(113b) Magnetic Nanoparticle Characterization and Quantification of Endocytosis Mechanisms By Particle Tracking Velocimetry

The properties of individual magnetic particles are of utmost importance in determining their fate in different biomedical and toxicology applications. Utilizing the particle tracking velocimetry in dark-field imaging we were able to quantify the magnetophoretic mobility distributions and intrinsic magnetic properties of individual magnetic particles. In this study, we have quantified the number of superparamagnetic iron oxide nanoparticles (SPIONs) ingested per cell and the kinetics of in vitro receptor-independent endocytosis of different particles with cultured Chinese hamster ovary (CHO-K1) cells. Magnetophoretic mobility of the CHO-K1 cells ingested with different SPIONs is directly proportional to the cellular uptake (beads per cell). The average magnetophoretic mobility for a particular sample is shown to be dependent on the particle surface chemistry, time of incubation, and particle concentration. The dominant endocytic pathway for each particle type has been determined using the specific inhibitors, genistein and chlorpromazine for caveolae and clathrin-dependent endocytic mechanisms respectively. The toxicity of these two specific inhibitors and their effect on CHO-K1 cell viability was quantified by magnetophoretic mobility measurements. This time-efficient magnetic characterization is useful in quantifying the magnetic properties of individual nanoparticles, their cellular uptake, and helps in the selection of particle surface chemistry for cellular endocytosis.