About the Project

An estimated 31.9 million tonnes of mismanaged plastic waste enters the environment annually,[1] contaminating oceans and terrestrial ecosystems. This poses a severe threat to the environment and wildlife, and also results in the loss of a valuable carbon source. While some plastics can be mechanically recycled, this rapidly diminishes the material properties until the recyclate is no longer useful. Chemical recycling to monomer is therefore emerging as an important complementary technique, where the monomer can be re-polymerised into materials with properties comparable to virgin plastics.

The use of biotechnology solutions to depolymerise plastic waste is a growing area of interest, with lipases, cutinases and PETases reported for poly(ethylene terephthalate) (PET) depolymerisation.[2] While most enzymes can only depolymerise amorphous PET, exciting recent advances suggest that enzymes can depolymerise crystalline PET under certain conditions.[3] This is a key finding, as incomplete depolymerisation can generate damaging microplastics. In contrast, most metal-based catalysts can depolymerise both amorphous and crystalline regions of PET, yet generally use harsh reaction conditions. Due to stability issues, this limits the use of ligands designed to enhance catalyst activity, although recent studies have shown that heterobimetallic catalysts can effectively depolymerise polyesters.[4]

This collaborative project harnesses the power of both enzymes and metal-based catalysts, by incorporating metal-salen complexes into artificial metalloenzymes designed to stabilise the metal-salen and direct the polymer towards the active site. The catalysts will be explored for polyester depolymerisation, specifically investigating poly(lactic acid) (PLA) and poly(ethylene furanoate) (PEF). These two materials are emerging as next-generation green polyesters; both are bio-based, non-toxic, and generate lower CO₂ emissions than some conventional plastics.[5] Several studies, including our own research, have shown that salen complexes can be successfully incorporated into artificial metalloenzymes to deliver enhanced catalyst performance, yet the use of artificial metalloenzymes remains underexplored in depolymerisation.[6] The catalysts will be optimised by modulating the salen structure, including the use of chiral salens for depolymerising PLA of different tacticity.

This project would suit a student interested in sustainability and interdisciplinary research, and training will be provided in molecular biology, synthetic chemistry and analysis.

Application deadline: 16 November, 2026

For more information and to apply visit https://www.findaphd.com/phds/project/eastbio-partnership-polyester-depolymerisation-mediated-by-artificial-metalloenzymes/?p199782