Issue 27, 2021

Antimicrobial and degradable triazolinedione (TAD) crosslinked polypeptide hydrogels

Abstract

Hydrogels are perfectly suited to support cell and tissue growth in advanced tissue engineering applications as well as classical wound treatment scenarios. Ideal hydrogel materials for these applications should be easy to produce, biocompatible, resorbable and antimicrobial. Here we report the fabrication of degradable covalent antimicrobial lysine and tryptophan containing copolypeptide hydrogels, whereby the hydrogel properties can be independently modulated by the copolypeptide monomer ratio and chiral composition. Well-defined statistical copolypeptides comprising different overall molecular weights as well as ratios of L- and D-lysine and tryptophan at ratios of 35 : 15, 70 : 30 and 80 : 20 were obtained by N-carboxyanhydride (NCA) polymerisation and subsequently crosslinked by the selective reaction of bifunctional triazolinedione (TAD) with tryptophan. Real-time rheology was used to monitor the crosslinking reaction recording the fastest increase and overall modulus for copolypeptides with the higher tryptophan ratio. Water uptake of cylindrical hydrogel samples was dependent on crosslinking ratio but found independent of chiral composition, while enzymatic degradation proceeded significantly faster for samples containing more L-amino acids. Antimicrobial activity on a range of hydrogels containing different polypeptide chain lengths, lysine/tryptophan composition and L/D enantiomers was tested against reference laboratory strains of Gram-negative Escherichia coli (E. coli; ATCC25922) and Gram-positive, Staphylococcus aureus (S. aureus; ATCC25923). log reductions of 2.8–3.4 were recorded for the most potent hydrogels. In vitro leachable cytotoxicity tests confirmed non-cytotoxicity as per ISO guidelines.

Graphical abstract: Antimicrobial and degradable triazolinedione (TAD) crosslinked polypeptide hydrogels

Supplementary files

Article information

Article type
Paper
Submitted
08 Apr. 2021
Accepted
22 Maijs 2021
First published
24 Maijs 2021

J. Mater. Chem. B, 2021,9, 5456-5464

Antimicrobial and degradable triazolinedione (TAD) crosslinked polypeptide hydrogels

S. D. Kimmins, S. B. Hanay, R. Murphy, J. O’Dwyer, J. Ramalho, E. J. Ryan, C. J. Kearney, F. J. O'Brien, S. Cryan, D. Fitzgerald-Hughes and A. Heise, J. Mater. Chem. B, 2021, 9, 5456 DOI: 10.1039/D1TB00776A

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