AVS 57th International Symposium & Exhibition
    Nanometer-scale Science and Technology Monday Sessions
       Session NS-MoA

Paper NS-MoA10
Functionalized Ceria Nanoparticles – Influence of Coating Thickness and Density on Their Reactivity

Monday, October 18, 2010, 5:00 pm, Room La Cienega

Session: Nanomaterials in the Environment
Presenter: A. Karakoti, University of Central Florida
Authors: A. Karakoti, University of Central Florida
S. Kuchibhatla, Pacific Northwest National Laboratory
G. Orr, Pacific Northwest National Laboratory
H. Wang, Pacific Northwest National Laboratory
D.R. Baer, Pacific Northwest National Laboratory
S. Seal, University of Central Florida
S. Thevuthasan, Pacific Northwest National Laboratory
Correspondent: Click to Email

Topical interest in the biomedical applications of cerium oxide nanoparticles (CNPs) has emerged from its radical scavenging, antioxidant like, behavior. The ability of CNPs to carry these single electron redox processes (radical scavenging) stems from the ability of cerium to switch between the Ce3+ and Ce4+ oxidation states. It is essential to test and increase the biocompatibility and solubility of CNPs to be able to use these in biomedical applications as it involves a direct interface of nanoparticles with the intracellular environment. The biocompatibility as well as solubility of CNPs can be increased by modifying the surface with biocompatible polymers as ligands. Such a composite system should be able to demonstrate the unaltered characteristics of the parent CNPs and biocompatibility as well as high solubility of the polymeric system. Thorough characterization of CNP-polymer system such as thickness of polymeric coating, surface coverage and number density of the polymer per nanoparticle is necessary to relate its properties with biocompatibility.

CNPs were synthesized using two different wet chemical methods and coated with different concentration of polymer (polyacrylic acid) using conventional precipitation and redispersion technique. The molecular weight of the polymer was varied between 2,000 and 250,000 g/mol and composite system was characterized for particle size, stability/solubility of dispersion, surface charge, surface density of the polymer and thickness of the polymeric coating. Dynamic light scattering measurements were used to characterize the size as well as surface charge of the coated nanoparticles. A combination of surface area and thermogravimetric analysis was used to ascertain the number density of the polymers per unit surface area of the nanoparticles. The extent of polymeric functionalization will be determined by estimating the number of carboxyl groups on the surface of nanoparticles by chemical probing. Non linear optical (NLO) measurements are becoming increasingly popular to quantify the surface of nanoparticles. NLO analyses such as Sum Frequency Generation Vibrational Spectroscopy (SFG-VS) will be used to quantitatively estimate the polymeric ligands on the surface of CNPs. The presentation will be concluded by some of the preliminary results from the biocompatibility tests carried out on the well analyzed composite/functional CNPs.