Cadmium selenide (CdSe) nanoparticles have been synthesized at three different temperatures (Room temperature (RT), 60°C and 80°C) by chemical route using cadmium acetate, sodium selenosulphate as cadmium and selenium precursors respectively. Triethanolamine and ammonia were used as capping and pH controlling agent. The particle size and crystalline structure of the synthesized nanoparticles were determined by transmission electron microscope (TEM). The analysis of TEM images indicated that CdSe nanoparticles possess cubic structure with particle radius is below 60nm. Thermal stability of CdSe nanoparticles are determined by thermogravimeteric analysis indicating weight loss region is between 650ºC-800ºC. The antimicrobial properties of as synthesized nanoparticles at different temperatures were investigated using gram-positive (Staphylococcus aureus, Bacillus subtilis) and gram-negative bacteria (Pseudomonas aeruginosa, Serratia marcescens and Proteus vulgaris) as test organism. The bactericidal effect of CdSe nanoparticles dispersed in acetone medium were determined by measuring the diameter of inhibition zone in gel diffusion tests. Bacterial sensitivity to nanoparticles was found to vary depending on the microbial species. Gel diffusion test revealed greater effectiveness of the cadmium selenide nanoparticles with Staphylococcus aureus and Bacillus subtilis compared to other test organisms. Bacillus subtilis exhibited maximum susceptibility to CdSe nanoparticles synthesized below 80°C. Further, we studied minimum inhibitory concentration of CdSe nanoparticles against the test cultures which is described in the paper.
