MagNanoTrap enrichment empowers ultra-sensitive quantification of mixed nanoplastic particles from environmental water samples.

Detection and quantification of nanoplastic particles (NPs) in environmental water are important for monitoring NPs' fate and assessing health impacts, but the lack of sensitive and universal detection systems hinders regulation according to the EU Commission (Allan, J. et al., 2021). The MagNanoTrap termed enrichment platform is based on a bifunctional peptide (LCI-DZ-MBP1) combined with FeO superparamagnetic nanoparticles (SPIONs); the bifunctional peptide was designed to decorate SPIONs for NPs capture, with the LCI-peptide binding to SPIONs and the MBP1-peptide acting as a general binder for polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyethylene terephthalate (PET) particles. The MagNanoTrap enrichment platform, with a maximum MagNanoTrap adsorption capacity of 3.95 ± 0.14 g/g for PS-COOH NPs, enables in combination with pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to reliably determine the composition of mixed NPs and quantify NP amounts down to 0.061 µg for PS. The achieved sensitivity ensures that a 1 L water sample is usually sufficient to detect and quantify NPs in environmental water samples, requiring only 16 mg of LCI-DZ-MBP1 coated SPIONs. The high affinity and general applicability of MagNanoTrap against NPs are ensured through high salt ion concentration, which makes hydrophobic interactions the main binding force. Proof of concept for versatile use of the MagNanoTrap enrichment platform was successfully performed by enrichment and quantification of mixed NPs, including PP, PS, PE, PET, poly (methyl methacrylate), polycarbonate, nylon 6, and nylon 66, across seven types of environmental water samples from rivers, lake, sea, and wastewater sources.