| AVS 56th International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS+NS-WeM |
| Session: | Nanoparticle and Nanoscale Surface Chemistry II |
| Presenter: | S.V.N.T. Kuchibhatla, Pacific Northwest National Laboratory |
| Authors: | S.V.N.T. Kuchibhatla, Pacific Northwest National Laboratory A.S. Karakoti, University of Central Florida C.H. Windisch Jr., Pacific Northwest National Laboratory P. Nachimuthu, Pacific Northwest National Laboratory S. Seal, University of Central Florida S. Thevuthasan, Pacific Northwest National Laboratory D.R. Baer, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Cerium oxide nanoparticles (CNPs) are a subject of increasing attention in the biomedical field in addition to many traditional applications such as catalysis, sensors and fuel cells. Most of the applications of CNPs are driven by the oxygen buffering capability, which in turn is guided by the ability of cerium to switch between 3+ and 4+ oxidation states. The thermodynamic stability of oxygen vacancies in the particles below 10 nm makes this switching more efficient. Motivated by this fact, the CNPs have been used to study their biological response (cell longevity, toxicity and related aspects) and the preliminary results have shown excellent radical scavenging ability. It has also been noted that the CNPs can effectively regenerate the active redox state. However, an unequivocal mechanism is still not reported.
We have studied, in situ, the influence of time (aging) and local environment (chemistry) on the chemistry and structure of CNPs. With the help of UV-Visible and Raman spectroscopy along with microXRD measurements, we have observed that the CNPs are highly dynamic in nature and respond, through changes in chemical state and possibly structure, to the variations in their local environment as a function of time. Raman data with support from XRD and some XPS results suggests that the CNPs undergo the transformation between 3+ and 4+ oxidation state through the formation of a “peroxide-complex” in presence of hydrogen peroxide, which as a function of time leads to the formation of cerium oxide nanoparticles, regeneratively. Interaction of CNPs with hydrogen peroxide was used as a model system for explaining the regenerative nature of CNPs in biological applications. Various results from this study, along with the size dependence of the transitions, will be presented while discussing the merits of the findings and their implications to the bio-medical applications.