Perpustakaan Digital ITB

Nanoceria, typically used for“clean-air”catalyticconverter technologies because of its ability to capture, store, andrelease oxygen, is the same material that has the potential to be usedin nanomedicine. Specifically, nanoceria can be used to controloxygen content in cellular environments; as a“nanozyme”, nanoceriamimics enzymes by acting as an antioxidant agent. The computationaldesign procedures for predicting active materials for catalyticconverters can therefore be used to design active ceria nanozymes.Crucially, the ceria nanomedicine is not a molecule; rather, it is acrystal and exploits its unique crystal properties. Here, we use abinitio and classical computer modeling, together with the experiment,to design structures for nanoceria that maximize its nanozymetic activity. We predict that the optimum nanoparticle shape iseither a (truncated) polyhedral or a nanocube to expose (active) CeO2{100} surfaces. It should also contain oxygen vacanciesand surface hydroxyl species. We also show that the surface structures strongly affect the biological activity of nanoceria.Analogous to catalyst poisoning, phosphorus“poisoning”, the interaction of nanoceria with phosphate, a common bodilyelectrolyte, emanates from phosphate ions binding strongly to CeO2{100} surfaces, inhibiting oxygen capture and release andhence its ability to act as a nanozyme. Conversely, the phosphate interaction with {111} surfaces is weak, and therefore, thesesurfaces protect the nanozyme against poisoning. The atom-level understanding presented here also illuminates catalyticprocesses and poisoning in“clean-air”or fuel-cell technologies because the mechanism underpinning and exploited in eachtechnology, oxygen capture, storage, and release, is identical.