A non-destructive way to locate microplastics in body tissue

Microplastics — plastic particles smaller than 5 mm — enter the human body via air, water or food. Their effects on health are the subject of intensive research, but a key challenge to date has been that the available analytical methods either destroy tissue in the body or do not allow conclusions to be drawn about the exact location of the particles.

Now, as part of two research projects, scientists from the Medical University of Vienna (MedUni Vienna) together with partner institutions have established a groundbreaking method that locates microplastics in tissue in a non-destructive and spatially resolved manner — ie, in such a way that the exact location of the particles within the intact tissue structure remains visible. The team’s research, published in the journals Analytical Chemistry and Scientific Reports, could help clarify possible links between microplastic exposure and chronic diseases.

The studies were conducted in cooperation with the Research Centre for Non-Destructive Testing GmbH (RECENDT), where the method known as optical photothermal infrared spectroscopy (OPTIR) is already being used in other contexts. OPTIR was originally developed to visualise chemical structures in complex materials with high spatial resolution. As part of the recent research, the scientific team led by MedUni Vienna’s Lukas Kenner has demonstrated how the method can be applied to human tissue samples.

OPTIR utilises the reaction of different materials to infrared laser light. This light heats the samples locally, whereby plastics such as polyethylene (PE), polystyrene (PS) or polyethylene terephthalate (PET) behave in a manner characteristic of their chemical structure. These specific signals are detected by a second light source, creating a so-called infrared fingerprint that allows unique chemical identification — without damaging the tissue.

The method has now been successfully applied to formalin-fixed and paraffin-embedded (FFPE) samples — the type of tissue that is routinely examined and archived in clinical pathology. The tissue structure remains completely intact, making it possible to combine chemical analysis directly with subsequent histological (microscopic) or genetic assessments. This means that microplastic particles can not only be detected, but also examined in connection with tissue changes.

“In the recently published study, we were able to identify various microplastic particles in human colon tissue, including PE, PS and PET; these were found to be conspicuously frequent in areas with inflammatory changes,” Kenner said. Additional experiments with mice and three-dimensional cell cultures also showed that even extremely small particles with a diameter of only 250 nm can be reliably detected.

“The application of OPTIR technology that we have established shows … precise chemical identification and preservation of spatial tissue information — a milestone for medical microplastics research,” Kenner added.

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