Effects of shear stress on the cellular distribution of polystyrene nanoparticles in a biomimetic microfluidic system

Effects of shear stress on the intracellular uptake of nanoparticles were originally investigated using a calibrated biomimetic microfluidic system (BMS) that mimics the dynamic environment of cells. Positively or negatively charged polystyrene nanoparticles (PSNs) were chosen as a model. PSNs were delivered to HEK 293T and MS1 cell lines using a BMS. To evaluate intracellular uptake of PSNs under static and dynamic conditions (0.5, 1.0, 3.0 dyne/cm(2)), the fluorescence intensity of intracellular PSNs was measured by flow cytometric analysis and confocal laser scanning microscopy. When delivering cationic PSNs to cells, the intracellular uptake increased as the exposure time and PSN concentration increased under both static and dynamic conditions. Under dynamic conditions, the intracellular uptake of cationic PSN was highly increased in both HEK 293T and MS1 cell lines compared to static conditions. However, intracellular uptake of cationic PSNs was maximized when shear stress was at 0.5 dyne/cm(2) and then gradually decreased as the magnitude of fluidic shear stress increased to 3.0 dyne/cm(2). Contrarily, the anionic PSNs showed no significant difference of cellular uptake in presence of shear stress. Thus, shear stress should be considered to investigate the cellular distribution of various nano particles and drug delivery systems. (C) 2015 Elsevier B.V. All rights reserved.