Single step synthesis of highly stable good quality water soluble semiconductor/dendrimer nanocomposites through irradiation route

Gamma irradiation method has been used successfully to prepare nanocrystalline CdS/dendrimer nanocomposites in both aqueous and non-aqueous media at room temperature under ambient pressure. Sodium thiosulfate and carbon disulfide were used as sulfur sources in aqueous solution or in methanol. To the best of our knowledge, this is the first report of room temperature synthesis of semiconductor/dendrimer nanocomposites through gamma irradiation route. The sizes of CdS nanoparticles within the nanocomposites were found to be 3.1 and 2.9 nm in water and methanol, respectively, under identical conditions. Dependence of generation, core and surface functionality of dendrimer on particle size, distribution and also on surface charge has been investigated. Small area electron diffraction (SAED) pattern shows that different phase of CdS nanocrystallites in the composite materials can be generated in the present method if sulfur source is varied. Interestingly, in contrast to the available methods, the present radiolytic process has enabled to produce CdS nanoparticles within the dendrimer matrix with narrow size distribution (as low as 6%) along with increased stability. Our adopted method is suitable for synthesis of nanocomposites in aqueous medium, which is a pre-requisite for biomedical applications.