Preparation of silver nanoparticles in inorganic clay suspensions

We have successfully developed a simple method for preparing silver nanoparticles via photoreduction of AgNO3 in layered laponite suspensions without any addition of reduction agent or heat treatment. The properties of silver nanoparticles were studied as a function of the UV irradiation time. A bimodal size distribution and relatively large silver nanoparticles were obtained when irradiated under UV for 3 h. Further irradiation disintegrated the silver nanoparticles into smaller size with a single mode distribution until a relatively stable size and size distribution were achieved. The results from optical absorption spectra of silver nanoparticles agree well with the detailed microstructure studies performed by transmission electron microscopy (TEM). The synthesized laponite suspensions containing silver nanoparticles are stable up to several months and have potential applications as antimicrobial ointments.