Enzyme-driven fluorescence quantification of micro and nanoplastics

Accurate detection of micro- and nanoplastics (MNPs) remains challenging due to analytical limitations, particularly for nanoplastics(<1 μm). Here, we introduce a rapid and simple fluorescence-based method for MNP quantification using a plastic-degrading enzyme. Target plastics are enzymatically depolymerized to generate specific degradation products, which are subsequently quantified via fluorescence measurement. The method enables selective detection of polyethylene terephthalate (PET) and other terephthalate-releasing plastics across a broad size range, from microplastics to nanoplastics. After removal of divalent cations, the assay provides results within 6 h of enzymatic reaction with LODs of 0.43 mg/L and 0.04 mg/L for microplastics (90 μm) and nanoplastics (0.2 μm) PET standards, respectively; concentrations are reported as PET-equivalent mass referenced to these size-matched standards. Quantitative results showed good agreement with orthogonal reference methods - micro-Fourier transform infrared spectroscopy for microplastics and pyrolysis-gas chromatography/mass spectrometry for nanoplastics. This approach provides a practical alternative for rapid MNPs analysis and offers improved accessibility for nanoplastics, supporting its high throughput use in laboratories without specialized instrumentation, for aqueous samples of low matrix complexity.