Synthesis and characterization of organic molecules passivated cadmium sulphide nanostructures for biological applications

Abstract

Nanostructured materials are novel materials that are scientifically interesting and hold a great potential for numerous technological applications. Size is one of the distinguishing characteristics of nanomaterials. Their properties are different from and often superior to those of conventional coarse - grained polycrystalline materials and also amorphous alloys of the same composition. Nanomaterials can have one, two or three dimensions in the nanoscale. Nanomaterials show promising applications in various fields and in many products like paints, fuel cells, batteries, fuel additives, catalysts, transistors, lasers and lighting, lubricants, integrated circuitry, medical implants, water purifying agents, self - cleaning windows, sunscreens and cosmetics, explosives, disinfectants, abrasives, food additives etc. The widest use of nanomaterials has been as drug delivery systems, then as biosensors and for diagnostic imaging. This thesis is related to the study of synthesis and characterization of surface newlinepassivated CdS nanostructures. Quantum behavior becomes increasingly prominent as structures become smaller. The CdS semiconductors used for this study are wide optical gap semiconductors. The optical gap lies within solar energy spectrum. These materials possess the necessary criteria, which is very important for both emissive as well as photovoltaic applications so as to make them potential candidates in solar cells. Apart from this, CdS nanoparticles find applications as fluorescent biological labels. The entire work, presented in the thesis, has been divided into seven chapters. The results obtained in the present work are in good agreement with the responses observed earlier for various nanomaterials. Chapter 1 deals with the general introduction of nanotechnology. The basic concepts of semiconducting nanomaterials and the size dependent properties have been illustrated. Classification of nanocrystalline materials on the basis of different parameters is discussed.