Small-molecule diagnostics based on functional DNA nanotechnology: a dipstick test for mercury

Area of Science:

• Nanotechnology
• Environmental Science
• Analytical Chemistry

Background:

• Developing sensitive metal ion sensors is crucial for environmental monitoring and human health.
• Mercury (Hg2+) is a toxic environmental pollutant requiring effective detection methods.
• Existing metal ion sensor technologies are not yet fully developed.

Purpose of the Study:

• To develop a novel diagnostic platform for detecting and quantifying mercury ions (Hg2+) in aqueous solutions.
• To create a highly sensitive and selective sensor for Hg2+ using functional DNA-linked gold nanoparticles (AuNPs).
• To establish a practical and rapid detection method for point-of-care diagnostics.

Main Methods:

• Utilized DNA-functionalized gold nanoparticles (AuNPs) as a sensor platform.
• Designed a specific linker DNA molecule to induce AuNP aggregation.
• Leveraged thymine-Hg2+-thymine bonds to trigger linker DNA folding and AuNP disassembly.
• Observed color change from purple to red upon Hg2+ detection.

Main Results:

• Achieved a low limit of detection for Hg2+ at 5.4 nM, below the EPA maximum contaminant level of 10 nM.
• Demonstrated high selectivity for Hg2+ over various other divalent metal ions.
• Observed a rapid and discernible color change indicating the presence of Hg2+.
• Successfully converted the system into a practical dipstick test using lateral-flow devices.

Conclusions:

• Functional DNA-linked AuNPs provide a sensitive, selective, and rapid method for Hg2+ detection.
• The developed sensor is practical for point-of-care diagnostics and environmental monitoring.
• This approach offers a promising advancement in the field of metal ion sensing.