Hydrogels from natural polymers could be very useful for the production of patches, as their physical and chemical properties can be easily tuned by the extent of cross-linking. They also provide a moist environment beneficial for healing. However, until now cross-linking up is associated with the use of toxic chemical linkers, making hydrogels unsuitable for medical applications.

Tzanko Tzanov and colleagues, University Politecnica de Terrassa, Barcelona, Spain, used the enzyme enzyme horseradish peroxidase (HRP) to catalyze the cross-linking of hydrogels from thiolated chitosan in order to avoid harsh chemical cross-linking materials. The team is able to incorporate polyphenolic nanospheres (NSs) from epigallocatechin gallate (EGCG) using this enzyme-mediated gelation. These spheres reinforce the hydrogel structure and are released intact in a sustained manner over 6 days from the hydrogel. EGCG-NSs even show better antibacterial properties than EGCG in solution, but no cytotoxic effect on human cells.

The good biocompatibility of the gel, together with the antibacterial effect of the EGCG-NSs, suggest a promising application in wound management.

• Enzyme-assisted formation of hybrid biopolymer hydrogels incorporating active phenolic nanospheres,
  Petya Petkova, Antonio Francesko, Tzanko Tzanov,
  Eng. Life Sci. 2015.
  DOI: 10.1002/elsc.201400143