Study On The Impact Of Charge Composition,Distribution And Ion Types On The Antibacterial Properties Of Polypeptide Coatings

The development and application of polymer antibacterial coatings provide a viable solution to address bacterial infections on the surfaces of implantable/interventional medical devices.However,polymer antibacterial coatings generally have only bactericidal or antifouling function,which are prone to dead bacteria adhesion and difficult to achieve long-term antifouling.Therefore,the development of multifunctional polymer antibacterial coatings is of great significance to solve the above-mentioned bacterial infection problems.Polypeptides show promising applications in the field of polymer antibacterial coatings.By simulating the charge composition and amphiphilic structures of natural proteins or peptides,polypeptide coating materials with good antibacterial properties can be obtained.In this paper,we designed and synthesized a series of brush polypeptides with anionic backbone and cationic side chains,as well as linear polypeptides with random distribution of anions and cations,and conducted a systematic study on the specific issue of the composition and distribution of surface charges and ionic types on the influence of antibacterial properties of coatings,including bactericidal,antifouling,antibiofilm properties and biocompatibility.In the first part,the effects of the number of glutamic acid(E)/lysine(K)residues,the length of the main or side chain,the positive/negative charge ratio(P/N)and the charge distribution on the antibacterial properties of polypeptide coatings were focused on.Firstly,for linear polypeptides with random distribution of positive and negative charges,increasing the number of E/K residues and the length of the main chain can improve the antibacterial properties of coatings.Second,for brush polypeptides with negatively charged main chain and positively charged side chains,the positive/negative charge ratio(P/N)plays an important role in the antibacterial performance of coatings,and the brush polypeptide coating with P/N=1 has the best antibacterial performance.The increase in the number of E/K residues is accompanied by an increase in the length of the main chain and/or side chain lc increased,which enhances the antibacterial performance of coatings.Finally,when the P/N=1 and the number of E/K residues were kept constant,the brush polypeptide coating exhibited better antibacterial performance than the linear polypeptide coating.In addition,by adjusting the charge composition and distribution,the coating with optimal antibacterial performance was screened for high bactericidal efficiency,low bacterial adhesion and protein adsorption,low biofilm growth rate and low cytotoxicity,and it had good anti-infection performance in vivo.In the second part,the effect of ion types on the antibacterial performance of brush polypeptide coating was focused on.Based on the first part of the study,the cation group types of brush polypeptide side chains were changed,and polypeptide antibacterial coating with the carboxyl anion main chain and sulfonium cation side chains was prepared.Compared to the brush polypeptide coating with amino cation side chains,the coating with sulfonium cation side chains has a fast bactericidal rate and can completely kill S.aureus within half an hour,and the survival rate of mammalian cells on its surface is enhanced with a high survival rate.In summary,in this paper,brush polypeptides with anionic main chain and cationic side chains and linear polypeptides with random distribution of anions and cations were designed and synthesized.The effects of charge composition,distribution and ion types on the antibacterial properties of polypeptide coatings were clarified,and bactericidal and antifouling integrated multifunctional polypeptide coatings with excellent performance were developed.The structural design of the brush polymers with anionic main chain and cationic side chains provides a certain reference for the development of high-performance antibacterial coating materials.