ATRPases: Enzyme catalysts for Atom Transfer Radical Polymerization

Controlled living radical polymerizations have recently received significant attention in polymer science, as they enable the production of well-defined functional polymers with complex architectures and predetermined molecular weights, as well as narrow molecular weight distributions. Atom transfer radical polymerization (ATRP) has become one of the most widely used polymerization techniques due to its versatility: it can be applied using the majority of common monomers, it allows the addition of functional groups and it is compatible with numerous biomolecules. However, the transition metal catalysts required for ATRP can represent a challenge, as they can be toxic and potentially harmful to the environment. Moreover, the catalysts can have a negative impact on the polymer properties if not fully removed from the product.

A “greener” approach involves the use of enzymes as catalysts, so-called “ATRPases”, rather than transition metals. We have discovered that metalloproteins such as horseradish peroxidase (HRP) and hemoglobin catalyze ATRP of numerous monomers in aqueous solutions. As enzymes are non-toxic, derived from renewable resources and easy to remove from a polymer solution, biocatalytic ATRP offers a new route for the environmentally benign synthesis of metal-free polymers. Current work in our group aims to elucidate the fundamental chemical and biochemical aspects of the enzyme-catalysed ATRP. Furthermore, we work on optimizing the performance of these biocatalytic ATRPases and on expanding the scope of monomers and reaction conditions under which they function.

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