Magnetic Particle Spectroscopy with One-Stage Lock-In Implementation for Magnetic Bioassays with Improved...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Nanotechnology

Background:

• Magnetic particle spectroscopy (MPS) is a sensitive technique for bioassays using magnetic nanoparticles (MNPs).
• Existing MPS platforms can be affected by feedthrough signals from external magnetic fields, limiting sensitivity.
• Accurate detection of analytes in liquid phases is crucial for diagnostics and research.

Purpose of the Study:

• To develop a modified MPS platform with a one-stage lock-in design to improve system sensitivity.
• To quantify the detection limits of the enhanced MPS system for different types of magnetic nanoparticles.
• To demonstrate the utility of the enhanced MPS system for bioassay applications, including detecting SARS-CoV-2 spike protein and streptavidin.

Main Methods:

• Implementation of a one-stage lock-in design in the MPS platform to eliminate feedthrough signals.
• Testing the system's sensitivity using multi-core Nanomag50 and single-core SHB30 iron oxide magnetic nanoparticles.
• Application of the enhanced MPS system to detect SARS-CoV-2 spike protein and evaluate streptavidin-biotin binding assays.

Main Results:

• The modified MPS system achieved high sensitivity, detecting as low as 781 ng of multi-core MNPs and 78 ng of single-core MNPs.
• A detection limit of 125 nM (5 pmole) was achieved for SARS-CoV-2 spike protein.
• Single-core MNPs were suitable for Brownian relaxation-based bioassays, unlike multi-core MNPs, and lower MNP amounts improved assay sensitivity.

Conclusions:

• The one-stage lock-in MPS design significantly improves system sensitivity by removing external magnetic field interference.
• The enhanced MPS platform is capable of highly sensitive detection of biomolecules, including viral proteins.
• Optimization of MNP concentration offers a pathway to further enhance bioassay sensitivity using this advanced MPS technology.