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Updated: May 6, 2026
Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System
Published on: June 13, 2010
Rapid pathogen detection with bacterial-assembled magnetic mesoporous silica
Soo Youn Lee1, Jiho Lee, Hye Sun Lee
1Korea Institute of Ceramic Engineering & Technology, Seoul 153-801, Korea.
Abstract:
We report rapid and accurate pathogen detection by coupling with high efficiency magnetic separation of pathogen by Ni(2+)-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 programmed thermal hydrogen reaction and functionalized with Ni(2+) ion on the surface by the wet impregnation process. High abundant Ni(2+) 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 Ni(2+) (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.
Insights
This study introduces a novel method for rapid pathogen detection using magnetic separation with Ni-HMMS and real-time PCR. This technique allows for ultra-low concentration detection of E. coli O157:H7 in real samples without DNA extraction.
Area of Science:
- Materials Science
- Biotechnology
- Analytical Chemistry
Background:
- Pathogen detection is crucial for public health and food safety.
- Current methods often require lengthy procedures like DNA extraction and bacterial amplification.
- There is a need for rapid, sensitive, and efficient pathogen detection techniques.
Purpose of the Study:
- To develop a novel magnetic separation material for efficient pathogen capture.
- To couple this material with real-time PCR for rapid and sensitive pathogen quantification.
- To demonstrate the effectiveness of this method in real-world samples.
Main Methods:
- Synthesis of Ni(2+)-heterogeneous magnetic mesoporous silica (Ni-HMMS) nanoparticles.
- Utilizing Ni(2+) ions on Ni-HMMS to capture E. coli O157:H7 via the NikA protein.
- Direct application of captured bacteria to real-time PCR (RT-PCR) for quantitative detection.
Main Results:
- Ni-HMMS demonstrated high efficiency in separating E. coli O157:H7, especially with NikA overexpression.
- The Ni-HMMS system showed reduced interference in large reaction volumes compared to other magnetic nanoparticles.
- Successful detection of pathogenic E. coli O157:H7 at ultra-low concentrations (1 Log10 cfu mL(-1)) in milk and bacterial broth samples.
- Elimination of the need for bacterial amplification and DNA extraction steps.
Conclusions:
- Ni-HMMS coupled with RT-PCR offers a rapid and accurate method for pathogen detection.
- This approach simplifies sample preparation and reduces detection time.
- The developed method holds significant potential for real-time pathogen monitoring in various sample types.
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