Preparation Of Carrageenan/agarose Composite Sponges And Their Immunomodulatory Activities Towards Macrophage

Recently,the treatment and recovery of skin disease caused by immune system deficiency and diabetic complication is a challenge to modern medicine.This kind of wound is hard to be healed due to the deficiency of immune response within the peripheral tissue,which could not be recovered through the stimulation of skin tissue by the immune system itself.Carrageenan is a kind of anion polysaccharide extracted from red seaweeds,composed of sulfate glactose as its sugar unit.It is a trigger agent for inflammation model,and plays an important role in the process of immune response and inflammation.Preparing biomaterials containing carrageenan component is a possible way to stimulate the immune system and to accelerate the wound healing.In this study,in order to solve the drawbacks in mechanical strength of carrageenan as biomedical material,three kinds(κ-、ι-,and λ-)of carrageenan/agarose(weight ratio=1:1)composite sponges were prepared through the blending and freeze-drying methods with purified carrageenan.The sponges showed cellular pore structure under the observation of the scanning electronic microscope.The tenacities of the three kinds of carrageenan/agarose composite sponges were higher than the pure carrageenan sponge,and the water absorption rate reached to 1600%.Additionally,since both the carrageenan and agarose could reach a sol-gel equilibrium at human physiological environment,the composite sponges could release carrageenan slowly,and further generate immunostimulatory activity to macrophages.In the dissolution and release test of carrageenan,three composite sponges could release carrageenan slowly and constantly,among which λ-carrageenan/agarose composite sponge showed the highest release amount of carrageenan,with 42.0% within 24 h.Meanwhile,κ-and ι-carrageenan composite sponges possessed good cytocompatability,which had no cytotoxicity to RAW264.7 and NIH-3T3 cells,while λ-carrageenan/agarose composite sponge possessed slight cytotoxicity to NIH-3T3 cells.All the three composite sponges could accelerate the migration of RAW264.7 cells,and could modulate the mRNA expression of cytokines such as TNF-α,IL-6 and IL-10 secreted by the macrophages.The effecting mode of the carrageenan/agarose composite sponges on the mRNA expression of RAW264.7 cells was consistent with the timeline of the skin repair,and would be potential in the application of wound dressing.Among the three types of carrageenan/agarose composite sponge,ι-carrageenan/agarose composite sponge possessed the optimal combination property.