PSBP-functionalized fiber-optic SPR sensor for rapid and selective detection of polystyrene nanoplastics

Novel integration of PSBP with fiber SPR sensor for label-free, selective PSNPs detection. • Excellent selectivity against various interferents (heavy metal ions, antibiotics, microalgae, bacteria, etc.) in complex water environments. • Record-high spectral response of 72 nm within 8 minutes, surpassing existing nanoplastics sensors (<10 nm). This study proposes a fiber optic surface plasmon resonance (SPR) sensor integrated with polystyrene-binding peptide (PSBP) to enable the rapid and selective detection of polystyrene nanoplastics (PSNPs) in aqueous environments. PSBP immobilizes PSNPs onto the fiber surface via strong hydrophobic interactions, π-π stacking, and electrostatic forces, leading to SPR spectral modulation and specific detection. A strong linear correlation between the SPR wavelength shift and the concentration of PSNPs is observed over the range of 5-25 mg/mL, yielding a sensitivity of 3.458 nm/(mg/mL) and a correlation coefficient (R 2 ) of 0.987. For 300 nm PSNPs, the sensor achieves a stable spectral response within 8 min. Notably, the maximum spectral response of the sensor reaches 72 nm, significantly surpassing the limitation of less than 10 nm saturation shift reported in most existing PSNPs sensors. Furthermore, tests involving various typical interfering substances and temperature variations in water demonstrate that the sensor possesses excellent anti-interference capability. The sensor developed in this study exhibits rapid response, pronounced spectral variation, high specificity, and good environmental stability.