Preparation Of Biodegradable Polymer/functionalized Graphene Oxide-based Medical Dressings And Their Properties

In recent years,with the continuous development of biomedical materials,the development of biological macromolecule material which can promote wound healing,antibacterial and good biocompatibility has become the frontier subject of biomedical engineering.Medical dressing is according the actual of the wound,to provide special function for wound healing,it can not only replace the damaged skin as a temporary barrier to avoid or control the wound infection,but also a beneficial environment to wound healing.The research of medical dressing involves the biological,physiological,biochemical,medical,polymer materials and many other expertise of other areas.With the in-depth study of medical dressings,people realize an ideal medical dressing should maintain a moist environment at the wound interface,allow gaseous exchange,act as a barrier to microorganisms and remove excess exudates.But in the clinical study,the bacterial infection of wound is still a very common problem.Therefore,to develop a medical which can promote wound healing,resistant to wound infection and has good biocompatibility is inevitable trend.Since the graphene found that 10 years ago,because of it excellent physical and chemical properties,such as:high electrical conductivity,good thermal stability and excellent mechanical strength,caused a great interest and enthusiasm of researchers.Graphene oxide and reduction graphene oxide have been able to mass production.The promising properties together with the easy of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials.Polyvinyl alcohol(PVA)is a kind of water soluble polymer materials without toxicity and excitant,can be regarded as linear polymer with hydroxyl,it consists of polyvinyl acetate via hydrolysis.A large number of hydroxyl groups on its molecular chain make it has good biological compatibility,due to its biodegradable property,good mechanical properties and the characteristics of easy processing,are widely used in the field of biomaterial,it also has potential application value in the field of drug carrier,biomedical materials and biological membrane separation.In recent years,with the continuous development of medical dressing material,a medical dressing which can promote wound healing,prevent wound infection,have good biocompatibility has become the forefront of biomedical engineering subject and key.In view of this,this topic select the carboxyl graphene oxide(GeneO-COOH)which has a good biocompatibility as matrix material,use L-Tyrosine and L-Arginine which have good biocompatibility,rare earth lanthanum ion(La3+)which has the function of antimicrobial and Polyvinyl alcohol(PVA)which is biodegradable and environmental friendly to collaborative modify the GeneO-COOH,designed and synthesized a series of PVA/Functionalized Graphene oxide nanocomposites.(1)First for graphene oxide(GO)to the cells,especially the human red blood cells and skin fibroblast growth has certain inhibition this defect,we use chloroacetic acid to modify the GO,GeneO-COOH was prepared by the modifying of functional groups,in order to further improve the biocompatibility of GeneO-COOH and promote the ability of cell growth,we control the pH value of the reaction then grafted the L-Tyr onto the slice layer of GeneO-COOH,designed and synthesized a new type of carboxyl graphene oxide-L-tyrosine(GeneO-Tyr)nanocomposites,the experiments show that under the condition of pH=2,GeneO-Tyr-2 is physical adsorbed on the GeneO-COOH,and under the condition of pH=7,10,GeneO-Tyr-7 and GeneO-Tyr-10 is chemically bonded.Static water contact angle test shows that the hydrophily of GeneO-Tyr composites is declined,the contact angle of GeneO-COOH and GeneO-Tyr-2,7,10 is 35.8 °,63.5 °,60.5° and 54.3° respectively,but the compound after modified is still hydrophilic,can provide a wetting environment for wound healing.The cytotoxicity experiment,cell morphological changes test and Hoechst 33342 nuclear staining test results show that the GeneO-Tyr-7 and GeneO-Tyr-10 can promote the NIH3T3 growth.Make it as which has the function of promoting wound healing potential base material of medical dressing material.(2)Although GeneO-Tyr complex compared to GeneO-COOH has better biocompatibility and the ability of promoting cell growth,but don't have function of antibacterial,in order to meet the demand of the function of the new type of medical dressing we use the coordination function of La3+ to GeneO-Tyr and synthesized a novel carboxyl graphene oxide-L-tyrosine-lanthanum(GeneO-Tyr-La)nano composites.Experiments show that La3+ coordinated with oxygen and nitrogen easily,so the La3+ adsorbing on GeneO-Tyr is a kind of chemical adsorption.The cytotoxicity experiment,cell morphological changes test and Hoechst 33342 nuclear staining test results show that the GeneO-Tyr-La can promote the NIH3T3 growth.The antibacterial tests show that the GeneO-Tyr-La compounds have the ability to inhibit the growth of bacteria.Make it as which has the function of promoting wound healing and prevent wound infection potential base material of medical dressing material.(3)In order to further improve the biocompatibility of GeneO-COOH and expectation directly by using modified amino acids to endow them with good antibacterial ability,we choose a particular basic amino acid:L-Arg,using its potential antibacterial ability of side chain guanidine,by controlling the pH value of reaction,grafted L-Arg onto GeneO-COOH slice layer,designed and synthesized a new carboxyl graphene oxide-L-arginine(GeneO-Arg)complex,experiments show that when pH=2,L-Arg esterification reacted with GeneO-COOH,and when pH=7,12,L-Arg amidation reacted with GeneO-COOH.Static water contact angle test shows that the hydrophily of GeneO-Arg composites is declined,the contact angle of GeneO-COOH and GeneO-Arg-2,7,10 is 35.8 °,83.1 °,57.70 and 65.1° respectively,but the compound after modified is still hydrophilic,can provide a wetting environment for wound healing.The cytotoxicity experiment,cell morphological changes test and Hoechst 33342 nuclear staining test results show that the GeneO-Arg-12 can promote the NIH3T3 growth.By the antibacterial test on GeneO-Arg-12,the results show that the GeneO-Arg-12 compounds because of its surface with high positive charge density and the cationic characteristics,easier to interact with the surface of the negatively charged bacteria produce,so as to inhibit the growth of bacteria but the effect is not very significant,need to be further modified.(4)GeneO-Arg compared to GeneO-COOH has better biocompatibility and the ability of promoting cell growth,but no significant antibacterial ability.In order to make the nanocompound with good antibacterial property and excellent biocompatibility.In order to achieve to meet the demand of the function of the new type of medical dressings,we use the coordination function of La3+ to GeneO-Arg and synthesized a novel carboxyl graphene oxide-L-arginine-lanthanum(GeneO-Arg-La)nano composites.Experiments show that La3+ coordinated with oxygen and nitrogen easily,so the La3+ adsorbing on GeneO-Arg is a kind of chemical adsorption.The cytotoxicity experiment,cell morphological changes test and Hoechst 33342 nuclear staining test results show that the GeneO-Arg-La can promote the NIH3T3 growth.The antibacterial tests show that the GeneO-Arg-La compounds have the ability to inhibit the growth of bacteria.Make it as which has the function of promoting wound healing and prevent wound infection potential base material of medical dressing material.(5)0n the basis of the above work,we use PVA,which have good biological physical and chemical properties and GeneO-Tyr,GeneO-Tyr-La,GeneO-Arg,GeneO-Arg-La which synthed fronted through the solution blending reaction,PVA/functionalized graphene oxide composite films have excellent mechanical properties,good antibacterial properties and biocompatibility,which could serve as a kind of medical dressing which can promote wound healing,prevent wound infection.Through SC A test and water absorption test prove that with the joining of GeneO-Tyr,GeneO-Tyr-La,GeneO-Arg,GeneO-Arg-La compounds,PVA/functionalized graphene oxide composite films has stronger ability to absorb wound exudate,provide a wet environment for wound healing.Experiments show that the mechanical properties of PVA/functionalized graphene oxide composite films increased significantly.Cytotoxicity experiment and Hoechst 33342 nuclear staining test showed that PVA/functionalized graphene oxide composite material have no cytotoxicity,and with the addition of GeneO-Tyr,GeneO-Tyr-La,GeneO-Arg,GeneO-Arg-La compounds,PVA/functionalized graphene oxide composite films enhanced the ability of promoting NIH3T3 cell growth.Protein adsorption and platelet adhesion experiments show that PVA/functionalized graphene oxide composite films surface protein adsorption and platelet adhesion ability were improved,which can accelerater the blood coagulation process,promote wound healing.The antibacterial tests show that the PVA/functionalized graphene oxide composite films have the ability to inhibit the growth of bacteria.Make it as which has the function of promoting wound healing and prevent wound infection potential base material of medical dressing material.