Scientists from the Singapore-MIT Alliance for Research and Technology (SMART) have unveiled a pioneering nanosensor that enables real-time, non-destructive detection of iron in plants, a breakthrough that could transform precision agriculture and sustainable farming practices.
Developed by SMART’s Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) interdisciplinary research group in collaboration with Temasek Life Sciences Laboratory (TLL) and the Massachusetts Institute of Technology (MIT), the near-infrared (NIR) fluorescent nanosensor is the first of its kind to simultaneously detect and differentiate between Fe(II) and Fe(III) – the two primary forms of iron essential for plant health.
Iron plays a crucial role in photosynthesis, respiration, and enzyme function. While Fe(II) is readily available for plant absorption, Fe(III) must first be converted into Fe(II) before plants can utilise it. Traditional methods measure only total iron content, overlooking the distinction between these oxidation states – a critical factor in plant nutrient uptake and metabolism.
“This breakthrough sensor is the first of its kind to detect both Fe(II) and Fe(III) in living plants with real-time, high-resolution imaging,” said Dr Duc Thinh Khong, DiSTAP research scientist and co-lead author of the study. “With this technology, we can ensure plants receive the right amount of iron, improving crop health and agricultural sustainability.”
The nanosensor, which has been successfully tested on spinach and bok choy, is species-agnostic, meaning it can be applied across various plant species without genetic modification. By offering real-time monitoring of iron uptake and transport, the technology allows farmers to diagnose iron deficiencies and optimise fertilisation strategies, ultimately reducing waste and environmental impact.
The research, published in Nano Letters, leverages SMART DiSTAP’s expertise in plant nanobionics and the Corona Phase Molecular Recognition (CoPhMoRe) platform developed at MIT. The nanosensor consists of single-walled carbon nanotubes (SWNTs) wrapped in a fluorescent polymer that interacts differently with Fe(II) and Fe(III). When introduced into plant tissues, it emits distinct NIR fluorescence signals based on the iron type, enabling precise tracking of iron movement and chemical changes.
“This sensor provides a powerful tool to study plant metabolism, nutrient transport, and stress responses,” said Professor Daisuke Urano, TLL senior principal investigator and co-corresponding author of the paper. “It supports optimised fertiliser use, reduces costs and environmental impact, and contributes to more nutritious crops, better food security, and sustainable farming practices.”
Beyond Agriculture: Potential Applications in Health and Environment
The nanosensor’s applications extend beyond agriculture. Researchers believe it holds promise for environmental monitoring, food safety, and health sciences, particularly in studying iron metabolism, iron deficiency, and iron-related diseases in humans and animals. Future research aims to integrate the nanosensor into automated nutrient management systems for hydroponic and soil-based farming, as well as expand its capabilities to detect other essential micronutrients.
“This new tool will not just help farmers detect nutrient deficiency but also give access to certain messages within the plant,” said Professor Michael Strano, DiSTAP Co-Lead Principal Investigator and Carbon P. Dubbs Professor of Chemical Engineering at MIT. “It expands our ability to understand plant responses to their growth environment.”
Supported by the National Research Foundation under its Campus for Research Excellence and Technological Enterprise (CREATE) programme, this innovation marks a significant step towards more sustainable and efficient agricultural practices worldwide. 
