Aptamer-functionalized 2D photonic crystal hydrogels for sensitive and selective Hg²⁺ detection

Area of Science:

• Materials Science
• Environmental Science
• Analytical Chemistry

Background:

• Heavy metal contamination, particularly mercury (Hg2+), poses significant environmental and health risks.
• Accurate and rapid detection methods for Hg2+ are crucial for water quality monitoring.
• Existing detection techniques may lack sensitivity, selectivity, or on-site applicability.

Purpose of the Study:

• To develop a highly sensitive and selective sensor for detecting mercury ions (Hg2+) in aqueous environments.
• To utilize a two-dimensional photonic crystal hydrogel (2DPCH) functionalized with aptamers for Hg2+ detection.
• To establish a novel, rapid, and on-site detection strategy for heavy metal ions.

Main Methods:

• Fabrication of a two-dimensional photonic crystal hydrogel (2DPCH) sensor.
• Functionalization of the 2DPCH with Hg2+-specific aptamers.
• Detection of Hg2+ based on aptamer-induced hydrogel contraction and changes in photonic crystal structure.
• Quantification of Hg2+ by measuring Debye ring diameter variations using a laser pointer.
• Regeneration and reusability testing of the sensor.

Main Results:

• The sensor achieved a high sensitivity for Hg2+ detection with a limit of detection (LOD) of 0.65 nM over a wide range (1 nM to 1 mM).
• A strong linear correlation (R² = 0.9933) was observed between Hg2+ concentration and sensor response.
• The sensor demonstrated excellent selectivity, reversibility, and stability over multiple uses after regeneration with HCl.
• High recovery rates (94.23%–101.10%) and low relative standard deviations (0.29%–2.55%) were obtained in spiked lake water samples.

Conclusions:

• The aptamer-functionalized 2DPCH sensor provides a robust platform for sensitive and selective Hg2+ detection.
• The sensor's simplicity (laser pointer operation) and reusability make it suitable for on-site, rapid environmental monitoring.
• This approach offers a promising alternative for real-time heavy metal ion analysis in water resources.