The Closure of the Cycle: Enzymatic Synthesis and Functionalization of Bio-Based Polyesters

The polymer industry is under pressure to mitigate the environmental cost of petrol-based plastics. Biotechnologies contribute to the gradual replacement of petrol-based chemistry and the development of new renewable products, leading to the closure of carbon circle. An array of bio-based building blocks is already available on an industrial scale and is boosting the development of new generations of sustainable and functionally competitive polymers, such as polylactic acid (PLA). Biocatalysts add higher value to bio-based polymers by catalyzing not only their selective modification, but also their synthesis under mild and controlled conditions. The ultimate aim is the introduction of chemical functionalities on the surface of the polymer while retaining its bulk properties, thus enlarging the spectrum of advanced applications.

TrendsDifferent integrated biotechnological advances are gradually replacing petrol-based chemistry and contribute to the development of new chemicals and plastics. Some biobased polymers, such as PLA, are chemically synthesized and are already available on an industrial scale.A long-term contribution to the production of renewable building-blocks and monomers is expected from biotechnology research on the bioconversion of CO2 and microbial electrocatalysis.Advanced applications of polymers are obtainable by introducing chemical functionalities on the surface of the polymer while retaining its bulk properties. Such modifications can change the superficial hydrophobicity as well as introduce a ‘pendant’ as anchoring point or for successively chemical modifications. These possibilities are of key importance, especially for biomedical applications.Biocatalyzed polymerization is not yet economically competitive. The conventional process configurations and reactors used in chemical synthesis do not respond to the complexity of the biocatalytic systems. Thus, the need to improve mass transfer while preserving the integrity of the biocatalyst still requires a specific tailored solution.Robust enzyme immobilization, as well as thin film conditions or ionic liquids, are some of the solutions proposed for overcoming such limitations.