Preparation And Antibacterial Properties Of PH Responsive Fluorinated Copolymer

The occurrence of many diseases is closely related to the colonization and proliferation of pathogenic microorganisms,especially the infection of biomedical equipment caused by bacteria is one of the common complications in hospitals.It not only affects people's production and life,but also seriously threatens human health.Therefore,the prevention of bacterial infection on the surface of biomedical materials has aroused widespread concern.At present,many materials that can effectively inhibit the growth of bacteria have been developed,such as many cationic antibacterial materials including quaternary ammonium salts,antibiotics,silver,antimicrobial peptides and so on.However,there are few antibacterial materials that can detect bacterial infections.Due to the mild symptoms in the initial stage of infection and the lack of effective means to monitor the infection site,it is easy to miss the best time for treatment,which leads to the further aggravation of infection.This is a big challenge for the safety and reliability of biomedical equipment that needs to be used for a long time.As is known to all,the microenvironment of bacteria is weakly acidic in the process of growth and proliferation.Therefore,according to this characteristic,We synthesized five fluorinated copolymers in different proportions through RAFT polymerization.Then,the pH-responsive fluorescent molecule spiropyran was grafted onto the copolymer by esterification reaction.Finally,the copolymer compound was obtained by compounding the bactericide by the method of electrostatic interaction.The composite antibacterial coatings with anti-adhesion,sterilization and pH-response were prepared simply and efficiently by dropping.The details are as follows:1.Preparation and characterization of pH responsive fluorinated copolymer:The pH responsive spiropyran and reversible addition fragmentation chain transfer(RAFT)reagent(DDMAT)were synthesized firstly.Then methacrylic acid(MAA)and 1H,1H,2H,2H-perfluorodecyl ethyl acrylate(FDA)were synthesized by RAFT polymerization.The pH responsive copolymers P(MAA-co-SP-co-FDA)were prepared by changing the molar ratio of MAA / FDA and adjusting the mole fraction of the two in the molecular chain of the copolymer.Then the carboxyl group in the copolymers P(MAA-co-FDA)were esterified with the hydroxyl group on spiropyran(SP)molecule to obtain the pH responsive copolymers P(MAA-co-SP-co-FDA).The complexs of P(MAA-co-SP-co-FDA)/PHMB were prepared by complexation of the carboxyl group of P(MAA-co-SP-co-FDA)/PHMB with protonated polyhexamethylene biguanide(PHMB).FTIR,NMR,XPS and other characterization proved the successful synthesis.2.Characterization of the properties of the copolymer composite coating:The coatings were constructed on the surface of silicon wafer by drop coating.Firstly,the anti-bacterial adhesion experiments were carried out on the copolymer coating with different fluorine content,and the copolymer with the best anti-bacterial adhesion performance was selected.On this basis,the antibacterial,fluorescence imaging and biocompatibility were characterized.The bacteriostatic zone test showed that the coating kill bacteria by releasing PHMB and the bacteriostatic rate of Staphylococcus aureus and Escherichia coli can reach 99.9 %.Fluorescence spectra,UV-vis spectra and confocal imaging experiments showed that the complex has good pH response and can be applied to the imaging of bacterial microenvironment.Biocompatibility experiments showed that the viability of 3T3 embryonic fibroblasts is as high as 93 % and has a low hemolysis rate,so it is suitable for a variety of medical devices to reduce bacterial infection in vivo and in vitro.This study provides a simple construction strategy for the preparation of antibacterial coating materials with excellent antibacterial,antifouling and pH response properties,and has a broad application prospect in the fields of antibacterial,antifouling and bacterial monitoring of antibacterial medical devices.