Poly(ethylene glycol)-based biofunctional hydrogels mediated by peroxidase-catalyzed cross-linking reactions

Biofunctional hydrogels prepared by a peroxidase, especially horseradish peroxidase (HRP), serve as an excellent class of materials or platform for the development of cellular scaffolds because their biocompatibility and mild and tunable reaction conditions provide them with desirable properties. In this focus review, we summarize our decade of research into HRP-mediated fabrication of biofunctional hydrogels and their applications, in particular cell culture scaffolds. A brief overview of potential substrates employed in HRP and improvement of the HRP hydrogelation system from the initial step until the hydrogen peroxide removal stage in an effort to meet environmental standards is discussed. We highlight our system and describe its biocompatibility and ability to functionalize molecules to support biofabrication by increasing cellular adhesiveness, retaining growth factor affinity, and finally accelerating the formation of two- and three-dimensional multicellular architectures. In the last section, we outline the adoption of hydrogelation as a self-standing, compartmentalized reaction system, i.e., the use of hydrogel marble to conduct cell-free biosynthesis. We believe that this HRP-mediated hydrogel system offers great potential not only as a cell culture scaffold but also for various biomedical applications.