Grouping of colloidal metal nanoparticles based on their measurable characteristics: A proposed framework

There is a need to take a broader look of nanotoxicological studies. Eventually, the field will demand some generalizations to be made. To begin to address this issue, we posed the question: Are metal colloids on the nanometer size scale a homogeneous group? In general, most people can agree that the physicochemical properties of nanomaterials can be linked and related to their induced toxicological responses. The focus of this study was to study how a set of selected physicochemical properties of five specific metal-based colloidal materials on the nanometer size scale - silver, copper, nickel, iron, and zinc - could be used as nanodescriptors that facilitate the grouping of these metal-based colloids. These particles represent an important category of nanomaterials that are currently mass produced. Each has been reputed to induce toxicological and/or cytotoxicological effects. Here, we propose an experimental methodology coupled with mathematical modeling that can serve as a prototype for a rigorous framework that aids in the ability to group nanomaterials together and to facilitate the subsequent analyses of trends in data based on quantitative modeling of nanoparticle´s structure activity relationships.