Study On Antibacterial And Anti Bacterial Adhesion Modification Of Elastic Polyurethane Surface

Polyurethane material(PU)plays a very important role in medical materials such as artificial blood vessels and implanted catheters because of its good mechanical properties.However,nonspecific protein adsorption and bacterial adhesion on its surface can lead to secondary bacterial infection after implantation,resulting in adverse reactions and complications.Therefore,in this paper,the surface of the existing PU implant materials was modified with antibacterial and anti-bacterial adhesion,which is mainly divided into three parts,as follows:Firstly,a kind of polyamide macromolecular quaternary ammonium salt(QAS-PAMAM-CYS)containing disulfide bond was synthesized and found to have good antibacterial property.After reducing the disulfide bond,it was fixed on the PU surface containing double bond through the click chemistry of sulfhydryl group and double bond,so as to obtain antibacterial PU film(PU-QAS film),It was found that the film could kill all S.aureus with a concentration of 10~8 CFU ml^-1 within 5 min,and the killing rate of E.coli was 99.9%.Secondly,PU(PU-NCO)with isocyanate end group was synthesized with 4,4-diisocyanate dicyclohexylmethane(HMDI)as condensation agent,1,4-butanediol as hard segment and Pluronic(L-81)as soft segment.Then PU(PU-Allyl)with double bond at both ends was obtained by reacting with hydroxyethyl methacrylate.The triblock copolymer PFGA-b-PU-b-PFGA was obtained by atom degenerate transfer radical polymerization at the end group of Pu-Allyl and chain extension with 2-(perfluorooctyl)ethyl methacrylate(FMA)and glycidyl methacrylate(GMA)as monomers.The side chain epoxy group of the polymer reacts with cystine dihydrochloride and cuts off the disulfide bond to obtain a triblock copolymer PFGA-b-PU-b-PFGA-SH containing sulfhydryl group.It is coated on the surface of PU material with similar structure to PU in the middle of the polymer as a surface modifier,and then Ag NP is fixed on the surface through the interaction between sulfhydryl group and silver,so as to obtain PU film with surface biological inertia and antibacterial properties,named PU-PFGA-Ag film,The maximum contact angle of its surface can reach 141°.The film was coated on the inner and outer surfaces of PU catheter to form an antibacterial and anti adhesion coating.Dynamic antibacterial and anti bacterial adhesion tests showed that there was still no large amount of bacterial adhesion on the catheter surface after 36 h,and a small amount of residual bacteria could also be killed by silver ions.Finally,the dendritic quaternary ammonium salt PPQN containing perylene was synthesized and fixed on the surface of porous graphene oxide electrode by?-?conjugation.A PPQN-electrode sensitive to bacteria was obtained.Using this electrode to detect the content of bacteria(S.aureus and E.coli)in water,it was found that the detectable bacterial concentration was as low as 2 CFU ml^-1.