Optimization of Pathogen Capture in Flowing Fluids with Magnetic Nanoparticles

Abstract

Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h(-1) . Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (ce ), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications.

Removal of Cells from Body Fluids by Magnetic Separation in Batch and Continuous Mode: Influence of Bead Size, Concentration, and Contact Time

“…It is estimated that this is the requirement necessary to achieve good separation. 24 One can see how in a couple of minutes all the cells contain at least 10 beads. Because particles are much smaller than cells in that case, the relative movements of particles are much faster, and cells can almost be considered as stationary phase.…”

Optimization of Micromagnetic Separation for Bacteremia Treatment

“…As discussed by Kang et al [19], the concentration of bound bacteria, 0 , as a function of microsphere radius and incubation time is given by…”

“…Miller et al were the first to incorporate an extracorporeal pathogen removal device into an infection model [14]. A magnetic separation model was developed by Kang et al for their device, interrogating the role of the radius of their magnetic beads in separation efficiency from whole blood [19]. Combining these models allows for better understanding of the pharmacokinetics of extracorporeal pathogen removal via magnetic beads and can inform the selection of bead radius, incubation times, and device flow rates.…”

Modeling Superparamagnetic Particles in Blood Flow for Applications in Magnetic Drug Targeting

“…There have been numerous promising trials [1,2] and models of the behavior of ferrofluids intended for applications in retinal detachment restoration [3][4][5], magnetic separation for fluid filtering [6,7], drug therapy for in-stent restenosis [8], and localized cancer treatment [9][10][11][12][13][14] validating the plausibility of this method.…”