Quantum Diamond Microscopy of Individual Vaterite Microspheres Containing Magnetite Nanoparticles

Area of Science:

• Materials Science
• Biomedical Engineering
• Quantum Sensing

Background:

• Vaterite microspheres are porous, biocompatible carriers for magnetic nanoparticles (MNPs).
• MNPs within microspheres are vital for applications like targeted drug delivery and diagnostic imaging.
• Precise control over the magnetic moment of these microspheres is essential for effective biomedical use.

Purpose of the Study:

• To precisely map the stray magnetic fields of individual vaterite microspheres loaded with Fe3O4 MNPs.
• To investigate the influence of MNP size (5 nm, 10 nm, 20 nm) on the magnetic moment of vaterite microspheres.
• To correlate magnetic imaging results with MNP distribution and magnetization uniformity.

Main Methods:

• Widefield quantum diamond microscopy was employed to image stray magnetic fields.
• Over 35 vaterite microspheres (3-10 μm) containing Fe3O4 MNPs were analyzed.
• A 222 mT external magnetizing field was applied, and peak-to-peak stray field amplitudes were measured.

Main Results:

• Microspheres with 5 nm and 10 nm superparamagnetic MNPs showed peak-to-peak stray field amplitudes of 41 ± 1 μT.
• Microspheres with 20 nm ferrimagnetic MNPs exhibited lower amplitudes of 12 ± 1 μT.
• Finite-element simulations indicated variations in MNP distribution and magnetization within the vaterite matrix.

Conclusions:

• Quantum diamond microscopy provides high-resolution magnetic imaging of MNP-loaded vaterite.
• MNP size significantly impacts the magnetic response of vaterite microspheres.
• This technique enables optimized synthesis and development of magnetically controlled systems for precision medicine.