD) has progressed over the past decades; however, the relationships between parameters such as stent diameter, porosity, and number of wires and the properties of FDs, such as partial compressive force and push resistance, are not well understood. In this study, the partial compressive force and push resistance of braided FDs with varying porosity (61%-75%), diameter (2.5-5.0 mm), and number of wires (48 or 64) were evaluated using finite element analysis (FEA) and bench tests. At a small compression ratio, the 48-wire stents exhibited a larger partial compressive force than 64-wire stents of the same diameter. But when the compression ratio was 50%, the 64-wire stents had better resistance to pressure. The partial compressive force decreased as the stent diameter increased when all other parameters were equal. However, the influence of the diameter decreased as the stent porosity increased. The push resistance decreased as the porosity and diameter increased, and increased with the number of wires. These results provide useful information for FD design. Decreasing the number of wires can reduce the push resistance, while the push resistance is mainly influenced by the porosity and number of wires, and almost has no relationship with the partial compressive force. The FEA model proved very reliable, and corresponded well to the bench test results, which indicates that this model can be utilized to guide the design of FDs.