ABSTRACT
This chapter is intended as an introductory overview of the vast subject of inorganic nanoparticles (INPs), drawing focus on some of the more common synthesis techniques, such as the wet chemistry methods, and on some of the characteristics of inorganic nanoparticles and their applications. A broad brushstroke approach to the subject matter was chosen in the hope of providing researchers in the radiolabeling and tracer fields with a guide to current trends in the synthesis of INPs over the broad landscape and backdrop of nanoscience and nanotechnology. We hope that the material and references presented herein will assist the reader in selecting possible INPs of potential interest and aid in suggesting potentially new opportunities for research and applications in the field of radiolabeled nanoparticles. As many reviews, books,
and articles as possible were consulted for the preparation of this chapter. 2.1 IntroductionThe physics and chemistry of materials at sizes approaching those of atomic dimensions, i.e., of nanostructures and nanoparticles (NPs), are spawning new research strategies and paradigms in physics, chemistry, biology, materials science, and engineering. The unusual nature of such materials was noted in antiquity. Witness, for example, the glazes for early dynasty Chinese porcelain [1] and the unusual optical properties of the Roman Lycurgus cup [2]. During the 70s and 80s of the past century, studies in physics and chemistry started to focus attention on matter, then called ultra-fine particles (or inhomogeneous media when dispersed in a matrix), in the range of ~1 to 100 nm that displayed unusual and often unexpected electrical, optical and magnetic properties [3-8]. During the past two decades, inter-and multidisciplinary research has been broadening the scope of that attention to computation, systems, processes, manipulation, sensing, control, and analytical capabilities at the nanoscale [9-12]. These advances are presently fuelling further initiatives and growth in the rapidly growing disciplines of nanoscience and nanotechnology as the convergence of knowledge continues [13, 14]. Combined, research from these disciplines continues to impact discovery, development and change in societally important technology sectors such as electronics and photonics [15-17], telecommunications [18, 19], medicine [20-29], energy [30-32], catalysis [33], manufacturing [34], advanced materials, such as metal-NP plasmonics [35] and self-organizing nanoscale systems [36-38], and the environment [39-42]. Clearly, the nanoscale will provide numerous opportunities and challenges for innovative research and applications in the study and use of radiolabeling and tracer techniques. A “crash course” in nanotechnology is available for those wishing to have an overview [14a], as is the EC co-funded “roadmap” report on nanoparticles 2005 [14b] and a recent overview of nanochemistry [14c].At the nanoscale, the size of matter is dimensionally smaller than the characteristic length of a number of physical properties. As a consequence, the new and sometimes unexpected properties
of the nanoscale materials, as compared with those of the bulk, result from quantum confinement effects. Matter in the nanometer regime also has a high ratio of surface atoms to bulk atoms as the surface-area-to-volume ratio of the matter increases. Consequently, the electronic states of the surface and near-surface atoms become important as does any spill-out of electronic density, for example, outside of a NP. Nanoparticles and nanoscale materials of inorganic, bioceramic, carbon, and organic materials are the subjects of the introductory Chapters 2-5, respectively, and are the kinds of matter that will continue to contribute to the evolution of platforms, scaffolding, hierarchical and integrated structures during the next decades. 2.1.1 Nanomaterials and NanoparticlesNanomaterials generally have at least one dimension small enough to experience quantum confinement effects, usually in the size range of 1 to 100 nm. Thus, many materials of different compositions and shapes may be included, such as 3D clusters of atoms, compounds and materials, generally referred to as NPs, 2D sheets of clays, rings, dendrimers, graphenes, and graphene quantum discs, 1D materials, such as rods, tubes, wires, and filaments, and 0D “nanoparticles,” such as knots and quantum dots (QDs). Nanoparticles generally contain about 102 to 107 atoms. In the literature, some of the 2D and 1D materials, when small enough, are referred to as NPs, especially when dispersed in a medium. 2.1.2 Chapter ScopeThe aim of this chapter is to present a broad overview of INPs by introducing some of the synthesis techniques used to make them, some characteristics, and some representative applications. The discussion is meant to be illustrative rather than exhaustive and in this sense is selective and a bit arbitrary. Hence the reference list includes many books and review articles to which the reader is referred. No attempt is made to be comprehensive or all inclusive given the enormity of the literature and limited space of the chapter. The words synthesis, preparation, and methodology are used interchangeably.
