Analyte-Specific "Signal-On" Uranyl Sensitive Sensing Based on Temperature-Programmed Nanozyme Activity of CoOx

Area of Science:

• Nanomaterials Science
• Analytical Chemistry
• Biochemical Sensing

Background:

• Nanozymes offer advantages over bioenzymes in sensing but lack specificity and catalytic efficiency.
• Existing "turn-off" strategies rely on target-product interactions, limiting sensitivity.
• Developing selective and sensitive nanozyme-based detection methods remains a challenge.

Purpose of the Study:

• To develop a "signal-on" strategy for sensitive and selective uranyl (UO22+) detection using nanozymes.
• To investigate the relationship between oxygen vacancy content, temperature, and catalytic activity of CoOx nanozymes.
• To create a deployable device for on-site uranyl monitoring.

Main Methods:

• Utilized temperature-programming to modulate the peroxidase-mimetic activity of cobalt oxide (CoOx) nanozymes.
• Investigated the direct interaction between uranyl ions and CoOx nanozymes.
• Developed a "light-up" colorimetric assay for uranyl quantification.
• Fabricated a device for intelligent, on-site analyte reading.

Main Results:

• CoOx nanozyme catalytic efficiency showed a positive correlation with surface oxygen vacancy (OV) content, exhibiting a volcano-type trend with temperature.
• Uranyl ions specifically enhanced the peroxidase-like activity of CoOx by increasing OV content.
• The developed colorimetric method achieved a wide detection range (0.01-2 μM) and a low limit of detection (5 nM) for uranyl.
• Demonstrated selective uranyl determination against common interfering species.

Conclusions:

• The proposed "signal-on" strategy enables sensitive and specific uranyl quantification using CoOx nanozymes without bioreceptors.
• The study highlights a facile route for dual modulation of nanozyme activity and analyte response for broader applications.
• The developed method and device facilitate on-site monitoring of uranyl, overcoming limitations of traditional nanozyme sensing.