Characterization and antibacterial mechanism of poly(aminoethyl) modified chitin synthesized via a facile one-step pathway

This work aims to synthesize poly(aminoethyl) modified chitin (PAEMC) and ascertain its antibacterial activity and mechanism. FTIR and ¹H NMR results proved aminoethyl moieties were grafted to C6OH and C3OH on chitin backbone in the form of polymerization. XRD and TG/DTG analyses manifested its well-defined crystallinity and thermostability. PAEMC, with average molecular weight (MW) of 851.0 kDa, degree of deacetylation (DD) of 27.95%, and degree of substitution (DS) of 1.77, had good solubility in aqueous solutions over the pH range of 3-12, and also possessed high antimicrobial activity against Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus proteus, and Klebsiella pneumoniae, commonly causing chronic wound infections. Nucleic acid release, protein leakage, increased inner membrane permeability, and decreased cell surface hydrophobicity implied bacterial cytomembranes were substantially compromised in the presence of PAEMC. Microscopically, PAEMC visually perturbed bacteria, illustrating deformed and even collapsed morphologies. Overall, PAEMC possessed good solubility, effectively destroyed bacteria via a membrane damage mechanism, and might serve as an antibacterial agent for treatments of chronic wound infections.