Biosensing Techniques for Mercury Ion Detection

Mercury is a potent neurotoxin that accumulates in aquatic ecosystems and poses severe risks to human health and wildlife. Accurate and rapid detection of mercury ions (Hg²⁺) at trace levels is critical for environmental monitoring, food safety and clinical diagnostics. Biosensing approaches combine biological recognition elements with diverse signal-transduction mechanisms to deliver high specificity, sensitivity and on-site applicability. Core platforms include colourimetric assays, fluorescence sensors, electrochemical interfaces, optical fibre devices and paper-based tests. Many designs exploit the thymine–Hg²⁺–thymine coordination or DNAzyme catalysis, often enhanced by nanomaterials such as gold nanoparticles, metal-oxo clusters or nanoporous metals. Recent efforts aim to minimise instrumentation, shorten response times and extend detection limits into the picomolar range. Integration with smartphones and microfluidics supports user-friendly, low-cost devices for real-time environmental and health surveillance.

Research from Nature Portfolio

Researchers have developed a metal-oxo cluster sensor that undergoes immediate colour change upon Hg²⁺-mediated structural transformation, enabling simple, label-free detection in aqueous samples. A second study introduced a rhodamine 6G-modified nanoporous gold substrate, where metallophilic Hg²⁺–Au⁺ interactions trigger fluorescence quenching, achieving picomolar sensitivity and high selectivity in complex media. A third approach employs a thymine-rich oligonucleotide and intercalating dye; formation of a T–Hg²⁺–T hairpin enhances fluorescence in one step, supporting quantification of environmental water samples down to nanomolar levels.

Biosensing Techniques for Mercury Ion Detection publication trend

The graph below shows the total number of articles in biosensing techniques for mercury ion detection across all publications each year (not limited to Nature Index journals).

Technical terms

DNAzyme: A catalytic DNA sequence that undergoes structural change or cleaves a substrate in the presence of a specific metal ion, employed for selective sensing.

Plasmonic nanoprobe: A metallic nanoparticle, typically gold, whose surface plasmon resonance shifts upon aggregation or binding, producing a visible colour change.

Fluorescence quenching: Reduction of fluorescent emission intensity due to interactions between a fluorophore and a quencher or target analyte.

Thymine–Hg²⁺–thymine coordination: A specific metal–base interaction in DNA where Hg²⁺ bridges two thymine residues, forming a stable complex for selective detection.

Rolling circle amplification (RCA): An isothermal nucleic acid amplification method generating long single-stranded DNA coils to amplify signal in biosensors.

References

1. Low picomolar, instrument-free visual detection of mercury and silver ions using low-cost programmable nanoprobes. Chemical Science (2017).
2. Label-free colorimetric detection of mercury via Hg2+ ions-accelerated structural transformation of nanoscale metal-oxo clusters. Scientific Reports (2015).
3. Selectable Ultrasensitive Detection of Hg2+ with Rhodamine 6G-Modified Nanoporous Gold Optical Sensor. Scientific Reports (2016).
4. A novel label-free fluorescence assay for one-step sensitive detection of Hg2+ in environmental drinking water samples. Scientific Reports (2017).
5. Radial Flow Assay Using Gold Nanoparticles and Rolling Circle Amplification to Detect Mercuric Ions. Nanomaterials (2018).
6. Development of an Aptamer Based Luminescent Optical Fiber Sensor for the Continuous Monitoring of Hg2+ in Aqueous Media. Sensors (2020).