Biokinetics of Nano-sized Particles. While many uptake and translocation routes have been demonstrated, others still are hypothetical and need to be investigated. Largely unknown are translocation rates as well as accumulation and retention in critical target sites and their underlying mechanisms. These as well as potential adverse effects will be largely dependent on physicochemical characteristics of the surface and core of nano-sized particles. Both qualitative and quantitative changes in nano-sized particles' biokinetics in a diseased or compromised organism need also to be considered. Reproduced with permission from Environmental Health Perspectives.