Dramatic increase in stability and longevity of enzymes attached to monodispersive iron nanoparticles

Enzymes are proteins that function as biocatalysts in living systems. One of the major concerns in environmental, biomedical, and other applications of enzymes is their short lifetime (J. Kim et al., Single-Enzyme Nanoparticles on Nanostructured Matrices, 2003). Enzymes lose their activity due to oxidation or other processes which results in less stability and a shorter lifetime thereby rendering them less efficient. An effective way to increase the stability, longevity, and reusability of the enzymes is to attach them to magnetic iron nanoparticles. With this aim, two different catabolic enzymes, trypsin and peroxidase, were attached to uniform magnetic core-shell iron nanoparticles (MNPs) produced in our laboratory. Our study indicates that the lifetime of enzymes increases dramatically from a few hours to weeks and that MNP-Enzyme conjugates are more stable, efficient, and economical. We predict that MNPs shield the enzymes preventing them from getting oxidized or self digested. This results in an increased lifetime of the enzymes. Since the magnetization of MNPs is high (similar to 140 emu/g), MNP-enzyme conjugates could efficiently be reused, which makes enzymes more productive. We also found that the enzyme structure plays a major role in efficient attachment of MNPs.