Abstract
Cerium dioxide (CeO2; ceria) nanoparticles (CeNPs) are promising nanozymes that show a variety of biological activity. Effective nanozymes need to retain their activity in the face of surface speciation in biological environments, and characterising surface speciation is therefore critical to understanding and
controlling the therapeutic capabilities of CeNPs. In particular, adsorbed phosphates can impact the enzymatic activity exploited to convert phosphate prodrugs into therapeutics in vivo, and also define the early stages of the phosphate-scavenging processes that lead to the transformation of active CeO2 into inactive CePO4. In this work we utilise ab initio lattice-dynamics calculations to determine the interaction of phosphates with the three major surfaces of ceria and to predict the infrared (IR) and Raman spectral signatures of adsorbed phosphate species. We find that phosphates adsorb strongly to CeO2 surfaces in a range of different stable binding configurations, of which five-fold coordinated P species in a trigonal bipyramidal coordination may represent a stable intermediate in the early stages of phosphate scavenging. We find that the phosphate species show characteristic spectral fingerprints in the 500-1500 cm-1 region, where the bare CeO2 surfaces show no active modes above 600 cm-1
, and the five-fold coordinated P species in particular show potential diagnostic P-O stretching modes between 650-700 cm-1 in both IR and Raman spectra. The comprehensive exploration of different binding modes for phosphates on CeO2 and set of reference spectra provides an important step towards the experimental characterisation of phosphate speciation, and, ultimately, control of its impact on the performance of ceria nanozymes.
controlling the therapeutic capabilities of CeNPs. In particular, adsorbed phosphates can impact the enzymatic activity exploited to convert phosphate prodrugs into therapeutics in vivo, and also define the early stages of the phosphate-scavenging processes that lead to the transformation of active CeO2 into inactive CePO4. In this work we utilise ab initio lattice-dynamics calculations to determine the interaction of phosphates with the three major surfaces of ceria and to predict the infrared (IR) and Raman spectral signatures of adsorbed phosphate species. We find that phosphates adsorb strongly to CeO2 surfaces in a range of different stable binding configurations, of which five-fold coordinated P species in a trigonal bipyramidal coordination may represent a stable intermediate in the early stages of phosphate scavenging. We find that the phosphate species show characteristic spectral fingerprints in the 500-1500 cm-1 region, where the bare CeO2 surfaces show no active modes above 600 cm-1
, and the five-fold coordinated P species in particular show potential diagnostic P-O stretching modes between 650-700 cm-1 in both IR and Raman spectra. The comprehensive exploration of different binding modes for phosphates on CeO2 and set of reference spectra provides an important step towards the experimental characterisation of phosphate speciation, and, ultimately, control of its impact on the performance of ceria nanozymes.
| Original language | English |
|---|---|
| Pages (from-to) | 20183–20193 |
| Journal | The Journal of Physical Chemistry C |
| Volume | 127 |
| Issue number | 40 |
| Early online date | 4 Oct 2023 |
| DOIs | |
| Publication status | Published - 12 Oct 2023 |
Keywords
- cerium oxide
- phosphate electrolyte
- cerium oxide nanoparticles
- InfraRed spectrum
- Raman spectrum
- simulated vibrational spectroscopy
- xide, phosphate electrolyte, cerium oxide nanoparticles, InfraRed spectrum, Raman spectrum, simulated vibrational spectroscopy, d