Fluorescent Probes for Toxic Gas Detection

Fluorescent probes have emerged as powerful tools for the sensitive and selective detection of toxic gases such as nitrogen dioxide, hydrogen sulfide and chlorine. By transducing gas–probe interactions into measurable optical signals, these sensors enable rapid, on-site monitoring under ambient conditions. Recent advances have focused on molecular engineering of the fluorophore and recognition moiety to achieve turn-on, turn-off or ratiometric responses, often exploiting mechanisms such as intramolecular charge transfer, excited-state proton transfer or energy transfer. Nanostructured platforms—including metal–organic frameworks, polymer dots and carbon quantum dots—have further enhanced sensitivity by providing high surface area and tunable microenvironments. Integration with portable devices and test-strip formats has paved the way for real-time, field-deployable assays, underlining the global relevance for industrial safety, environmental monitoring and public health protection.

Research from Nature Portfolio

Recent studies have introduced dual-emission molecular probes that enable ratiometric quantification of nitrogen dioxide with sub-ppb detection limits. These systems harness a pair of covalently linked fluorophores whose relative intensities shift upon irreversible reaction with NO₂, affording self-calibrated measurements that are robust against fluctuations in probe concentration and excitation power.

Another key development involves porous coordination polymers functionalised with organoselenium receptors for hydrogen sulfide sensing. The incorporation of selenium sites facilitates a selective redox reaction with H₂S, triggering fluorogenic cleavage of a quencher and a consequent strong “turn-on” signal. The crystalline host framework imparts rapid kinetics and high reversibility, allowing repeated sensing cycles without loss of performance.

Additionally, supramolecular gel matrices doped with boron–dipyrromethene derivatives have demonstrated highly selective detection of chlorine gas. Exposure to Cl₂ converts the BODIPY core into a non-fluorescent chloride adduct, yielding a sharp fluorescence decay that is visible under UV light and quantifiable by simple photometry. The gel format permits facile fabrication of fibre-optic and wearable sensor patches.

Fluorescent Probes for Toxic Gas Detection publication trend

The graph below shows the total number of articles in fluorescent probes for toxic gas detection across all publications each year (not limited to Nature Index journals).

Technical terms

Fluorescent probe: A molecule or material that emits light upon excitation and undergoes a measurable change in fluorescence in response to an analyte.

Ratiometric sensing: A detection strategy that measures the ratio of two emission intensities, providing built-in calibration against environmental and instrumental variations.

Intramolecular charge transfer (ICT): Electronic redistribution within a molecule upon excitation, often modulated by analyte binding to alter emission wavelength or intensity.

Turn-on/turn-off probe: A sensor whose fluorescence is activated (“turn-on”) or quenched (“turn-off”) in the presence of the target analyte.

Limit of detection (LOD): The lowest concentration of analyte that yields a signal distinguishable from the background noise, typically defined at a specified signal-to-noise ratio.

References

1. The Fluorescent Sensing of BF3 and Amines: A Dual Approach with Hydrazone Ligands. Sensors (2024).