Physical aspects of magnetic nanoparticle manipulation in environmental and biomedical applications

Microfluidic manipulation of magnetic nanoparticles (MNPs) is a smart tool for various environmental and biomedical applications. Unfortunately, these techniques have a strong limitation related to the low efficiency of magnetic manipulation of MNPs due to their Brownian motion. However, molecules adsorbed on the surface of MNPs can cause their weak (primary) aggregation. Once the magnetic field is applied, the magnetic force exerted on the primary aggregates will be strongly amplified allowing for significant improvement of the remote control over the MNPs by the magnetic fields. In this paper, we check this concept on three different physicochemical systems covering different application: (i) methylene blue cationic dye adsorbed on citrate coated MNPs for water purification; (ii) curcumin bound to the & beta;-cyclodextrin modified MNPs for magnetic drug delivery; (iii) antigens bound to MNPs decorated with antibodies for model immunoassays. We find striking similarities of the magnetic-field induced behaviours of these different systems, with the dipolar coupling parameter, the supersaturation, the Mason number and the Peclet number being the main governing parameters. We also mention the possibility of using this concept for enhancement of the convective drug transport through the blocked blood vessels.