Futuristic hydrogen sulfide sensor detecting toxic gas.

Sniffing Out Danger: A Revolutionary Sensor for Hydrogen Sulfide Detection

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Reese Marlowe in Tech & Innovation April 2025 • 4 min read.

"New fluorescence sensor offers a highly selective and sensitive method for detecting hydrogen sulfide, safeguarding human health and environmental safety."


Hydrogen sulfide (H2S) is a colorless gas known for its pungent, rotten egg odor. It’s a common byproduct of industrial processes like papermaking and petroleum refining, and it also lurks in less obvious places, such as garbage stations. Exposure to H2S, even at low concentrations, can be harmful, causing respiratory, neurological, and cardiovascular issues. Higher concentrations can be fatal, making reliable detection crucial.

Traditional methods for H2S detection, such as lead acetate test papers, have limitations, including low sensitivity and interference from other gases. Electrochemical methods offer higher sensitivity but can be affected by humidity and oxygen levels, making them less reliable in certain environments. The need for a simple, sensitive, and selective detection method has driven researchers to explore innovative solutions.

This pressing need has led to the development of a groundbreaking fluorescence sensor based on Cu(II)-dependent DNAzyme technology. This sensor offers a promising new approach for detecting H2S, with the potential to overcome the limitations of existing methods.

How the Innovative Sensor Works

Futuristic hydrogen sulfide sensor detecting toxic gas.

The core of this sensor lies in a specially designed DNAzyme, a DNA molecule with enzymatic activity. This particular DNAzyme consists of two strands: a catalytic strand (Cu-enzyme) and a substrate strand (Cu-substrate). The Cu-enzyme is labeled with a quencher molecule, which suppresses fluorescence, while the Cu-substrate is labeled with a fluorescent molecule (FAM) and another quencher.

In the absence of H2S, the Cu-enzyme and Cu-substrate hybridize to form a triplex structure, bringing the fluorescent molecule and quenchers into close proximity. This quenches the fluorescence signal, resulting in a low baseline reading. However, when Cu(II) ions are introduced, the Cu-enzyme catalyzes the cleavage of the Cu-substrate, separating the fluorescent molecule from the quenchers and increasing the fluorescence signal.
  • Cu-enzyme: Catalytic DNA strand labeled with a fluorescence quencher.
  • Cu-substrate: DNA substrate strand labeled with a fluorophore and quencher.
  • Cu(II) Ions: Facilitate the cleavage of the Cu-substrate, increasing fluorescence.
  • H2S Presence: Inhibits cleavage, decreasing fluorescence and indicating H2S levels.
The magic happens when H2S is present. H2S reacts with Cu(II) ions, forming CuS, which prevents the Cu-enzyme from cleaving the Cu-substrate. This inhibition keeps the fluorescent molecule quenched, resulting in a decrease in fluorescence intensity. The change in fluorescence is directly related to the concentration of H2S, allowing for accurate quantification. The sensor demonstrates a linear response to H2S concentrations ranging from 0.5 to 25 µM, with a detection limit of 0.2 µM.

Real-World Applications and Future Directions

To demonstrate the practical utility, the sensor was tested on gas samples collected from refuse collectors. The results showed excellent agreement with those obtained using commercial H2S content assay kits, confirming the sensor's accuracy and reliability in real-world conditions. The sensor's ability to selectively detect H2S in complex environments makes it a valuable tool for monitoring air quality, ensuring workplace safety, and protecting public health.

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