| Influential factor | Effect for experimental    systems | in vitrotest | in vivotest |  | 
      
        | Adsorption ability
          (Proteins, salts) | Adsorption of molecules to    particles | Yes | Yes | primary effect | 
      
        | Influence of adsorption effect    on experimental result.
          (Starvation effect, adsorption of marker molecules, etc.) | Yes | No | confounding effects
          (artificial) | 
      
        | Metal ion release | Metal ion release from    nanoparticles | Yes | Yes | primary effect | 
      
        | Accumulation of metal ions in experimental    system | Yes | No | confounding effects
          (artificial) | 
      
        | Influence to experimental    reaction such as ELISA | Yes | No | confounding effects
          (artificial) | 
      
        | Stability of nanosuspension | Formation of secondary    particles, aggregates and/or agglomerates | Yes | Yes | primary effect | 
      
        | Accumulation of the large    secondary particles onto cells by gravitational settling | Yes | No | confounding effects
          (artificial) |