A hydrogel dressing with tunable critical temperature and photothermal modulating melittin release for multiply antibacterial treatment.

It is imperative to develop an antibiotic-free and long-term effective strategy for treating chronic wound infections due to the long-term utilization of antibiotics easily causing drug resistance. Herein, we fabricated a novel poly-N-isopropylacrylamide (PNIPAM)/polyacrylamide (PAM) coupling thermosensitive hydrogel integrating 1D lysozyme nanofiber doped with CuS nanoparticles (CuS/PP) and loading antibacterial peptide melittin (M) (CuS/PP-M) for combating chronic wound infection via photothermal modulating the release of melittin. For the CuS/PP-M hydrogel, the copolymerization of PNIPAM and PAM allows the lower critical solution temperature (LCST) higher than the body temperature, effectively hindering the spontaneous release of melittin when contacts the infected wound, while the integration of LNF/CuS nanofibers provides a stable photothermal treatment for triggering the release of melittin. As a result, the CuS/PP-M hydrogel exhibits synergistically enhanced effect on killing both Gram-positive and Gram-negative bacteria, which maintains more than 99 % bactericidal efficiency, even displays a long-term and multiply antibacterial performance by photothermal modulating melittin release. Moreover, the CuS/PP-M hydrogel presents both high antibacterial activity and excellent wound healing performance in the mouse wound model, thereby benefiting the chronic wound healing.

Multifunctionalized alginate/polydopamine cryogel for hemostasis, antibacteria and promotion of wound healing.

Hemostasis and anti-infection are crucial for emergency treatment of severe trauma. Developing functional biomaterial with efficient hemostasis, antibacterial activity and wound healing is of great social significance and clinical value to fast stop bleeding and save lives, but it is still challenged. Here we designed a series of multifunctionalized SA/PDA cryogels by using two-step cross-linking of dopamine and sodium alginate. The resulting interpenetrating network structure had good swelling ratio, excellent mechanical and shape memory properties. Compared with cotton gauze and gelatin sponge, the cryogels exhibited excellent activation of coagulation cascade, more blood cells and platelet adhesion. Due to the action of polydopamine, the cryogel also showed good antioxidant activity and photothermal antibacterial ability assisted by near-infrared radiation, as well as better wound healing performance than gelatin sponge and Tegaderm™ film. Moreover, in the tests of mouse tail docking model, rat femoral artery hemostasis model and non-compressible rabbit liver defect model, the treatment by SA/PDA cryogels presented less blood loss and shorter hemostasis time than cotton gauze and gelatin sponge. Therefore, SA/PDA cryogels with simple preparation process, low cost, and good biocompatibility would be applied in the variety of great clinical applications in bleeding control, anti-infection and wound healing, etc.

Preparation and Characterization of a Novel Triple Composite Scaffold Containing Silk Fiborin, Chitosan, and Alginate for 3D Culture of Colonic Carcinoma Cells In Vitro.

BACKGROUND Three-dimensional (3D) cell-culture scaffolds are ideal in vitro models to bridge the gap between two-dimensional cell culture in vitro and in vivo cancer models. Construction of 3D scaffolds using two kinds of biomaterials has been reported, but there are still many defects. To improve the performance of the scaffolds for 3D cell culture of colonic carcinoma (CC) cells in vitro, we attempted to construct triple composite scaffolds using silk fibroin (SF), chitosan (Cs), and alginate (Alg). MATERIAL AND METHODS We explored the suitability of triple composite scaffolds of SF/Cs/Alg at ratios of 1: 1: 0.5, 1: 1: 1, and 1: 1: 2 for 3D culture of CC cells, and used the dual composite scaffold of SF/Cs (1: 1) as a control group. We analyzed the physicochemical characteristics of these scaffolds and studied cell adhesion, cell proliferation, migration, colony-forming ability, microstructure and ultrastructure, and spheroid-forming capacity of the commercially available CC cell line HCT-116 on the prepared scaffolds. RESULTS Our results show that SF/Cs/Alg (1: 1: 1) scaffolds demonstrated the best profile, the highest uniform porosity and connectivity, and excellent hydroscopicity, and also exhibited appropriate and controlled swelling and degradation characteristics. The adhesion, proliferation, colony-forming, and wound-healing assays, green fluorescent protein-labeled HCT116 cell imaging, 4',6-diamidino-2-phenylindole and DY-554-phalloidin staining, scanning electron microscopy, and haematoxylin and eosin staining revealed that the triple composite scaffolds of SF/CS/Alg (1: 1: 1) supported cell adhesion, proliferation, migration, colony-forming ability, and spheroid formation far better than the dual composite scaffold of SF/CS (1: 1). CONCLUSIONS This study successfully demonstrated the potential of SF/Cs/Alg (1: 1: 1) scaffold as an alternative for the 3D in vitro culture of CC cells.