Futuristic hydrogen sulfide sensor detecting toxic gas.

Sniffing Out Danger: A Revolutionary Sensor for Hydrogen Sulfide Detection

Reese Marlowe in Tech & Innovation September 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.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.jlumin.2018.11.046, Alternate LINK

Title: Highly Selective Fluorescence Sensor For Hydrogen Sulfide Based On The Cu(Ii)-Dependent Dnazyme

Subject: Condensed Matter Physics

Journal: Journal of Luminescence

Publisher: Elsevier BV

Authors: Guiyin Yue, Da Huang, Fang Luo, Longhua Guo, Bin Qiu, Zhenyu Lin, Guonan Chen

Published: 2019-03-01

Everything You Need To Know

How does the new fluorescence sensor detect hydrogen sulfide (H2S) using Cu(II)-dependent DNAzyme technology?

The fluorescence sensor employs a specially designed DNAzyme, which includes a catalytic strand (Cu-enzyme) and a substrate strand (Cu-substrate). The Cu-enzyme is labeled with a quencher, suppressing fluorescence, while the Cu-substrate is labeled with a fluorescent molecule (FAM) and another quencher. The presence of H2S inhibits the Cu-enzyme from cleaving the Cu-substrate, decreasing fluorescence. This change in fluorescence directly correlates to the concentration of H2S, enabling precise measurement. Without H2S, the Cu(II) ions facilitate the cleavage of the Cu-substrate which then increases fluorescence.

What are the limitations of traditional hydrogen sulfide (H2S) detection methods, and how does this new sensor overcome them using Cu-enzyme and Cu-substrate?

Traditional methods, like lead acetate test papers, suffer from low sensitivity and interference from other gases. Electrochemical methods, while offering higher sensitivity, are susceptible to humidity and oxygen level fluctuations. The new fluorescence sensor, based on Cu(II)-dependent DNAzyme technology, addresses these limitations by providing a simple, selective, and sensitive detection method. The sensor measures H2S concentrations by measuring the fluorescence intensity resulting from the reaction between H2S and Cu(II) ions, using Cu-enzyme and Cu-substrate.

What are the key components of the innovative fluorescence sensor, and how do the Cu-enzyme, Cu-substrate and Cu(II) ions interact to detect H2S?

The sensor's core components are the Cu-enzyme, which is a catalytic DNA strand labeled with a fluorescence quencher, and the Cu-substrate, a DNA substrate strand labeled with a fluorophore and quencher. Cu(II) ions facilitate the cleavage of the Cu-substrate in the absence of H2S which increases fluorescence. The presence of H2S inhibits cleavage decreasing fluorescence. These components work together to produce a quantifiable fluorescence signal that corresponds to the concentration of H2S.

Beyond refuse collection monitoring, what are the broader potential applications of this H2S sensor in environmental monitoring and public safety?

The sensor's potential applications are vast. Its ability to selectively detect H2S makes it invaluable for air quality monitoring, ensuring workplace safety in industries like papermaking and petroleum refining, and protecting public health in areas near garbage stations. The demonstrated accuracy in real-world conditions indicates its reliability for widespread use, possibly leading to advancements in environmental monitoring and occupational safety protocols. Further development could lead to portable devices for on-site H2S detection.

How does the presence of hydrogen sulfide (H2S) affect the function of the Cu(II)-dependent DNAzyme within the fluorescence sensor, and how is this change measured?

The sensor utilizes a Cu(II)-dependent DNAzyme that includes a Cu-enzyme and a Cu-substrate. In the absence of H2S, the Cu(II) ions facilitate the cleavage of the Cu-substrate which increases fluorescence. When H2S is present, it reacts with Cu(II) ions, preventing the Cu-enzyme from cleaving the Cu-substrate. This keeps the fluorescent molecule quenched, and the decrease in fluorescence indicates the H2S concentration. The sensor is able to detect H2S concentrations ranging from 0.5 to 25 µM, with a detection limit of 0.2 µM.