Photoactivatable enzyme upconverting lanthanide nanoparticle conjugates for low energy light driven biocatalysis

Biocatalytic transformations are gaining increasing importance in todays' economy as part of the drive towards more sustainable technology and green chemical synthesis.1 Harnessing solar energy to achieve photo-biocatalysis is even more attractive and several impactful innovations have recently been made in this field. Importantly, light activated chemistry can lead to new chemical pathways and new compounds hitherto unknown in thermal catalysis, opening up new chemical space. In this regard, photo-biocatalysis with UV or visible (blue) light has been developed with photoredox catalyts and light and/or activated enzymes using non-natural electron transfer processes to access new enzyme function. Here, we propose a new alternative to traditional high energy UV-blue light activated enzyme photocatalysis by exploiting more of the solar spectrum and taking advantage of lanthanide upconverting nanoparticles (UCNPs)2 in enzyme-UCNP conjugates (which convert near infra-red light (nIR) to UV or visible light) to enable light activated biocatalysis. At the interface of chemistry, biology, analytical chemistry and physics, this project will involve fabrication of a range of flavoenzymes of the old yellow enzyme family and NADP(H) dependent enzymes that are covalently tethered to UCNPs capable of promoting low energy photo-biocatalysis. Catalytic performance will be assessed and the difference between thermal and photo (UV-visible vs. nIR) activated catalysis in terms of the products produced established. The nature of the excited states and transient radical species will give important mechanistic information and these will be interrogated by a suite of EPR techniques in collaboration with the EPSRC National EPR service in Manchester. Additionally, the possibility of multicomponent and cascade photo-biocatalysis will be investigated using orthogonal chemistries to conjugate different enzymes to the same nanoparticle for example3 as well as the development of in situ bioconjugation strategies.