Overcoming HRP/TMB/H₂O₂ Limitations in LFIAs Using Cerium Oxide Nanozymes with Built-In Peroxidase Activity

Area of Science:

• Nanomaterials Science
• Biotechnology
• Analytical Chemistry

Background:

• Conventional enzyme labels in immunoassays, like horseradish peroxidase (HRP), have limitations.
• Cerium oxide (CeO2) nanozymes, or nanoceria, mimic redox enzymes with tunable Ce3+/Ce4+ redox cycling and oxygen vacancies.
• CeO2 offers advantages over HRP, including stability and reagent-free operation.

Purpose of the Study:

• To review the application of CeO2 nanozymes in lateral flow immunoassays (LFIAs).
• To highlight CeO2's potential for signal amplification and improved sensitivity in diagnostic tests.
• To discuss synthetic control, conjugation, and integration strategies for CeO2 in LFIAs.

Main Methods:

• Review of existing literature on CeO2 nanozymes in various immunoassay formats.
• Analysis of CeO2's catalytic mechanisms (redox cycling, oxygen vacancies).
• Discussion of synthetic methods, antibody conjugation, and LFIA integration.

Main Results:

• CeO2 enables hydrogen-peroxide-free TMB oxidation for strong chromogenic signals with low background.
• CeO2 nanozymes provide stable, reagent-free signal amplification in immunoassays.
• Limited integration of CeO2 into LFIAs reported, indicating a gap in research.

Conclusions:

• CeO2 nanozymes are a promising catalytic label for robust and sensitive LFIAs, suitable for point-of-care testing.
• Challenges include aggregation in high-ionic-strength buffers and synthesis cost.
• Surface functionalization and optimized dispersion can overcome limitations for practical implementation.