Directed enzyme prodrug therapies (DEPT) currently suffer from inherent problems associated with localising and retaining enzymes at tumours. Superparamagnetic iron oxide nanoparticles (SPION) have been synthesised (≈10 nm) and surface functionalised with gold by direct reduction and by attachment of pre-synthesised Au seeds; these Au-SPION sols are stable in aqueous solution and are susceptible to magnetic manipulation. We have genetically modified the nitroreductase (NTR) yfkO from Bacillus Licheniformis to include a sequence of 12 cysteine residues, this modified NTR retains activity with CB1954 and has been immobilised onto gold via the 12 Au-S bonds. The yfkO-cys12 can therefore be immobilised with controlled orientation onto the Au-SPION to allow a magnetically directed enzyme prodrug therapy (MDEPT) to be developed; creating a novel strategy to target and localise prodrug activation to cancer tumour sites using magnetism.