The growing development of nanotechnology has promoted the wide application of engineered nanomaterials, raising immense concern over the toxicological impacts of nanoparticles on the ecological environment during their transport processes. Nanoparticles in aquatic systems may undergo deposition onto environmental surfaces, which affects the corresponding interactions of engineered nanoparticles (ENPs) with other contaminants and their environmental fate to a certain extent. In this review, the most common ENPs, i.e., carbonaceous, metallic, and nonmetallic nanoparticles, and their potential ecotoxicological impacts on the environment are summarized. Colloidal interactions, including Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO forces, involved in governing the depositional behavior of these nanoparticles in aquatic systems are outlined in this work. Moreover, laboratory approaches for examining the deposition of ENPs on collector surfaces, such as the packed-bed column and quartz crystal microbalance (QCM) method, and the limitations of their applications are outlined. In addition, the deposition kinetics of nanoparticles on different types of surfaces are critically discussed as well, with emphasis on other influencing factors, including particle-specific properties, particle aggregation, ionic strength, pH, and natural organic matter. Finally, the future outlook and challenges of estimating the environmental transport of ENPs are presented. This review will be helpful for better understanding the effects and transport fate of ENPs in aquatic systems. Graphical abstract ᅟ.

The in vitro labeling of stem or therapeutic cells with engineered nanoparticles with the aim of transplanting these cells into live animals and, for example, noninvasively monitoring their migration, is a hot topic in nanomedicine research. It is of crucial importance that cell-nanoparticle interactions are studied in depth in order to exclude any negative effects of the cell labeling procedure. To date, many disparate results can be found in the literature regarding nanoparticle toxicity due to the great versatility of different parameters investigated. In the present work, an overview is presented of different types of nanomaterials, focusing mostly on iron oxide nanoparticles, developed for biomedical research. The difficulties in assessing nanoparticle-mediated toxicity are discussed, an overview of some of the problems encountered using commercial (dextran-coated) iron oxide nanoparticles is presented, several key parameters are highlighted and novel methods suggested--emphasizing the importance of intracellular nanoparticle degradation and linking toxicity data to functional (i.e., cell-associated) nanoparticle levels, which could help to advance any progress in this highly important research topic.