Related Experiment Video
Updated: May 28, 2026
09:04
Foodborne Pathogen Screening Using Magneto-fluorescent Nanosensor: Rapid Detection of E. Coli O157:H7
Published on: September 17, 2017
Magnetic core-shell fluorescent pH ratiometric nanosensor using a Stöber coating method.
A Lapresta-Fernández1, T Doussineau, A J Moro
1Institute of Physical Chemistry, Friedrich-Schiller-University Jena, Jena, Germany. lapresta@ugr.es
Analytica Chimica Acta
|October 27, 2011
Summary
We developed magnetic fluorescent sensor nanoparticles for ratiometric pH measurements between pH 5-8. These dual-dye doped silica-coated maghemite nanoparticles offer reliable pH sensing with potential applications in various sample matrices.
Area of Science:
- Nanotechnology
- Materials Science
- Analytical Chemistry
Background:
- Development of novel sensor nanoparticles is crucial for advanced analytical applications.
- Magnetic nanoparticles offer unique advantages for separation and concentration.
- Ratiometric sensing provides enhanced accuracy and stability.
Purpose of the Study:
- To synthesize and characterize magnetic fluorescent sensor nanoparticles for ratiometric pH measurements.
- To embed two distinct fluorophores within silica shells on maghemite cores.
- To evaluate the performance of these nanoparticles in the pH range of 5-8.
Main Methods:
- Modified Stöber method for silica coating of maghemite (γ-Fe(2)O(3)) nanocrystals.
- Incorporation of sulforhodamine B (reference dye) and fluorescein (pH-sensitive dye) into silica shells.
- Characterization using dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM).
Main Results:
- Uniformly sized (50-70nm) silica-coated maghemite nanoparticles were successfully synthesized.
- Nanoparticles exhibited characteristic maghemite spinel structure and satisfactory magnetic properties for separation.
- Ratiometric fluorescence intensity correlated with pH changes in the 5-8 range, with rapid response times.
- The sensing method showed no significant statistical difference compared to a reference procedure in complex matrices.
Conclusions:
- The developed magnetic fluorescent sensor nanoparticles are effective for ratiometric pH sensing.
- The silica coating provides a stable platform for embedding dyes and maintaining nanoparticle integrity.
- The method is robust and statistically validated for use in water, buffer, and serum-containing samples.
Related Concept Videos
03:31Labeling DNA Probes
DNA probes are fragments of DNA labeled with a reporter tag to enable their detection or purification. The resulting labeled DNA probes can then hybridize to target nucleic acid sequences through complementary base-pairing, and may be used to recover or identify these regions.
Radioisotopes, fluorophores, or small molecule binding partners like biotin or digoxigenin, are the most widely used reporter tags for labeling DNA probes. These labels can be attached to the probe DNA molecule via...
Radioisotopes, fluorophores, or small molecule binding partners like biotin or digoxigenin, are the most widely used reporter tags for labeling DNA probes. These labels can be attached to the probe DNA molecule via...
01:25Fluorescence and Phosphorescence: Instrumentation
Fluorometers and spectrofluorometers are two types of instruments used for measuring molecular fluorescence. These instruments differ in how they select excitation and emission wavelengths and the type of light sources they utilize. Fluorometers use absorption interference filters to choose excitation and emission wavelengths. The excitation source in a fluorometer is typically a low-pressure mercury vapor lamp that emits intense lines distributed throughout the ultraviolet and visible regions.