Innovative Approach Sheds Light on Microplastic Movement in Living Organisms
As concerns about microplastics continue to mount globally, researchers are making strides in understanding their journey inside the human body. A team led by Associate Professor Masakazu Umezawa from the Tokyo University of Science has pioneered a new method to visualize these particles in real-time, offering fresh insights into their biological impact.
Microplastics, defined as fragments smaller than 5 mm, have infiltrated various environmental mediums such as water, soil, and air, and are even present in everyday items like cosmetics and detergents. With their ability to be ingested or inhaled, these particles pose potential risks to organs including the liver, lungs, kidneys, and brain. Despite their widespread presence, much about their movement within the body remains unclear.
To address this, Umezawa’s team developed fluorescent microplastics that emit light in the second near-infrared (NIR-II) window. This technology enables detailed imaging through deep tissue, tracking the particles’ journey from ingestion to excretion. The findings were published in the journal Environmental Science: Advances in February 2026.
Umezawa remarked, “The issue of MPs has been raised worldwide, and there are several news articles on the web, but the topic of how they move inside the body has not been discussed, and there remain many unclear aspects. I wanted to contribute by proposing a new method to clarify this issue.”
The research team improved upon previous methods by creating more realistic models of irregularly shaped microplastics using common plastics such as polypropylene (PP), polyethylene (PE), and polystyrene (PS). These models were loaded with a fluorescent dye, IR-1061, allowing visualization when administered to mice.
During their experiments, it was observed that these microplastics lingered in the stomach before moving to the intestines and were eventually excreted, with no significant absorption beyond the gastrointestinal tract. The size of the particles influenced their retention time in the intestines.
Further experiments demonstrated the method’s versatility by loading the microplastics with another dye, Nile red, to study cellular uptake. Results indicated that cells absorbed these particles at lower concentrations than previously reported spherical models, suggesting a more nuanced interaction with biological systems.
As global plastic waste is expected to double by 2040, understanding microplastic behavior in organisms is increasingly critical. This new method not only provides a way to study chronic exposure effects but also aids in assessing risks posed by these particles.
Umezawa concluded, “The development of methods for synthesizing NIR-II-fluorophore-loaded microplastic models with various chemical compositions will support risk assessments by providing insights into the environmental and biological fate of MPs.”
These revelations are set to inform future regulatory evaluations of microplastic exposure through food and air.
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DOI: https://doi.org/10.1039/D6VA00031B
About Tokyo University of Science
Tokyo University of Science (TUS) is a leading science-specialized private research university in Japan, promoting scientific advancement since its inception in 1881. Known for its multidisciplinary approach, TUS remains the only private Japanese university with a Nobel Prize laureate in natural sciences. For more information, visit their website.
About Associate Professor Masakazu Umezawa
Dr. Masakazu Umezawa is an esteemed Associate Professor at the Tokyo University of Science. His research focuses on nanomaterials chemistry and environmental physiology, contributing significantly to the scientific community with numerous publications and accolades.
Original Story at www.eurekalert.org