A paper-based ratiometric sensor for mercury (II) detection using fluorescent carbon dots

Area of Science:

• Environmental Science
• Nanotechnology
• Analytical Chemistry

Background:

• Mercury (Hg²⁺) is a toxic environmental contaminant with significant bioaccumulation.
• Rapid and sensitive detection of Hg²⁺ is crucial for environmental and public health.
• Existing detection methods may lack speed, sensitivity, or portability.

Purpose of the Study:

• To develop a multicolor nanosensor for swift and sensitive detection of Hg²⁺.
• To utilize dual-emissive fluorescent carbon dots (CDs) for ratiometric detection.
• To create a portable device for on-site Hg²⁺ analysis.

Main Methods:

• Synthesized yellow-emissive o-phenylenediamine-synthesized CDs (OPD-CDs) and cyan-emissive m-phenylenediamine-synthesized CDs (MPD-CDs) via solvothermal method.
• Characterized CDs using TEM, XPS, and FT-IR.
• Developed a ratiometric detection method based on fluorescence quenching of OPD-CDs and stable emission of MPD-CDs upon Hg²⁺ exposure.

Main Results:

• The nanosensor exhibited fluorescence quenching of OPD-CDs and stable emission of MPD-CDs in the presence of Hg²⁺, causing a color change from yellow to cyan.
• Achieved excellent selectivity and a low limit of detection (26.8 nM) for Hg²⁺.
• Demonstrated high accuracy in real sample analyses (99.5%-107.5% recovery) and developed a portable paper-based device for on-site detection.

Conclusions:

• The developed dual-emissive fluorescent carbon dot nanosensor provides a rapid, sensitive, and selective method for Hg²⁺ detection.
• The portable paper-based device integrated with smartphone technology enables accurate on-site visual detection of Hg²⁺.
• This technology holds significant potential for environmental monitoring and public health applications.