Investigation of Inlet Conditions in The Mixing Process of Nanoparticles and Blood in a T-Shaped Microfluidic Reactor with Small Rectangular Cavities.

During the metastasis of cancer cells, circulating tumor cells (CTCs) are released from the primary tumor, reach the bloodstream, and colonize new organs. A potential reduction of metastasis may be accomplished through the use of nanoparticles in micromixers in order to capture the CTCs that circulates in blood. In the present study, the effective mixing of nanoparticles and the blood that carries the CTCs are investigated. The mixing procedure was studied under various inlet velocity ratios and several T-shaped micromixer geometries with rectangular cavities by using computational fluid dynamics techniques. The Navier-Stokes equations were solved for the blood flow; the discrete motion of particles is evaluated by a Lagrangian method while the diffusion of blood substances is studied by using a scalar transport equation. Results showed that as the velocity ratio between the inlet streams increases, the mixing rate of nanoparticles with the blood flow is increased. Moreover, nanoparticles are uniformly distributed across the mixing channel while their concentration is decreased along the channel. Furthermore, the evolution in time of the blood substances in the mixing channel increases with the increase of the velocity ratio between the two streams. On the other hand, the concentration of both the blood substances and the nanoparticles is decreased in the mixing channel as the velocity ratio increases. Finally, the differences in the dimensions of the rectangular cavities seems to have an insignificant effect both in the evolution in time of the blood substances and the concentration of nanoparticles in the mixing channel.

Heavy Metal Adsorption Using Magnetic Nanoparticles for Water Purification: A Critical Review.

Research on contamination of groundwater and drinking water is of major importance. Due to the rapid and significant progress in the last decade in nanotechnology and its potential applications to water purification, such as adsorption of heavy metal ion from contaminated water, a wide number of articles have been published. An evaluating frame of the main findings of recent research on heavy metal removal using magnetic nanoparticles, with emphasis on water quality and method applicability, is presented. A large number of articles have been studied with a focus on the synthesis and characterization procedures for bare and modified magnetic nanoparticles as well as on their adsorption capacity and the corresponding desorption process of the methods are presented. The present review analysis shows that the experimental procedures demonstrate high adsorption capacity for pollutants from aquatic solutions. Moreover, reuse of the employed nanoparticles up to five times leads to an efficiency up to 90%. We must mention also that in some rare occasions, nanoparticles have been reused up to 22 times.

Simulation of magnetic nanoparticles crossing through a simplified blood-brain barrier model for Glioblastoma multiforme treatment.

BACKGROUND AND OBJECTIVES: Glioblastoma multiforme is considered as one of the most aggressive types of cancer, while various treatment techniques have been proposed. Magnetic nanoparticles (MNPs) loaded with drug and magnetically controlled and targeted to tissues affected by disease, is considered as a possible treatment. However, MNPs are difficult to penetrate the central nervous system and approach the unhealthy tissue, because of the blood-brain barrier (BBB). This study investigates numerically the delivery of magnetic nanoparticles through the barrier driven by normal pressure drop and external gradient magnetic fields, employing a simplified geometrical model, computational fluid dynamics and discrete element method. The goal of the study is to provide information regarding the permeability of the BBB under various conditions like the imposed forces and the shape of the domain, as a preliminary predictive tool. METHODS: To achieve that, the three-dimensional Navier-Stokes equations are solved in the margin of a blood vessel along with a discrete model for the MNPs with various acting forces. The numerical results are compared with experimental measurements showing that the model can predict acceptably the flow behavior. RESULTS: The effect of nanoparticles' size, external magnetic field and blood flow in the vessel, on the brain-barrier's permeability are investigated. Three different cases of available area among the endothelial cells per the MNPs' size ratio are also examined, showing that the MNPs' size and available area is not the dominant parameter affecting the permeability of the BBB. The results indicate that the applied magnetic field enhances the drug delivery into the central nervous system (CNS). When larger MNPs (∼100 nm) are exposed to an external magnetic field, the permeability can be improved up to 30%, while it is shown that smaller MNPs (∼10 nm) cannot be driven by the applied magnetic field and in this case the permeability remains relatively unchanged. Finally, the blood flow increase leads to a permeability improvement up to 15%. CONCLUSIONS: The applied magnetic field improves up to 45% the permeability of the BBB for MNPs of 100 nm. The geometric characteristics of the endothelial cells, the nanoparticles' size and the blood flow are not so decisive parameters for the drug delivery into the CNS, compared to the external magnetic force.