The Effect Of A Novel Chitosan-Silver Nitrate Gel Dressing On Anti-Septic And Wound Healing

Background and ObjectiveWound infection is the clinical common complications and one of the important factors that result in delayed wound healing.At present,wound infection rate has been significantly reduced by actively wound debridement,reasonable application of antibiotics and nutrition support.,However,the wound infection control is still a problem in clinic since increasing microorganism multiple drug resistance,especially methicillin-resistant Staphylococcus aureus(Methicillin-resistant Staphylococcus aureus,MRSA),in recent decades.Chitosan,also known as acetyl chitin,is obtained by the deacelation function of widespread chitin and has good antibacterial activities via inhibiting growth of some fungi,bacteria,and viruses.Although chitosan has a widespread antibacterial spectrum and is stable on anti-bacterial,even with bacterial drug resistance.However,it's efficacy is low for killing mircobles.In addition,the amino and hydroxyl groups of chitosan could chelated with metal ions(such as,silver ion).According to this feature,we try to combine chitosan with silver nitrate to produce a new material with increasing the effient of killing bactieral and reducing release rate of silver ions.Finally,this new material will keeping the advantages of the chitosan on anti-bacterial and promoting wound healing.Methods1 The synthesis of the novel chitosan-silver nitrate gel dressing and the detection of the released silver ions:Silver nitrate was added into the pure water,stirred to dissolve.Then mixing the silver nitrate with chitosan.Lactic acid was slowly added into the mixture until the chitosan completely dissolved.The new material was placed at room temperature and kept away from light.We put 10g chitosan-silver nitrate gel dressing,pure chitosan and sulfadiazine silver cream into ionic membranes respectively,then put these ionic membtances into beakers which had 1L pure water.And then we took 2 ml water from the beakers respectively to detect the content of silver ions at 1 h,2 h,4 h,8 h,12 h,24 h and 36 h,48 h2 Effects of the new dressing on anti-septic in vitroWe put chitosan-silver nitrate gel dressing,pure chitosan,pure silver nitrate solution,mupirocin ointment and sulfadiazine silver cream 1 ml into12-well culture plate respectively,the control group was PBS.10ul MRSA bacteria liquid drop was added to 0.5 cm x 0.5 cm sterile filter paper,the concentration of MRSA was 1-5 x 10~9 cfu/ml,then each piece of these MRSA papers was put into one kind of drugs.MRSA in these papers were washed 5min later,after that,we took 10ul eluent to coat on the culture medium evenly,counting the bacterial colonies after 24 hours.The same method to test e.coli and candida albicans.3 Effects of the new dressing on anti-septic in vivo:We created 2 cm×2 cm size wounds in rats model,and then 100ul fluorescent MRSA bacteria liquid drop were coated evenly to each wound.Photos were taken with the fusion FX7 pictures taken fluorescent chemiluminescence detector.Rats wounds of three groups were treated with chitosan-silver nitrate gel dressing,mupirocin ointment and sulfadiazine silver cream,binding wounds with gauze bandaging and 3M tape,the control group had no drug processing,we changed fresh dressing for wounds every24 h.4 The impact of chitosan-silver nitrate gel dressing on wound healing in rats:Four groups of rats with wounds were made according to the above mentioned method,Photos of the wounds were taken at d1,d3,d7,d10,and d14 respectively after processing.Deal with rats in the above mentioned method again,and then we took wound materials of rats at d3,d7,and d14 to make HE dyeing observation.Results1 We synthesized new chitosan-silver nitrate gel dressing by chitosan,silver nitrate and gel matrix successfully.Compared with pure silver nitrate,silver ions is slowly released in new materials.The released silver ion amount of new material is less than the amount of sulfadiazine silver cream in same weight.2 Pure chitosan has a good killing effect on gram-positive MRSA and candida albicans,pure silver nitrate have a good inhibition of gram-negative escherichia coli,chitosan-silver nitrate gel dressing with both advantages show almost 100%kill ratio to MRSA,e.coli and candida albicans.3 We can determine the number of MRSA according to fluorescence intensity on wounds.Compared with the traditional drugs,wounds with chitosan-silver nitrate gel dressing do not display fluorescence completely in the first24 h,which means that MRSA had been exterminated entirely.ConclusionChitosan?silver nitrate and gel matrix could easily synthesize a novel chitosan-silver nitrate gel dressing,the new dressing has good sterilization effect and it can promote wound healing.