The Preparation Of Antimicrobial Peptides Surface And Its Stability Improvement

Implant devices are widely used in clinic,but bacterial infections are common challenges in the application.Surface modification is one of effective methods to improve the antibacterial property of implant devices.Antibacterial peptides,a kind of small molecular peptide with antimicrobial activity,are typically 9–50 residues with a wide range of sequence diversity mainly consisting of cationic and hydrophobic residues,and show broad-spectrum efficient antimicrobial properties and not easy to result in drug-resistance.However,when being applied in vivo,the bottleneck of the antimicrobial peptide often lies on the stable activity.To solve this problem,incorporating poly(zwitterion)and antimicrobial peptide on surface via SI-ATRP and "click" chemistry is applied here.Modifying the N-terminal of the peptide is one of the ways to improve the effectiveness of antimicrobial peptides.We chose pepetide HHC36 for our study,and modified it at Nterminal with L-propargylglycine to get a salt-tolerant and alkyne–terminated peptide(Pra HHC36).Results show that both HHC36(AMP)and Pra HHC36(Pra AMP)had wonderful antimicrobial effect to E.coli and S.aureus,MIC100 of AMP was 6 ?M and 8 ?M,and Pra AMP was 8 ?M and 10 ?M,but had better salt-tolerant property and remain good antibacterial effects in PBS.They both showed cytotoxicity to m BMSC.Incorporating poly(zwitterionic)and antimicrobial peptide via SI-ATRP and "click" reaction to immobilize AMP onto surface,in order to improve AMP's stability to enzymolysis.Biotin-avidin system test shows that the feasibility of the combination of ATRP and click chemistry on surface;XPS results of wafers grafting polySBMA and Pra AMP,show that the C 1s and N 1s narrow spectrum of surface containing amido bond in pepetides,and N+ in SBMA,demonstrate that polySBMA and Pra AMP are successfully grafted on the model surface.Water contact Angle,AFM also provides relevant auxiliary results.Antimicrobial property of control and experiment group were up to 99%,moreover,the group incorporated polySBMA show much better enzymolysis tolerance.In the meantime,surface immobilized with peptide Pra AMP showed no cytoto-xicity to mBMSC.Membrane disruption mechanisms of antimicrobial peptide was also explored here.Nucleic acid leakage showed that the membrane of bacteria was destroyed by antibacterial peptides,and lead to the death of bacteria.We can observe visually holes on the cell membrane and the loss of bacterial content from the images of TEM and SEM.Fluorescent leakage experiments indicated that the hole size on membrane of bacteria destroyed by peptide was over 9 nm.