A sensitive photoelectrochemical biosensor based on DepAu/TiO₂ and T-Hg²⁺-T structure

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Environmental Science

Background:

• Mercury ions (Hg²⁺) pose significant environmental and health risks.
• Sensitive and selective detection methods for Hg²⁺ are crucial for environmental monitoring.
• Photoelectrochemical (PEC) biosensors offer promising advantages for ion detection.

Purpose of the Study:

• To design a sensitive photoelectrochemical (PEC) biosensor for mercury ion (Hg²⁺) detection.
• To utilize deposited gold nanoparticles (DepAu) enhanced titanium dioxide (TiO₂) and thymine-Hg²⁺-thymine (T-Hg²⁺-T) structures for signal amplification.
• To achieve sensitive and selective quantification of Hg²⁺ in environmental samples.

Main Methods:

• Fabrication of a TiO₂-modified glassy carbon electrode (GCE).
• Electrochemical deposition of gold nanoparticles (Au NPs) onto the TiO₂/GCE.
• Stepwise modification with T-rich DNA and 1-hexanethiol (HT).
• Detection of Hg²⁺ via photocurrent suppression using the T-Hg²⁺-T complex formation.

Main Results:

• The DepAu/TiO₂/GCE exhibited enhanced photocurrent due to improved photon utilization and charge transfer.
• The T-rich DNA layer and subsequent Hg²⁺ coordination led to significant photocurrent quenching.
• The PEC biosensor demonstrated sensitive and selective Hg²⁺ detection within a wide linear range (100 pmol/L to 100 µmol/L).
• A low detection limit of 33.3 pmol/L for Hg²⁺ was achieved.

Conclusions:

• The developed PEC biosensor provides a highly sensitive and selective platform for Hg²⁺ detection.
• The synergistic effect of Au NPs and the T-Hg²⁺-T structure is effective for signal amplification and detection.
• This biosensing strategy holds potential for detecting other heavy metal ions and environmental contaminants.