Conductive and highly catalytic nanocage for assembly and improving function of enzyme

A conductive nanocage composed of PdNPs-doped (PdNPs = palladium nanoparticles) mesocellular carbon-silica foam was prepared using a designed wet chemical process followed by electrochemical reduction. This nanocage possessed a 3-D interconnected bottleneck mesostructure with large surface area, narrow and controllable pore-size distribution, good biocompatibility, and favorable conductivity and hydrophilicity. The produced PdNPs dispersed homogeneously on the mesowalls and provided the nanocage with a high degree of catalytic ability for the electrooxidation of hydrogen peroxide at an extremely low overpotential, and they offer the possibility to selectively detect oxidase substrates. The nanocage was size-controllable and could be used for volume-selective entrapment of enzymes without aggregation and a change of structure, which preserved good bioactivity of the entrapped enzyme and produced a highly sensitive biosensor with excellent operational and storage stability. Using glucose oxidase as a model, the as-prepared biosensor showed an increase of 130 times in amperometric response due to the presence of PdNPs. The use of the nanocage for enzyme immobilization with excellent catalytic activity of PdNPs will open new horizons for biosensing and biomicroreactor fabrication.