A chemical analysis of ceramic fragments from a Kushan-era settlement in Northwest India has revealed the earliest known application of nanostructured silver for water treatment. Published in Archaeological and Anthropological Sciences, the study suggests that ancient potters intentionally incorporated silver ions into the porous lining of water jars to prevent bacterial growth.
Researchers utilized electron microscopy to identify the silver nanoparticles, which appear to have been stabilized using botanical extracts. This finding suggests a sophisticated understanding of metallurgy and chemistry, indicating that "silver-water" purification protocols mentioned in later Ayurvedic texts were already in industrial use by the 2nd century CE.