Gold core/ceria shell-based redox active nanozyme mimicking the biological multienzyme complex phenomenon

Area of Science:

• Nanotechnology
• Biochemistry
• Materials Science

Background:

• Individual gold (Au) and cerium oxide (CeO2) nanoparticles exhibit enzyme-like activities (catalase, oxidase, superoxide dismutase, peroxidase).
• Multienzyme complexes in biological systems offer advantages over individual enzymes for metabolic processes.
• Developing a single nanozyme with multienzyme properties has been a long-standing challenge.

Purpose of the Study:

• To design and characterize a functional multienzyme nanozyme using a Gold-Cerium Oxide core-shell nanoparticle (Au/CeO2 CSNP) structure.
• To evaluate the pH-controlled enzyme-like activities (peroxidase, catalase, superoxide dismutase) of the synthesized Au/CeO2 CSNPs.
• To assess the stability, reaction mechanisms, and biosensing potential of the novel core-shell nanozyme.

Main Methods:

• Synthesis of Gold (core)-CeO2 (shell) core-shell nanoparticles (Au/CeO2 CSNPs).
• Characterization of enzyme-like activities (peroxidase, catalase, superoxide dismutase) and kinetic parameters.
• Assessment of stability under extreme pH and temperature conditions; application in glucose detection.

Main Results:

• Au/CeO2 CSNPs demonstrated pH-tunable peroxidase, catalase, and superoxide dismutase activities.
• Peroxidase-like activity was comparable to horseradish peroxidase (HRP), with efficient electron transfer and reduced hydroxyl radical formation.
• The nanozyme exhibited high stability across a wide pH range (2-11) and temperatures (up to 90°C), outperforming natural enzymes.
• Au/CeO2 CSNPs were successfully utilized for glucose detection within a linear range of 100 µM to 1 mM.

Conclusions:

• The developed Au/CeO2 CSNPs function as a robust multienzyme nanozyme with tunable activities.
• The core-shell structure and the redox couple between Au and Ce likely contribute to the enhanced catalytic properties.
• These findings pave the way for developing versatile single-platform nanozyme sensors for diverse biosensing applications.