Photo-enzymatic dityrosine crosslinking for bioprinting

In this research work, we demonstrate photo-triggering of the horseradish peroxidase (HRP) dityrosine crosslinking. The photo-enzymatic crosslinking of tyramine modified alginate was obtained by introducing riboflavin as a photosensitizer, and by exposing the polymer solution to light radiation at 365 nm. The activation of HRP by light was confirmed by photo-rheology. This crosslinking method proved to be superior to UV crosslinking by riboflavin alone both in terms of kinetics and obtainable storage modulus. Furthermore, activation of HRP by UV light offers the possibility to trigger the onset of the reaction in a precise manner, which is not available with the traditional use of hydrogen peroxide as the activator. The photo-enzymatic crosslinking was applied to bioprinting, to verify its potential in biofabrication techniques requiring precise on-demand crosslinking of hydrogels.