Oldamur Hollóczki, Bonn: On the environmental effects of nanoplastics

When: Mon, 18.1.2021, 16:00

Where: Online via Moodle Collaborate

Throughout the last decade there has been an increasing scientific and public concern regarding the environmental effects of plastic wastes, especially that of smaller fragmentation products: micro- and nanoplastics. Nanoplastics, with a diameter < 100 nm, have been reported to enter the bodies and organs of animals and humans, but until very recently little was known about the extent of their actual effects. The difficulties of the corresponding research lie in the challenging detection of these small, mostly organic species in colloidal solutions of similarly sized biomolecules.

To tackle these problems, we applied molecular modeling and theoretical chemistry for exploring nanoplastic-biomolecule interactions. We found that these particles may spontaneously enter change the structure and dynamics of lipid bilayers [1, 2], including the blood-brain barrier [2], which can have severe effects on the environment and on human health as well. Furthermore, we demonstrated that upon interacting with nanoplastics the secondary structure of proteins can be altered [3, 4]. In the presence of plastic particles, β-loop-like tryptophan zippers show significant changes in the energy demand of cleaving the intramolecular hydrogen bonds that define the structure of these de novo proteins. Polyethylene nanoparticles apparently stabilize α-helices, which they also encompass through the rearrangement of the constituting polymer chains [3, 4]. Nylon, on the other hand, spontaneously changes α-helices into a more β-sheet like assembly [3, 4]. Since such changes are responsible for various prion diseases, and have been also related to Alzheimer’s disease, these findings are particularly concerning.

Having seen these severely adverse effects it is clear that technological processes are necessary to be developed for the removal of such particles. We aimed at designing extractants that can be used for this purpose. The first set of solvents in our focus were hydrophobic ionic liquids (ILs) [5]. Within these materials, the ions form micelles around the plastics, but do not of disintegrate them into smaller particles. This feature gives ILs a clear advantage over organic molecular solvents such as THF or toluene, in which the disintegration of nanoplastics produces smaller, and potentially more harmful plastic fragments. The interface of IL and water attracts the charged polar domain of the IL. One might imagine that this structure provides a significant barrier for the phase transfer of the plastic particle, however, as the plastic approaches the interface, the interfacial ions flip over to present their non-polar groups to the particle, allowing the extraction to occur without any activation energy.

Since ionic liquids can be toxic, their use in drinking water and food treatment might be limited to a couple of compounds. For this reason, we are currently extending the scope of extractants also to environmentally more benign solvents.

[1] O. Hollóczki, S. Gehrke, ChemPhysChem 2020, 21, 9-12.
[2] K. Wen, A. S. Keimowitz, O. Hollóczki submitted
[3] O. Hollóczki, S. Gehrke, Sci. Rep. 2019, 9, 16013.
[4] O. Hollóczki Int. J. Quantum Chem. 2020, e26372.
[5] R. Elfgen, S. Gehrke, O. Hollóczki, ChemSusChem 2020, 13, 5449-5459.

Dr. Oldamur Hollóczki, Mulliken Center for Theoretical Chemistry, Universität Bonn, DE


Dr. Oldamur Hollóczki, Mulliken Center for Theoretical Chemistry, Universität Bonn (Copyright: Hollóczki)