Design, synthesis and evaluation of antibacterial activity of peptide polymer based on branched PEI as a biomimetic polymer

Biomimetic means imitating models, systems, and elements of nature to solve complex human problems. This field of science has led to the creation of new technologies inspired by biological solutions in macro and nano sizes. Thousands of people die every year due to diseases caused by antibiotic resistance. Therefore, the use of antimicrobial peptides has become particularly important.

in this study, branched polyethyleneimine polymer has been used as a biomimetic polymer of antibacterial peptides. In order to increase the antibacterial properties, the amino acids valine and lysine were used to modify the surface of branched polyethyleneimine. 1 H-NMR and FTIR were used to prove the binding of amino acids to the polymer. Antibacterial activity of the modified polymer by two methods of MIC test and growth inhibition zone on gram-positive bacteria S. aureus and B. subtilis and gram-negative bacteria E. coli and P. aeruginosa were examined.

Under optimal conditions, the concentration of branched polyethyleneimine polymer was 8 μl, and the amino acid valine to lysine ratio was 1: 6. Polyethyleneimine polymer modified with the amino acids valine and lysine inhibited bacterial growth concentration-dependent (p <0.05). 5 mg/ml of this polymer inhibits the growth of bacteria by more than 70%. The diameter of the inhibition zone of this polymer in examined bacteria reached about 15-20 mm. The antibacterial activity of this polymer was comparable to that of the antibiotic cefepime. It seems that this polymer can be used as an antibacterial polymer.