Chip-based scanometric detection of mercuric ion using DNA-functionalized gold nanoparticles

Area of Science:

• Environmental Science
• Nanotechnology
• Analytical Chemistry

Background:

• Mercuric ion (Hg2+) contamination poses significant risks to environmental and human health.
• Accurate and sensitive detection methods for Hg2+ are crucial for environmental monitoring and regulatory compliance.
• Existing detection methods often lack the sensitivity, selectivity, or portability required for widespread application.

Purpose of the Study:

• To develop a novel chip-based scanometric assay for the sensitive and selective detection of mercuric ions (Hg2+).
• To leverage the unique properties of DNA-functionalized gold nanoparticles for enhanced Hg2+ detection.
• To establish the assay's performance in both buffer and environmentally relevant water samples.

Main Methods:

• Utilized DNA-functionalized gold nanoparticles with cooperative binding and catalytic properties.
• Incorporated a thymine-thymine mismatch for selective Hg2+ binding.
• Employed a chip-based scanometric approach for signal detection and readout.
• Validated the assay using buffer and lake water samples, assessing interference from other metal ions.

Main Results:

• Achieved a limit of detection of 10 nM (2 ppb) for Hg2+ in buffer and lake water.
• The detection limit meets the U.S. Environmental Protection Agency (EPA) standard for drinking water.
• Demonstrated high selectivity, distinguishing Hg2+ from 15 other environmentally relevant metal ions.
• The assay showed a 10-fold improvement in sensitivity compared to previous colorimetric methods.

Conclusions:

• The developed chip-based scanometric assay provides a highly sensitive, selective, and rapid method for Hg2+ detection.
• This assay is suitable for environmental monitoring, meeting stringent regulatory limits for mercury in drinking water.
• The method's portability and high throughput make it attractive for point-of-use applications and field testing.