While microplastic pollution continues to advance, research into its possible effects on health remains hampered by technical hurdles: to date, there are no suitable methods for precisely identifying the particles in the body without destroying tissue. As part of two research projects, a team of scientists from MedUni Vienna, together with partner institutions, has now established a new, groundbreaking method that locates microplastics in tissue in a non-destructive and spatially resolved manner – i.e. in such a way that the exact location of the particles within the intact tissue structure remains visible. The study results, currently published in the journals Analytical Chemistry and Scientific Reports, could advance research and help clarify possible links between microplastic exposure and chronic diseases.

The studies were conducted in cooperation with RECENDT GmbH – Research Centre for Non-Destructive Testing in Linz, where the method known as OPTIR is already being used in other contexts. OPTIR stands for Optical Photothermal Infrared Spectroscopy and was originally developed to visualise chemical structures in complex materials with high spatial resolution. As part of the recently published research, the scientific team led by Lukas Kenner from the Clinical Department of Pathology at MedUni Vienna has demonstrated for the first time that and how the method can be applied to human tissue samples.

Infrared fingerprinting for precise identification
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.

What makes the newly developed testing concept so special is that the method has been successfully applied for the first time to FFPE samples (formalin-fixed and paraffin-embedded) – 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," reports Lukas Kenner. Additional experiments with mice and three-dimensional cell cultures also showed that even extremely small particles with a diameter of only 250 nanometres – equivalent to 0.00025 millimetres – can be reliably detected. PE, PS and PET are particularly widespread plastics that can be found in many everyday objects such as cling film, plastic bags, drinking bottles and food packaging.