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.

Materials Selection and Scaffold Construction for Liver Tissue Engineering

To design the scaffold with suitable properties for the development of tissue engineered livers, materials design, selection and scaffold construct are three dispensable steps to be followed consequently. Firstly, some natural materials such as collagen, chitosan and alignate as well as some prevailing aliphatic polyester such as poly(lactic acid) (PLA), polyglycolide (PGA) and their copolymers poly(lactide-co-glycolide) (PLGA) are selected and characterized by hepatocyte culture. The experimental results reveal that the natural materials with excellent biocompatibility are not suitable as the scaffold alone because of the poor mechanical properties. At same time, aliphatic polyesters with good mechanical properties and biodegrade abilities are also proved inapplicable for hepatocytes for the lack of right cell recognition sites. Among our study scope, the hybrid materials such as collagen/chitosan or collagen/chitosan/heparin are the very promising candidates for hepatic tissue engineering scaffold. Secondly, two novel designs composed of collagen and PLGA, namely, the spindle porous scaffold with separated channels for transportation of nutrient, plasma and the one made by dewaxen-casting method are initiated respectively.