Formation of Negatively Charged AgI Colloid Nanoparticles by Condensation
The stability of silver halide colloids is reported to be important for the toxicological outcome. This study shows a well-suited and cheap condensation reaction to obtain negatively charged silver iodide (AgI) nanoparticles without additional stabilization agents. Charged AgI colloids were synthesized from silver nitrate and potassium iodide solutions. An excess of potassium iodide not only imparted a negative charge, but provided a narrow particle size distribution (50 ± 10 nm). The change of optical properties in the colloid was investigated by UV-VIS spectroscopy. A silver iodide exciton absorption band at peak ~421nm (2.93eV), red-shifted over time. The peak at half maximum intensity increased from 13.3nm to 14.8 nm, characterizing the dispersity of AgI colloidal particles. Colloidal particles stabilized after 33 hours. In-situ real-time UV-VIS measurements provide a tool to adjust the particle characteristics and may serve to further optimize the performance in biological applications.
D. Kalnina et al., "Formation of Negatively Charged AgI Colloid Nanoparticles by Condensation", Advanced Materials Research, Vol. 1117, pp. 159-163, 2015