The Impact of the Physiochemical Properties of Manufactured Nanoparticles on In vitro and In vivo Evaluation of Particle Toxicity

Masanori Horie and Hitoshi

Abstract

Recently, many in vitro studies evaluating the effects of nanoparticles on cellular physiology have been reported. In in vitro systems, the nano-objects induce not only primary effects but also confounding (artificial) effects. Investigations into the physiological and pathological effects induced in cells by in vitro exposure to nano-objects may be confounded by the specific physical and chemical properties of the objects. For example, protein adsorption from the culture media to the surfaces of nano-objects can essentially starve the cells. In addition, certain nanoparticles can release metal ions into cell culture or bioassay reagents. The protein adsorption and metal ion release by the nano-objects can interfere with ELISA and LDH assays, producing inaccurate results. Moreover, unstable or non-homogenous suspensions of nano-objects can result in imprecise in vitro evaluations of nano-objects. For accurate in vitro testing of nanoparticles, we should consider the effects of these three important properties of nanosuspensions: protein adsorption, metal ion release, and suspension stability.