Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe

Area of Science:

• Biotechnology
• Analytical Chemistry
• Nanotechnology

Background:

• Immunoassays are crucial for detecting biomolecules.
• Electron spin resonance (ESR) spectroscopy offers sensitive detection methods.
• Iron oxide nanoparticles can serve as effective probes in analytical techniques.

Purpose of the Study:

• To develop and validate an immunoassay using iron oxide nanoparticles as ESR probes.
• To investigate the effect of nanoparticle size on assay performance.
• To enhance signal amplification in immunoassay detection.

Main Methods:

• Iron oxide nanoparticles (10 nm and 30 nm) were labeled with antibodies.
• An immunoassay was performed using sepharose beads as the solid phase.
• Electron spin resonance (ESR) spectroscopy was used to detect the iron oxide nanoparticle-labeled antibody-antigen complex.

Main Results:

• The immunoassay successfully detected rabbit IgG antigen.
• Assay sensitivity and detection range were influenced by nanoparticle size.
• 10 nm nanoparticles yielded an upper detection limit of 40.00 μg/mL and sensitivity of 1.81 μg/mL.
• 30 nm nanoparticles showed an upper detection limit of 3.00 μg/mL with varying sensitivity (0.014-0.13 μg/mL).

Conclusions:

• Iron oxide nanoparticles are effective ESR probes for immunoassay signal amplification.
• Nanoparticle size significantly impacts immunoassay detection range and sensitivity.
• This method offers a promising approach for sensitive antigen detection.