Together with the company BRAVE Analytics, researchers at TU Graz have developed a method for detecting nanoplastics in liquids and determining their composition.

Microplastics and the much smaller nanoplastics enter the human body in various ways, for example through food or the air we breathe. A large proportion is excreted, but a certain amount remains in organs, blood and other body fluids. In the FFG bridge project Nano-VISION, which was launched two years ago together with the start-up BRAVE Analytics, a team led by Harald Fitzek from the Institute of Electron Microscopy and Nanoanalysis at Graz University of Technology (TU Graz) and an ophthalmologist from Graz addressed the question of whether nanoplastics also play a role in ophthalmology. The project partners have now been able to develop a method for detecting and quantifying nanoplastics in transparent body fluids and determining their chemical composition. As an exemplary application of the method, the research team is investigating whether intraocular lenses release nanoplastics. There have been no such studies to date, and initial results have already been submitted to a scientific journal.

Scattered laser light reveals concentration and composition

Micro- and nanoplastics are detected in two steps. The sensor platform developed by BRAVE Analytics draws in the liquid to be analysed and pumps it through a glass tube. There, a weakly focused laser is shone through the liquid in or against the direction of flow. If the light hits any particles, the laser pulse accelerates or decelerates them – larger particles more strongly than smaller ones. The different velocity values allow conclusions to be drawn about the size of the particles and their concentration in the liquid. This method, called optofluidic force induction, was developed by Christian Hill from BRAVE Analytics at the Medical University of Graz.

What is new is the combination of optofluidic force induction with Raman spectroscopy. Now the spectrum of the laser light scattered by individual particles in the liquid is also analysed. A small part of the light, the so-called Raman scattering, has a different frequency to the laser itself and thus allows conclusions to be drawn about the composition of the particles. “Depending on the material of the focused particles, the frequency values are slightly different in each case and thus reveal the exact chemical composition,” says Raman spectroscopy expert Harald Fitzek. “This works particularly well with organic materials and plastics.”

Intraocular lenses: Tests on the possible presence of nanoparticles

The Institute of Electron Microscopy and Nanoanalysis is currently conducting further investigations into the extent to which intraocular lenses yield nanoplastics spontaneously, after mechanical stress or when exposed to laser energy. The findings from these tests are extremely important for ophthalmic surgeons and lens manufacturers.

“Our method for detecting micro- and nanoplastics can be applied to clear body fluids such as urine, tear fluid or blood plasma,” says Harald Fitzek. “However, it is also suitable for the continuous monitoring of liquid flows in industry as well as drinking and waste water.”