Preparation,Characterization And Performance Test Of Coptis Chinensis Extract Composites Loaded With Bacterial Cellulose

The slow healing of wounds caused by prolonged blood flow or bacterial infection is one of the factors threatening human health.Therefore,the development of new wound dressings with antibacterial and hemostatic properties is currently a hot research topic.Bacterial cellulose(BC)has excellent mechanical properties,unique three-dimensional network structure,good biocompatibility,strong water retention ability,and is not easy to adhere to wounds.Therefore,it is often used as a carrier for preparing wound dressings;Coptis chinensis extract(CC),as a natural plant extract and traditional Chinese medicine,has antibacterial,anti-inflammatory,healing promoting,antioxidant and other effects.In this study,BC was prepared using independently selected BC synthesis bacteria as a carrier.Different concentrations of coptis extract were loaded into BC by immersion method to prepare bacterial cellulose coptis extract composite materials(BC-CCs).Based on the successful loading verified by SEM and FT-IR,the feasibility of using BC-CCs as wound dressings was further evaluated based on the antibacterial,hemostatic,sustained release,and healing promoting properties of the composite materials.First,three strains of BC producing bacteria were screened from decayed grapes,and their genus was identified as Novacetimonas hansenii by 16 S r RNA amplification sequencing.The strain ZZY-05-31,which uses 1% glycerol as a carbon source and ferments at p H 7.0 and 30 ℃ for 8 days,can produce a membrane with a dry weight of5.48 g/L.The results of SEM and FT-IR showed that the products of the three strains were nano network BC with typical cellulose chemical functional groups.Using BC as a carrier,different concentrations of BC-CCs were prepared by impregnation method:BC-10% CC(BC-CC1),BC-30% CC(BC-CC3),BC-50% CC(BC-CC5),and BC-70%CC(BC-CC7).SEM and FT-IR results showed that irregular block CC was embedded into the pores of BC,and the composite material had both BC and CC characteristic peaks,which verified the successful preparation of the composite material.Secondly,the antibacterial,hemostatic,and sustained-release properties of the composite material BC-CCs were tested.The results showed that the inhibitory effect of BC-CCs on Staphylococcus aureus was better than that of sulfadiazine ointment in the positive control group,and BC-CC5 had the best bacteriostatic effect,with a bacteriostatic rate of 99.89±0.03%.The results of coagulation index(BCI),extracorporeal coagulation time,and rat tail amputation experiments showed that BC-CCs exhibited good procoagulant activity,with BC-CC3 having the best hemostatic effect(BCI value of 46.961%,extracorporeal coagulation time of 3.50 ± 0.38 min,rat tail amputation hemostatic time of 2.50 ± 0.23 min),which was significantly superior to the positive control group gelatin sponge(62.74%,6.62 ± 0.42 min,5.32 ± 0.87 min).The sustained-release performance test results showed that all concentrations of BC-CCs were able to continuously release their drug components within 120 hours.Finally,the healing promoting effect of the material was verified by constructing a mouse trauma model.Test the cytotoxicity of BC-CCs using MTS method,the results showed that BC-CC1 did not exhibit cytotoxicity(cell survival rate was 90.322%),while the cell survival rate after co incubation with BC-CC3 was 42.332%.The cytotoxicity of BC-CCs increased with the increase of CC content in the material.The healing effect of BC-CCs was tested through a mouse wound model healing experiment.The results showed that BC-CCs can effectively promote the healing of mouse wounds,and BC-CC3 showed the best healing effect.The wound healing rate of mice treated with BC-CCs reached 78.34% on the 10 th day.HE staining results showed that BC-CCs had better effects on granulation tissue growth,vascular and hair follicle regeneration,and collagen deposition in mice than in the control group,and effectively avoided inflammatory infiltration;ELISA enzyme linked immunosorbent assay results showed the inflammatory factor IL-1β,IL-6 and TNF-α in the serum of mice treated with BC-CCs Compared with the blank group was significantly downregulated,the mouse transforming growth factor TGF-β1 was significantly upregulated,especially in the BC-CC3 treatment group.In summary,in this study,BC prepared by self screening strains was used as a carrier and CC were impregnated to prepare composite materials with different concentrations.This material has antibacterial,hemostatic,sustained release,and healing promoting properties,and has broad application prospects as a potential medical dressing.