Synthetic Biocatalysis for Unorthodox Applications Seminar

In recent years there has been increasing interest in the application of enzymes for synthetic chemistry. Such biocatalysts promise more sustainable routes towards the synthesis of small organic molecules and are now well established in the production of fine chemical building blocks (e.g. for pharmaceuticals, agrochemicals). There are now efforts to push applied biocatalysis into frontier areas, such as the synthetic manipulation of “inorganic” compounds and materials fabrication. Here, we present two case studies of such work in our laboratory.

In the first case, we report our initial investigations of the silicatein enzymes for the synthetic manipulation of Si-O bonds in a range of organosiloxanes. Here, their catalysis of Si-O bond hydrolysis and condensation was demonstrated with a range of model organosilanols and silyl ethers. Furthermore, we show that silicateins are able to catalyse transetherifications, where the silyl group from one silyl ether may be transferred to a recipient alcohol. Despite close sequence homology to the protease cathepsin L, silicateins appear to exhibit no significant protease or esterase activity when tested against analogous substrates. Overall, these results suggest the silicateins are promising candidates for future elaboration into efficient and selective biocatalysts for organosiloxane chemistry.

In the second case, we exemplify the concept of “biocatalytic nanolithography” through the use of enzyme-functionalised scanning probes for the generation of polymer features on surfaces with nanometre resolution. Specifically, we show that scanning probes bearing recombinantly engineered horseradish peroxidases are able to catalyse the oxidative polymerisation of anilines, to generate polyaniline features in any arbitrary (user-defined) pattern with a resolution of down to 162 nm. This biocatalytic nanolithography could also be applied to parallelised systems using arrays of multiple probes, enabling large area (cm2) patterning while maintaining nanoscale resolution.