ZnO nanoparticle-modified polymethyl methacrylate-assisted dispersive liquid–liquid microextraction coupled with MALDI-MS for rapid pathogenic bacteria analysis

Abstract

A new and fast nano-based approach to extract pathogenic bacteria lysates from aqueous samples is reported. Zinc oxide nanoparticles modified with polymethyl methacrylate (ZnO@PMMA) were synthesized and applied to dispersive liquid–liquid microextraction (DLLME) in order to detect and extract bacteria. The extracted lysates were further identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The results indicated that the presented approach is a simple, rapid and efficient microextraction technique for the analysis of pathogenic bacteria lysate (Staphylococcus aureus and Pseudomonas aeruginosa). Under optimal conditions, the minimum detectable concentrations are 9.7 × 10³ and 1.7 × 10⁴ cfu mL⁻¹ for S. aureus and P. aeruginosa, respectively. The ZnO@PMMA nanoparticles provide multifunctional forces to strengthen the interactions with the cell lysate. The large surface area of ZnO@PMMA enhances the separation efficiency and improves the sensitivity and quality of MALDI-MS spectra. The method was validated by the analysis of real samples, such as tap and drinking water. Data revealed that ZnO@PMMA-DLLME is a promising microextraction technique for pathogenic bacteria analysis, which may be utilized in clinical investigations in the near future.