Researchers at KTH, led by Dr. Natalia Sanz del Olmo, have been developing the antibacterial hydrogel domain of BoneFix and now their work has been published in the Journal of the American Chemical Society. The paper, titled “Antibacterial Hydrogel Adhesives Based on Bifunctional Telechelic Dendritic-Linear-Dendritic Block Copolymers” describes how heterofunctional dendritic-linear-dendritic (DLD) polymers with both cationic charges and alkene groups were used to formulate adhesive and antibacterial hydrogels. The cationic charges allow the hydrogel to disrupt the negatively charged cell wall of the bacteria, while the alkene functional groups allow for the crosslinking of the DLDs together with dithiol crosslinkers into hydrogel networks through high-energy visible (HEV) light induced thiol-ene coupling (TEC) reactions. The use of TEC reactions for constructing the hydrogels allowed the KTH team to change the crosslink density of the hydrogels by simply altering the ratio of the DLD to the dithiol crosslinker, without affecting the number of cationic charges per DLD. Interesting, they found that the activity of the hydrogels against bacteria was impacted by the alkene to thiol ratio. The alkene groups also allowed for the incorporation of other species into the hydrogel through TEC chemistry, such as the cationic molecule cysteamine, which enhanced the activity of the hydrogel towards S. aureus.
In addition to showing activity against both gram positive and negative bacteria, the hydrogels were also highly adhesive to a variety of surfaces, including the hydroxyapatite composite used in the bone fixation patch domain of BoneFix. In the future, the antibacterial hydrogel could be applied on top of the fixation patch and cured to create a top coating, preventing surgical site infections. “Due to the increasing incidence of antimicrobial resistance, the development of new alternatives to conventional antibiotics is crucial” says Dr. Sanz del Olmo. Furthermore, the heterofunctional nature of the DLD, together with the ability to incorporate other biologically interesting molecules is “an interesting feature, which allows for the fine-tuning of the hydrogel properties based on the intended application.”
The paper describing the domain 3 hydrogel can be found at https://pubs.acs.org/doi/full/10.1021/jacs.4c03673. The data used in the paper has been uploaded to an open data repository, which can be found at https://zenodo.org/records/11442132.
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