Nanocomposites and Nanomaterials

Construction and characterization of polymer-coated CeO2
Hubina A.V.1, Lobko Ye. V.2, Tarasyuk O.P.1, Rogalsky S.P.1
 1 V.P.Kukhar Institute of Bioorganic Chemistry and Petrochemistry NAS of Ukraine, Kharkivske shose, 50, Kyiv-02160, Ukraine. 
E-mail: zurako@ukr.net
2 Charles University, V Holešovičkách 747/2, 18000 Praha 8, Czech Republic

CeO2 nanoparticles (CeNP) exhibit outstanding antioxidant activity due to redox change between Ce3+ and Ce4+ in response to the conditions of the media. These properties allow nanoceria to demonstrate properties similar to such enzimes as superoxide dismutase, peroxidase, oxidase etc. The use of CeNP as enzyme-mimetic agents in biomedicine meets difficulties due to self-aggregation of NP and low stability of the suspension. 
In this research we constructed polymer-coated CeNP with enhanced stability which demonstrate high level of antioxidant activity. The series of polymers .including poly (acrylamide) (pAA), and poly (methacrylic acid) (pMA) were synthesised by means of controlled radical polymerization (CRP). pAA was synthesized  via nitroxide-mediated polymerization while pMA was obtained using CRP in the presence of metal complexes. 
The polymers obtained by both CRP methods showed narrow polydispersity in the range of 1,2- 1,4 according to GPC data. Hybrid polymer-CeO2 nanoparticles were obtained via nanoprecipitation method. TGA results demonstrated that the ratio of inorganic and polymer was app. 75:25. 
Antioxydant activity of polymer-coated CeNPs was determined using TMB assay (peroxidase activity) and SOD assay (superoxidase dismutase). Obtained results revealed that polymer-coating did not affect the peroxidase-mimic activity of CeNP but noticeably enhanced the superoxidase dismutase-like properties of nanoceria.