materials and technologies he has developed over the years have been combined to make affordable all-inclusive point-of-use drinking water purifiers, which are being installed in various parts of the country, both as a community and as domestic units. These advanced sand-like composites are made in the water at room temperature, with no environmental cost. Gravity-fed water solutions using such materials without the use of electricity can make sustainable access to safe drinking water a reality. With all these developments, ‘nanomaterials for water purification’ is recognised as one of the major themes of research in the area. Pradeep has shown that completely home-grown nanotechnology, from lab to market is possible in India. His recent discovery of ultrasensitive single-particle sensors with the capacity to detect a few tens of molecules and ions may be combined with new materials to make simultaneous sensing and scavenging at ultra-trace levels possible. The new materials he has developed have been put together to make community purifiers in arsenic affected areas of West Bengal which have been running for seven years. Arsenic-free water is now being delivered to about 10,00,000 people using these technologies. The technology has now been approved for national implementation. He created 3D organised structures of nanoparticles called superlattices and used them for surface enhanced Raman imaging and specific gas sensing applications. In his earlier research, Pradeep discovered that binding of metallic nanoparticles on metallic carbon nanotube bundles made the latter semiconducting and consequently the nanoparticle-nanotube composite became luminescent in the visible region. This luminescence was reversible by the exposure of specific gases such as hydrogen as they occupied the interstitial sites of the bundle. He showed a transverse electrokinetic effect in metal nanoparticle assemblies which resulted in a potential when a liquid was flown over it. Using spectroscopic and scattering techniques, he showed that long chain monolayers on metal nanoparticle surfaces were rotationally frozen. This is in contrast to the monolayers on planar surfaces, which are in a rotator phase at room temperature (RT). All of these results have implications to the applications of nanoparticles in diverse areas. Other aspect of his research is on ice, the solid form of water. He found novel processes occurring at the very top of ice surfaces which are of particular relevance to atmospheric chemistry. Among the various examples, he has shown that the vapour pressures of gases oscillate over melting ice; the study has implications to