Synthesis of Stable Cerium Oxide Nanoparticles Coated with Phosphonic Acid-Based Functional Polymers

Area of Science:

• Nanomaterials Science
• Polymer Chemistry
• Nanomedicine

Background:

• Sub-10 nm metal oxide nanoparticles often lack stability in biofluids when coated with polymers like poly(ethylene glycol) (PEG) via post-synthesis grafting.
• Weak binding affinity of phosphonic acid-terminated polymers leads to detachment, compromising nanoparticle integrity in protein-rich environments.

Purpose of the Study:

• To evaluate functional polymers as coating agents for cerium oxide nanoparticles (CNPs) using a one-step wet-chemical synthesis.
• To enhance the colloidal stability and potential nanomedicine applications of CNPs in biofluids.

Main Methods:

• One-step wet-chemical synthesis introducing PEG-phosphonic acid (PEG-Ph) with cerium precursors.
• Characterization of core-shell CNPs (3 nm cerium oxide core, PEG polymer shell in brush configuration).
• Assessment of colloidal stability in cell culture media and UV-Vis spectroscopy analysis in the presence of hydrogen peroxide.

Main Results:

• Successfully synthesized core-shell CNPs with a high Ce(III) content and functionalized PEG polymer shells.
• CNPs coated with PEG1k-Ph and PEG2k-Ph exhibited significantly increased colloidal stability in cell culture media.
• An additional absorbance band in UV-Vis spectra was observed with hydrogen peroxide, indicating Ce-O2(2-) peroxo-complex formation.

Conclusions:

• One-step wet-chemical synthesis provides a superior method for coating CNPs with functional polymers compared to post-synthesis grafting.
• PEG-Ph coated CNPs demonstrate enhanced colloidal stability, making them promising candidates for nanomedicine applications.
• The observed peroxo-complex formation suggests potential for evaluating the catalytic activity of CNPs in scavenging reactive oxygen species.