A self-assembled amino acid-based hydrogel with broad-spectrum antibacterial activity

Amino acid-based hydrogels with broad-spectrum antibacterial properties are increasingly popular alternatives to existing treatments in the fight against bacterial infection. Here, an amino acid-based hydrogel formed by the self-assembly of N-(9-fluorenylmethoxycarbonyl)-_L-Leucine (Fmoc-L) and Fmoc-_L-Lysine (Fmoc-K) is reported. The Fmoc-L/Fmoc-K hydrogel, which consisted of twisted nanobelts, displayed antibacterial activity against Gram-positive S. aureus, B. subtilis, L. monocytogenes, and Gram-negative E. coli, Sh. sonnei. Specifically, inhibition rates of 97%, 100%, 44%, 45%, and 32% were achieved against S. aureus, B. subtilis, L. monocytogenes, E. coli, and Sh. sonnei after incubation with 4 mM of an Fmoc-L/Fmoc-K hydrogel with the molar ratio of 3:1 for 2 h, respectively. The inhibition rates against E. coli and Sh. sonnei reached 80% and 55% after treatment with 10 mM hydrogel, respectively. The antibacterial activity of hydrogels was time-dependent and enhanced with the prolongation of time. Additionally, the antibacterial activity was easily tailored by modifying the molar ratio of Fmoc-L and Fmoc-K. It was found that Fmoc-L/Fmoc-K hydrogel targeted and destroyed the bacterial cell membrane, causing cytoplasmic leakage and eventually cell death. Moreover, the hydrogel also displayed antibacterial action by inducing the agglomeration of S. aureus. This work demonstrates the potential of amino acid-based hydrogels as a new class of effective antibacterial materials in biomedical applications.

A novel amino acid-based hydrogel formed by the self-assembly of Fmoc-L leucine and Fmoc-L lysine , which consisted of twisted nanobelts, displayed antibacterial activity against Gram-positive and Gram-negative bacteria.