“…22,[29][30][31][32] When entering a natural environment, the nanoparticles are interacting with the surrounding biomolecules forming large heteroaggregates, [33][34][35][36] which may affect the toxicity of the nanoparticle. 33,34,36 The interactions change the presented surface chemistry as the particles are covered with various biomolecules. This is interesting as positively charged model polystyrene nanoparticles are reported to be more toxic than negatively charged ones, 29,34,36 although the effect of the interactions differ.…”