Modeling of the Bacteria attached with Magnetic Nanoparticles for Optimization of Magnetic Separation Process

Abstract. Magnetic separation has been used to pretreat samples to capture, separate, and concentrate biological targets in complex samples for further detection. Some simulation models have been developed to predict the magnetic forces applied on magnetic particles (MPs), but very little focus on the complexes of MNPs with biological targets. In this research, a simulation model was developed with the help of Comsol Multiphysics software to describe the magnetic properties of biomolecules coated with magnetic particles to optimize magnetic separation. The model was constructed based on the properties of bacterial cells incorporated with a magnetic separation device. E. coli O157:H7 was used to represent antigenic targets. Experiments in this study were conducted to determine some model parameters and to validate the model. The results showed that the developed model could be used to optimize the magnetic separation in terms of separation efficiency and time based on MP size and surface modification, properties of the biological target, and the magnetic separation device. For one case using E. coli O157:H7 covered with 150 nm MPs, the simulation results indicated that the separation time was 1.3 min traveling 9 mm with a 1.3 T magnetic field strength. The experimental results using the same conditions showed that E. coli O157:H7 had a 91.6% separation efficiency when using 3 min for separation time. Any optimization to increase efficiency and lower time would greatly improve upon current research methods. The model in this research provides a powerful tool in the optimization of magnetic separation involving E. coli with a great potential for other bacteria, viruses, and cells.