Rapid pathogen detection with bacterial-assembled magnetic mesoporous silica

• Rapid pathogen detection was achieved by bacteria-assembled Ni2+-functionalized magnetic cmesoporous silica (Ni-HMMS).
• High efficiency of pathogen detection was used by water-borne pathogen E. coli O157:H7.
• Direct and rapid RT-PCR to quantitative detection was demonstrated without bacterial amplification and DNA extraction step
• High sensitive detection at untralow concetration (1 Log10 cfu mL−1) was achieved with real samples.

We report rapid and accurate pathogen detection by coupling with high efficiency magnetic separation of pathogen by Ni2+-heterogeneous magnetic mesoporous silica (Ni-HMMS) and real time-polymerase chain reaction (RT-PCR) technique. Ni-HMMS was developed with a significant incorporation of Fe particles within the silica mesopores by programed thermal hydrogen reaction and functionalized with Ni2+ ion on the surface by the wet impregnation process. High abundant Ni2+ ions on the Ni-HMMS surface were able to assemble with cell wall component protein NikA (nickel-binding membrane protein), which contains several pathogenic bacteria including Escherichia coli O157:H7. NikA protein expression experiment showed the outstanding separation rate of the nikA gene-overexpressed E. coli (pSY-Nik) when comparing with wild-type E. coli (44.5±13%) or not over-expressed E. coli (pSY-Nik) (53.2±2.7%). Moreover, Ni-HMMS showed lower obstacle effect by large reaction volume (10 mL) than spherical core/shell-type silica magnetic nanoparticles functionalized with Ni2+ (ca. 40 nm-diameters). Finally, the Ni-HMMS was successfully assessed to separate pathogenic E. coli O157:H7 and applied to direct and rapid RT-PCR to quantitative detection at ultralow concentration (1 Log10 cfu mL−1) in the real samples (milk and Staphylococcus aureus culture broth) without bacterial amplification and DNA extraction step.

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