Alexandra Garraud, Camilo Velez, Yash Shah, Nicolas Garraud, Bettina Kozissnik, Elena G. Yarmola, Kyle D. Allen, Jon Dobson, and David P. Arnold, University of Florida, USA
There is great interest for using magnets to trap micro- and nano-scale magnetic particles from biological fluid samples or even recover particles from within the body. It is well known that magnetic particles can be functionalized to bind with specific targets such as inflammatory mediators, peptide and protein biomarkers, or even cells. However, it is uncertain if magnetic capture approaches are feasible for recovering particles from high-viscosity fluids, since the viscous drag forces acting on a particle may lead to impractical capture times.
In this article, we study the efficacy of particle capture using small, high-field-gradient permanent magnets, with particular emphasis on high-viscosity fluids mimicking the synovial fluid found in articulating joints. This study is part of a larger effort aimed at developing a method to recover osteoarthritis biomarkers from small joint spaces (e.g. rodent animal models, or human finger joints) without the need for synovial fluid taps.
Numerical simulations and in vitro experiments are performed with millimeter-scale magnets collecting magnetic particles from fluids with viscosities ranging thousand-fold, from that of water (0.86 mPa·s) to synovial fluid (770 mPa·s). The magnetic particles are composite iron-oxide nanoparticle/polystyrene magnetic beads with a hydrodynamic diameter of 800 nm. The simulations and experiments confirm the feasibility of collecting clinically relevant numbers of particles from small joint spaces.
Keywords: biomagnetics; magnetic forces; biological fluids; magnetic particles; osteoarthritis