Preparation And Characterization Of Honeysuckle Polysaccharide/Mint Polysaccharide/O-carboxymethyl Chitosan Hydrogel For Wound Dressings

Hydrogel is a new type of biological active dressings which is superior to traditional dressings,and is widely applied in drug release and wound healing.However,there are few active materials used in hydrogels until now,and they often achieve therapeutic effects by loading a variety of drugs.It having been the focus of dressing research that dedicated to finding materials with active effect for medical hydrogel wound dressings.Studies show that the polysaccharides of traditional Chinese medicine have a variety of activities and can be used to prepare active hydrogels for wound dressings.However,the reports focused on polysaccharide hydrogels are seldom.It is found that the polysaccharides from Lonicera japonica has antibacterial activity,and the polysaccharides from Mentha haplocalyx has antiviral and antioxidant activity.The hydrogels prepared by the two polysaccharides may have both antibacterial,antioxidative and antiviral activity and improve their therapeutic effects.Therefore,the hydrogel can reach the requirements of wound dressing.In this experiment,several kinds of hydrogel based on single polysaccharide were prepared and characterized respectively by covalent crosslinking in which the polysaccharides of Lonicera japonica and Mentha haplocalyx are chemical modified and cross-linked with carboxymethyl chitosan,and the composite polysaccharide hydrogel was prepared and characterized on the basis of the above results.The LP and MP were obtained by the methods of water and alcohol and Sevage deproteinized.The polysaccharides were oxidized by sodium periodate,the concentration of aldehyde group increased with increasing the concentration of NaIO₄increasing.So,OLP-2 and OMP-2 with higher aldehyde concentration were selected to prepare oxidized polysaccharide/O-carboxymethyl chitosan hydrogel.After OLP-2 and OMP-2 were cross-linked with carboxymethylated chitosan（O-CCS）bycovalentcross-linking,oxidizedhoneysucklepolysaccharides/O-Carboxymethyl Chitosan Hydrogels（OLPH-1,OLPH-2,OLPH-3）and Oxidized Menthol Polysaccharide/O-Carboxymethyl Chitosan Glue（OMPH-1,OMPH-2,OMPH-3）withdifferent ratios of OLP/OMP to O-CCS（1:1、1:2、1:3）were successfully prepared.Rheological analysis showed that the hydrogel formed by carboxymethyl chitin（O-CCS_b）possess higher mechanical strength,so the polysaccharide hydrogel prepared from O-CCS_b was selected in the experiment.The results of antioxidant test showed that both OLPH,OMPH had certain antioxidant capacity,and the antioxidant capacity of the hydrogel was equivalent or slightly lower than that of oxidized polysaccharides.The SEM image show that all hydrogel samples have porous structures with pore sizes.The gel content of polysaccharide hydrogel increased sequentially,reaching more than 50%.Swelling rates in different media also increased in turn with significantly lower in vitro swelling rates at pH=1.2;at pH=12,the in vitro swelling rate of each hydrogel e increased first and then decreased,and the maximum swelling rate reached 16.58 times of its own mass;At pH=7.4,the in vitro swelling rate of each hydrogel increased slowly.The cumulative release of BSA from each hydrogel in different media decreased in sequence with the ratio of OLP/OMP to O-CCS decreased.Hence,the hydrogel have a sustained release effect on the macromolecular protein and can be used as a drug sustained-release hydrogel dressings.The results of the water evaporation rate showes this polysaccharide hydrogel have a certain degree of water retention and is suitable for wound dressing.Comparing Oxidized Honeysuckle Polysaccharide/O-Carboxymethyl Chitosan Hydrogel（OLPH）and Oxidized Menthol Polysaccharide/O-Carboxymethyl Chitosan Hydrogel（OMPH）,the polysaccharide polysaccharide hydrogel were prepared in a ratio of 3:1（OLP to OMP）in the follow-up experiments.Oxidized honeysuckle polysaccharide/menthol polysaccharide/O-carboxymethyl chitosan hydrogel（OLMPH）was prepared by covalent cross-linking,and its performance was evaluated to study its feasibility in wound dressing.Oxidized Honeysuckle/Menthol polysaccharide/O-Carboxymethyl chitosan hydrogel was successfully prepared by different ratios of oxidative complex polysaccharide（OLMP）to O-CCS（1:1,1:2,1:3）.The morphological analysis shows that OLMPH has a three-dimensional network structure,the OLMPH-3 has smallest pore size and largest pore density for best cross-linking.The FT-IR spectra of OMPH,OLPH,and OLMPH show the characteristic absorption peaks of-C=O and-C-N of amide,which revealed that the covalent cross-linking between oxidized polysaccharide and O-carboxymethyl chitosanThe maximum storage modulus（G’）of the composite polysaccharide hydrogel was 1500 Pa,indicating that the prepared hydrogel had better mechanical strength.The gel content of OLMPH reached more than 70%.At the value of pH in 7.4,the maximum loss rate of the hydrogel reached at 72.37±2.16%in day 21,indicating that the degradation rate of the hydrogel was slow.OLMPH showing strong inhibitory activity against E.coli and Staphylococcus aureus.In the MTT assay,the relative growth rate of the BMSC cells in the OLMPH extract solution was more than 100%,as showed the promoting cell growth effect.Animal experimental results showed that after two weeks,compared with the wound in control group（wound closure area70%）,the closed area of OLMPH-treated wound reached 90%.Furthermore,the presence of OLMPH also enhanced the rate of healing in wounds treated,which was evident from the H&E-stained images.In summary,this research confirmed the oxidized Lonicera japonica polysaccharide/oxidized Mentha haplocalyx polysaccharide/O-carboxymethyl chitosan hydrogel can be prepared by covalent cross-linking.OLMPH can achieve sustained release of biomacromolecules,and possess high swelling rate,strong antibacterial activity,non-toxic and good biocompatibility.In addtion,it promotes wounds to generate regenerated epidermis and accelerates wound healing.Therefore,The oxidized Lonicera japonica polysaccharide/oxidized Mentha haplocalyx polysaccharide/O-carboxymethyl chitosan hydrogel has great potential for wound dressing.