Fluorescent Sensing of Zinc Ions in Biological Systems

Zinc ions play indispensable roles in enzymatic catalysis, gene expression and cellular signalling, yet their labile pools are tightly regulated and often confined to specific subcellular compartments. Fluorescent sensing has emerged as a powerful approach to visualise Zn2+ dynamics in living cells and tissues in real time, offering high spatial resolution and minimal perturbation. At the heart of these methods lie small-molecule or protein-based probes that combine a zinc-selective chelating unit with a chromophore whose emission responds to metal binding. Mechanisms such as photoinduced electron transfer and intramolecular charge transfer are exploited to deliver turn-on or ratiometric signals, enabling quantitative mapping of zinc distribution. Advances in probe design have targeted enhancements in brightness, selectivity over competing metal ions, water solubility and organelle targeting. Meanwhile, imaging modalities ranging from confocal and two-photon excitation to super-resolution structured illumination microscopy have extended detection sensitivity from individual cells to three-dimensional organoids and live brain slices. These tools are now central to studies of zinc-dependent processes in neurobiology, immunology and developmental biology, and hold promise for diagnostic and therapeutic applications in disorders of zinc homeostasis.

Research from Nature Portfolio

Recent studies have introduced a single-probe strategy for simultaneous tracking of labile Zn2+ in multiple organelles by combining a turn-on fluorescent sensor with structured illumination microscopy. By fine-tuning the lipophilicity of a naphthalimide-based probe, research teams achieved selective accumulation in mitochondria, endoplasmic reticulum and vesicular compartments while excluding the nucleus, and demonstrated its use to visualise mitophagy-associated zinc transients in HeLa cells and to image zinc dynamics in stem-cell-derived organoids. In parallel, a bespoke bispyrrole ratiometric probe has been deployed to record real-time zinc fluxes in hippocampal slices under epileptic challenge. This sensor exhibits a green-to-red emission shift upon zinc binding, enabling quantification of synaptic zinc translocation in vitro and in vivo, and thereby providing new insights into zinc’s role in neuronal signalling and seizure pathology.

Fluorescent Sensing of Zinc Ions in Biological Systems publication trend

The graph below shows the total number of articles in fluorescent sensing of zinc ions in biological systems across all publications each year (not limited to Nature Index journals).

Technical terms

Fluorescent probe: A molecule that emits visible light upon excitation and changes its emission properties upon binding a specific analyte, enabling visualisation in biological environments.

Two-photon excitation: A microscopy technique that uses simultaneous absorption of two infrared photons to excite a fluorophore, allowing deeper tissue penetration and reduced photodamage.

Turn-on fluorescence: A sensing mechanism in which fluorescence is initially quenched and is restored upon analyte binding, producing a strong contrast.

Ratiometric sensing: A method that measures the ratio of two emission wavelengths from a single probe, providing quantitative values that are less sensitive to probe concentration and environmental factors.

Structured illumination microscopy (SIM): A super-resolution imaging technique that uses patterned light to improve spatial resolution beyond the diffraction limit.

Chelator: A chemical moiety with donor atoms that selectively binds metal ions, forming stable complexes and conferring specificity to a sensor.

Organelle targeting: The inclusion of chemical or peptide motifs in a probe to direct its accumulation within specific subcellular compartments.

References

1. Two-photon fluorescent chemosensors based on the GFP-chromophore for the detection of Zn2+ in biological samples – From design to application. Sensors and Actuators B Chemical (2024).
2. Reversible fluorescent solid porous films for detection of zinc ions in biological media. Journal of Biological Engineering (2025).
3. Simultaneous Zn2+ tracking in multiple organelles using super-resolution morphology-correlated organelle identification in living cells. Nature Communications (2021).
4. Real Time Imaging and Dynamics of Hippocampal Zn2+ under Epileptic Condition Using a Ratiometric Fluorescent Probe. Scientific Reports (2018).