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

Abstract 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. Graphical abstract 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.