Preparation and application of lysozyme aptamer fibre for specific recognition of lysozyme in food samples

A novel aptamer solid-phase microextraction (SPME) fibre-based on poly (methacrylic acid-co-ethylene glycol dimethacrylate) for lysozyme-specific recognition has been successfully prepared. The prepared SPME fibres were characterised by various instrumental methods, including scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectrometry. The results showed that the SPME fibre exhibited a porous structure, which is beneficial for the enrichment of the aptamer. The solid-phase microextraction-high-performance liquid chromatography-fluorescence detection (SPME-HPLC-FLD) with the superior selectivity and sensitivity responded linearly to the concentration of lysozyme over the 0.025–10 mg/L range, and the limit of detection was low at 6.8 μg/L, with a linearity of 0.9995. The method showed excellent reproducibility, and the relative standard deviations (RSDs) were less than 5.5%, which facilitated the analysis. The method was applied for the analysis of lysozyme in cow milk and papaya samples, and the recoveries ranged from 86.7–93.5% with RSDs of 4.3–6.1%, which clearly state that the proposed lysozyme aptamer SPME-HPLC-FLD method is a promising analytical tool for the analysis of lysozyme in food samples.