Colorimetric and Label-Free Optical Detection of Pb²⁺ Ions via Colloidal Gold Nanoparticles

Area of Science:

• Environmental Science
• Nanotechnology
• Analytical Chemistry

Background:

• Lead (Pb) in water poses significant health risks and requires accurate detection methods.
• Current detection methods may lack selectivity or require complex instrumentation.

Purpose of the Study:

• To develop a selective and precise colorimetric method for detecting lead ions (Pb2+) in water.
• To utilize the aggregation of functionalized gold nanoparticles for visual lead detection.

Main Methods:

• Gold nanoparticles (GNPs) functionalized with glutathione (GSH) were synthesized.
• The chelation of Pb2+ by GSH ligands on GNPs was used to induce nanoparticle aggregation.
• Changes in plasmon coupling due to aggregation were monitored via colorimetric shifts.

Main Results:

• The functionalized GNPs selectively detected Pb2+ ions in water.
• Nanoparticle aggregation, triggered by Pb2+, resulted in a concentration-dependent color change (red-to-blue).
• The method enabled instant visual determination of lead content.

Conclusions:

• Glutathione-functionalized gold nanoparticles offer a sensitive platform for colorimetric lead detection.
• This method provides a simple, rapid, and visual approach for assessing lead contamination in water.
• The findings contribute to developing accessible tools for water quality monitoring.