TRACKING UPTAKE AND TOXICITY OF NANOPARTICLES IN HUMAN ENDOTHELIAL CELLS IN STATIONARY AND FLOW CONDITIONS

The increasing use of metal nanoparticles (NPs) as new multi-functional platform for diagnostic and drug delivery requires studies that characterize their properties and potential cytotoxic effects. In this work we investigate the uptake and nanotoxicity of gold NPs towards cells of the vascular system (HUVEC, Human Umbilical Vein Endothelial Cells) in stationary vs flow conditions, realized via polydimethylsiloxane (PDMS) microfluidic devices (MFDs). The continuous perfusion provided by a microfluidic system simulates the physiological characteristics of the circulatory system. Optical properties of NPs are studied by UV-Vis spectroscopy, providing information about aggregation/modification promoted by exposure to cell-growth medium. The characterization of dimension and shape of NPs is accomplished by transmission electron microscopy (TEM) and Two-Photon Fluorescence Correlation Spectroscopy (TP-FCS), successfully used for the determination of the average hydrodynamic radius. TEM analysis of HUVEC cells treated with NPs reveals that they are localized in cytoplasmic endosomes, as single NPs or at most as small aggregates. The assessment of viability of HUVEC cells grown in multiwells or in MFD and exposed to NPs, is measured by Trypan Blue exclusion test and Live/Dead Cell Viability Assay: the data show that NPs toxicity is not time-dependent but dose-dependent. Moreover, in MFD is detected a lower cytotoxicity: the flow exposure avoids the gravitational setting of particles and promotes their homogeneous distribution in the culture medium. These results provide new useful information to evaluate the toxicity and therapeutic efficacy of drugs intravenously administrated by means of nanoparticle-based formulations.