A newly developed fluorescent nanosensor can detect iron species in living plants in real-time, offering a major step forward in understanding iron dynamics and improving nutrient management in agriculture.
Study: Nanosensor for Fe(II) and Fe(III) Allowing Spatiotemporal Sensing in Planta. Image Credit: Filmping/Shutterstock.com
Background
Iron is essential for plant health and growth, yet its uptake, transport, and utilization remain complex and not fully understood. Traditional tools for studying iron movement, while useful in controlled environments, often lack the sensitivity and specificity needed for real-world applications.
Previous research introduced small-molecule fluorescent sensors capable of detecting either Fe(II) or Fe(III), but none could differentiate both oxidation states within a living plant. This limitation has hindered the ability to analyze iron’s redox status and its role in metabolic pathways.
In this study, the researchers aim to address this gap by reviewing advancements in sensor technology and exploring how physiological and environmental factors influence iron transport.
The Current Study
To overcome these challenges, the researchers developed a nanosensor using a technique called Corona Phase Molecular Recognition (CoPhMoRe), which enhances interactions between the sensor and iron species.
The sensor is composed of an anionic poly(p-phenylene ethynylene) (PPE) polyelectrolyte wrapped around single-walled carbon nanotubes (SWNTs). The SWNTs enable near-infrared (NIR) fluorescence detection, reducing interference from plant tissue auto-fluorescence. The nanosensor selectively responds to Fe(II) and Fe(III), producing distinct fluorescent signals for each oxidation state.
To test its effectiveness, the researchers applied iron sources such as FeSO4 and chelated Fe-EDTA to plant leaves. Using time-resolved imaging, they tracked iron movement in real time, detecting responses within five minutes. Surfactants like Triton X-45 facilitated iron diffusion without disrupting the sensor’s function.
Additionally, experiments simulating various physiological conditions—such as iron deficiency and exposure to stress hormones—helped reveal how these factors affect iron transport.
Results and Discussion
The findings confirmed that the nanosensor effectively distinguishes between Fe(II) and Fe(III) in living plants, offering valuable insights into iron uptake kinetics. A key discovery was that iron moves through plant structures much faster than previously thought. Real-time NIR imaging revealed rapid diffusion across foliar tissues, challenging earlier assumptions about the slow uptake of iron through plant cuticles.
Moreover, the results showed that iron uptake and localization depend on both the chemical form of iron and the plant’s physiological state. Plants experiencing iron deficiency displayed an increased response to iron application compared to those under normal conditions or exposed to stress hormones like abscisic acid (ABA). This suggests that the nanosensor could help optimize nutrient management strategies in agriculture by enabling precise, condition-specific interventions.
Another important aspect of the study was quantifying the “apparent spreading rate” of iron within plants. The analysis showed that healthy plants transport iron more efficiently than those under stress, reinforcing the nanosensor’s potential for precision agriculture. By providing real-time monitoring of plant responses to iron supplementation, this technology could improve micronutrient delivery strategies and enhance crop productivity.
Conclusion
This research represents a significant advancement in sensor technology for studying iron dynamics in plants. The nanosensor not only demonstrates high sensitivity but also enables precise tracking of iron distribution within plant tissues. Its ability to provide spatial and temporal data on iron movement makes it a valuable tool for both plant biology research and agricultural applications.
By highlighting differences in iron transport under various plant conditions, this technology could refine nutrient management strategies and support more sustainable agricultural practices. Enhancing our understanding of iron uptake processes may contribute to food security and help address nutrient deficiencies in crops.
Looking ahead, further exploration of nanotechnology in agriculture could lead to even more targeted and effective interventions in plant nutrition and health.
Journal Reference
Khong D. T., Tan G. Z. H., et al. (2025). Nanosensor for Fe(II) and Fe(III) Allowing Spatiotemporal Sensing in Planta. Nano Letters, 25(4), 2316-2324. DOI: 10.1021/acs.nanolett.4c05600, https://pubs.acs.org/doi/10.1021/acs.nanolett.4c05600