TU Graz detects nanoplastics in body fluids

16 Apr 2025

Process combining Raman with optofluidic force induction now being applied to ophthalmology.

A project at Graz University of Technology (TU Graz) is applying its nanoplastics detection technology to a novel use in ophthalmology.

The technique incorporates Raman spectroscopy, already an attractive technique for detection of small particles thanks to its ability to identify individual chemical species at low concentrations, although one only recently applied to the issue of environmental nanoparticle contamination.

As originally published in Analytical Chemistry, the TU Graz technique combines Raman spectroscopy with mass spectrometry and also optofluidic force induction, a variant of the optical tweezers principle in which a donut-shaped laser directed through a liquid sample pushes particles forward and turns them around the beam's center.

The sizes of optically trapped particles can be assessed from their position in a weakly focused vortex laser beam, commented the project in its paper. Scattered laser light from the targets can then be analyzed by Raman spectroscopy to identify the chemical constituents, while examination with mass spectrometry provides mass and size.

This combination of optofluidic force induction with Raman spectroscopy is a new concept, according to the project.

"Depending on the material of the focused particles, the Raman frequency values are slightly different in each case and thus reveal the exact chemical composition," commented Harald Fitzek from the Graz Centre for Electron Microscopy. "This works particularly well with organic materials and plastics."

Plastic contamination from plastic lenses

Together with commercial partners at spin-out Brave Analytics, the project intends its hybrid platform to assist the global push to identify nanoscale contaminants present in both the environment and within the human body.

Brave Analytics was founded to commercialize the optofluidic force technique in its TU Graz implementation, christened OF2i, and already markets benchtop apparatus for nanoparticle characterization while seeking new applications for the OF2i procedure.

To that end TU Graz is now applying its hybrid technique to a current question in ophthalmology: whether the intraocular lenses (IOLs) implanted in patients for cataract surgery or other medical purposes can release nanoplastics into the patient's system. No such investigations have been made before now, according to the TU Graz researchers.

The Institute of Electron Microscopy and Nanoanalysis at TU Graz is currently investigating the extent to which IOLs yield nanoplastics spontaneously, either after mechanical stress or when exposed to laser energy. "The findings from these tests are extremely important for ophthalmic surgeons and lens manufacturers," noted TU Graz.

Beyond the IOL application, the hybrid OF2i-Raman analysis platform could also be used to monitor possible contamination in other biological materials, as well as playing a part in process control or industrial engineering.

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