Nanoparticles (NPs) have become more widely used in technology, research, and medicine in recent years. The exploitable biological activities are assumed to be based on the tiny particle size along with their unique chemical and physical characteristics. We take a look at some of the most recent toxicity studies on NPs with clinical relevance. The cha- -lenge of transferring knowledge acquired from cell-based investigations into a human setting is examined, as well as the mechanisms of cytotoxicity. The so-called 'proof-of-principle' approach, in which ultra-high NP concentrations are used to ensure cytotoxicity, is evaluated on the basis of two factors: first, the concentrations used are in no way related to the actual doses required, which, in many cases, discourages further important research
