Synthesis Of Green Antibacterial Agent Based On Chitosan-antibacterial Peptide Conjugates

In recent years,researchers have paid a great deal of attention on antimicrobial materials like antimicrobial polymers for antimicrobial and disinfection due to drug resistance and multidrug-resistant pathogens increase year by year.Chitosan,a biopolymer of marine origin,has antimicrobial properties and the advantages of being biocompatible,nontoxic,anti-allergy and biodegradable.However,due to inter-and intra-molecular hydrogen bonds,chitosan is mostly dissolved in solvent with p H values below 6.This restrict the applications and biological characteristics under neutral and physiological conditions.In addition,although chitosan has its own antibacterial ability with positive charge,it is far from the requirement of antibacterial materials.Through chemical modification,chitosan was modified with amino acid to form a series of chitosan-amino acid conjugates.The relationship between factors like hydrophilia,hydrophobicity,positive charge strength and antibacterial property was discussed.Three types of N-acetyl amino acids and chitosan reacted with different feeding ratio and reaction time,and the chitosan-amino acid conjugates with different degree of amino substitution of chitosan were prepared.The degree of amino substitution was determined by characterization.In order to further investigate the effects of hydrophilia,hydrophobicity,positive charge strength on antibacterial property,chitosan-amino acid conjugates with different concentration and different degree of amino substitution degree were antibacterially ested.Experimental results showed that the hydrophobic amino acid-modified chitosan were increased antibacterial property to three kinds of bacterial,when the degree of amino substitution was constant and the concentration was increased.At the same concentration,the antibacterial properties of E.coli were increased first and decreased with increase the degree of amino substitution.The antibacterial properties of arginine-modified chitosan was increase with the rising of concentration and degree of amino substitution.But the degree of amino substitution in chitosan-arginine conjugate is only 56%.The MIC of it to S.aureus and E.coli is 1 mg/m L and 2 mg/m L respectively,and the chitosan-arginine conjugate has no antifungal capability on C.albicans.