Magnetic bio/nanoreactor with multilayer shells of glucose oxidase and inorganic nanoparticles

Organized multilayers of nanoparticles (9-, 20-, and 45-nm-diameter silica or 12-nm magnetite) and glucose oxidase (GOx) were assembled in alternation with oppositely charged polyelectrolytes on 420-nm latex particles. Stepwise growth of the multilayer films on latex was confirmed by microelectrophoresis and transmission electron microscopy. The inclusion of silica layers on latex yields a higher surface area, resulting in greater GOx adsorption and thereby increasing the catalytic activity of the bioreactor. The bioactivity was proportional to the core surface area and also to the number of GOx layers in the shells. Also, the presence of magnetic nanoparticles allows self-stirring of the nanoreactors with a rotating magnetic field and enhances its productivity. The ensemble of GOx and fluorescent dyes in the shells demonstrated the correlation between Ru-bpy fluorescence and glucose concentration in solution.