Preparation And Application In Silver Dressing Of Novel Glutathione-Nano Silver Composite Material

Skin is the largest organ on the surface of human b ody,which plays a very important role.It mainly protects internal organs from mechanical damage and bacterial infection.It is a natural protective barrier for human body.However,when damage to the skin occurs in such forms as abrasions,punctures,bur ns,surgical wounds or chronic wounds,the safeguard is destroyed and,in turn,the chance of infection is dramatically increased.Therefore,wound dressi ng is very important to protect the damaged skin from further infection of the external environment.Wound dressing is a kind of materials containing antibacterial agents,and it is developed to cover the wound to prevent wound infection and skin damage.Antibiotics,such as enicillin,are commonly used as antibacterial agents.In the past few decades,antibiotics have saved millions of lives.They have greatly extended human life expectancy,and have been widely used in everywhere.This is not only because of their highly effective bactericidal ability,but also because of their low toxicity to mammalian cells.The discovery of antibiotics is one of the most exciting events in modern medicine.However,the excessive use and abuse of antibiotics ha ve led to the emergence of many drug-resistant bacteria,which have reduced the effectiveness of antibiotics in treating bacterial infections.The mortality,morbidity,and costs associated with long-term treatment have increased significantly,causing greater threat to humans.Therefore,it is an urgent need to develop a new type of antibacterial agents which have significant antibacterial effect and do not easy to produce drug resistance.Silver-based antibacterial materials which can effectively kill bacteria have been used by humans for many years.In recent years,with the rapid development of nanotechnology,nano silver has been widely used in medical treatment and daily life due to its stronger antibacterial activity and less drug resistance.With the widespread use of nano silver,its safety has also received attention.Studies have found that nano silver has a non-negligible toxicity to mammalian cells,which limits its use in clinical medicine.In order to solve the above problems,we prepared a glutathione-nano silver(GSH-AgNPs)composite material with good antibacterial properties and low cytotoxicity,and conducted a series of detailed studies:1.Preparation and characterization of GSH-AgNPs composite materialUsing L-ascorbic acid as the reducing agent and GSH as t he stabilizer,a series of GSH-AgNPs composite materials were synthesized.The particle s ize,morphology,composition,valence state and stability of GSH-AgNPs composite material were studied by UV-vis,TEM,EDS,FT-IR and XPS.2.Study on the antibacterial properties,cytotoxicity and antibacterial mechanism of GSH-AgNPs composite materialsFirst,using different GSH-AgNPs composite materials as antibacterial agents,we studied the effects of the molar ratio of GSH to Ag~+and the concentration of GSH-AgNPs on the antibacterial performance,and the cytotoxicity on mouse fibroblasts.Comparing the above results,a group of materials with the best performance was obtained.Second,using the best-performing group of materials as experimental materials,we studied its antibacterial mechanism against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).Third,we compared its performance with a silver-containing material on the market.The results were showed that the GSH-AgNPs composite material prepared with n(GSH):n(Ag~+)=1:2has the best antibacterial activity,less cytotoxicity and lower cost.Its antibacterial mechanism was divided into two categories:the main antibacterial mechanism for E.coli might be the interaction of nanoparticles with the bacterial cell wall,which results in the change of cell permeability,and ultimately made the bacterial died;while for S.aureus,the main antibacterial mechanism was that the GSH-AgNPs composite material directly entered into the body of bacteria,then it interacted with the internal substances of bacteria which led to the leakage of intracellular substances of bacteria,and eventually made the bacteria died.Comparing the antibacterial and cytotoxicity of GSH-AgNPs composite material with a silver-containing antibacterial material currently on the market,we knew that under the same antibacterial activity,the cytotoxicity of our synthesized GSH-AgNPs composite material was far less than that of silver-containing antibacterial material.The silver antibacterial material met the safety requirements of Class II medical devices,and it was promising to be used as a new type of antibacterial agent with good biocompatibility.3.Application of GSH-AgNPs composite materialFirst,the GSH-AgNPs composite material with the best performance was immersed into the absorbent cotton gauze as an antibacterial agent,and finally we obtained the silver-containing dressing.The morphology,element composition,chemical bond and valence state of silver were studied by FT-IR,SEM,EDS and XPS.Second,using E.coli and S.aureus as experimental bacterias,accord ing to the national standard method,the antibacterial activity of silver-containing gauze was studied.Third,the MTT method was used to study its toxicity against L929 cells.The results showed that the prepared silver-containing dressing was obtained by esterification reactions,and its surface contained a large number of uniform nanoparticles.The antibacterial activity of the silver-containing dressing on E.coli and S.aureus was 100%and 95.45%,respectively,and the cell survival rate was72.32%,which met the national standard.Therefore,it was expected to become a new type of antibacterial dressings.