LSPR-Driven Dual-Mode Urea Sensor for Milk Adulteration Detection Using Gold Nanobipyramids and Upconversion...

Area of Science:

• Analytical Chemistry
• Materials Science
• Biotechnology

Background:

• Food quality and safety are paramount to public health, with milk adulteration posing significant risks.
• Urea adulteration in milk is a prevalent issue, necessitating sensitive detection methods.

Purpose of the Study:

• To develop a highly sensitive dual-mode (colorimetric and fluorometric) sensor for detecting urea in milk.
• To utilize enzymatic hydrolysis and plasmonic etching for accurate urea quantification.

Main Methods:

• Employing urease-catalyzed hydrolysis of urea to produce ammonia, which modulates Fenton reactions and localized surface plasmon resonance (LSPR) of gold nanobipyramids (AuNBPs).
• Utilizing Förster resonance energy transfer (FRET) between AuNBPs and upconversion nanoparticles (UCNPs) for ratiometric fluorometric sensing.
• Integrating a smartphone-based RGB analysis for accessible on-site monitoring.

Main Results:

• Achieved a broad detection range (0-5 mM) for urea with a low limit of detection (LoD) of 0.09 μM in colorimetric mode.
• Demonstrated high sensitivity in fluorometric mode with an LoD of 0.056 μM, featuring a dynamic "Off/On-On/Off" response.
• Validated the sensor's potential for real-world applications through smartphone integration.

Conclusions:

• The developed dual-mode sensor offers a sensitive and accessible platform for detecting urea adulteration in milk.
• This technology holds promise for improving food safety and public health through rapid, on-site analysis.