Aggregative stability of colloidal ReVO4:Eu3+ (Re = La, Gd, Y) nanoparticles with different particle sizes

Aggregation behavior of 2 nm, 10 nm × 50 nm, and 8 nm × 80 nm lanthanide orthovanadate nanoparticles under some electrolytes and physiological media influence was investigated. The results have shown that at the same CaCl2 concentration, particles of different sizes show different tendency to aggregate. At the same CaCl2 concentration in solution aggregation rates are higher for smaller particles. The critical coagulation concentration depends on particle size, and decreases as particle size decreases. The coagulation by inorganic electrolytes occurs in accordance with the Schulze-Hardy rule. In the case of organic electrolytes, including colloidal cationic surfactants, their coagulation points decrease with increasing hydrophobicity and surface activity of the cations. We have demonstrated significant effect of media composition (monovalent ions, serum) and thus the importance of NPs characterization under conditions that are representative of cell culture media or physiological conditions for understanding of NPs interaction with biological systems and for assessments of nanoparticle cytotoxicity. Solutions of nanoparticles in an isotonic medium (5% glucose) can be used for parenteral injection in experiments in vivo.