Recent Advances in Nanoscience and Technology

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In this chapter the main experimental methods used for the synthesis of metal nanostructures in aqueous colloidal form are considered. For convenience, consideration was made separately for noble metals and magnetic metals, even the most of methods are generally common for both groups. While the chemical reduction of metal ions still remains the main method for such synthesis, laser ablation in water solutions as well as combinations of these two methods became more and more popular, and can bring more promising results in the nearest future.

Design of consistant and facile methods for the synthesis of silver nanoparticles is a significant forward direction in the field of application of materials science, nanotechnology and medicine. A number of methods have been suggested in the literature for the synthesis of nonagglomerated nanoparticles. These include natural and synthetic polymers, biological macromolecules, latex particles, mesoporous inorganic materials, dendrimers, microgels or hydrogels, colloidal systems and others. In this chapter, we review the latest development of various surfactant based synthesis of metal nanoparticles with a few illustrations on how the stability, morphology and complexity of nanosystems differs with current methodologies.

The water in oil microemulsion or reverse micelle has been used in the past two decades for the synthesis of many different types of nanoparticles. The nano meter sized aqueous cores of the reverse micelle provide an appropriate stabilized environment for the production of nanoparticles of fairly uniform size, through chemical reactions occurring in the core and it also acts as steric stabilizers to inhibit the aggregation of nanoparticles formed. The water in oil microemulsion has been used to synthesize different types of core nano particles (metals, and semiconductors) as well as core-shell/ composite nanoparticles. This article describes the preparation techniques, and the various techniques used to characterize these core and core-shell nanoparticles as well as insights in to the effects of various process parameters on the terminal particle size. A brief review of our modeling work based on stochastic population balance is also presented, which can be used to describe the formation of both core and coreshell nanoparticles. In addition, we have also presented a brief review of the work on the synthesis of anisotropic nanostructures like nanorods and nanowires by templating against surfactant micelles and reverse micelles. Some findings of our work, addressing the engineering issues, such as possibility of reusing surfactant and organic phases are also included in this article.

Metal nanostructures with the size range of 1-100 nm, featuring unique physical and chemical properties that arise from their quantum size effects and high surface areas, have been the focus of recent scientific research. Among a variety of synthetic methods, the photoreduction method represents a promising strategy for controlled synthesis of metal nanostructures with different sizes, shapes and composition. In this review, the latest development on synthesis of metal nanostructures by UV radiation, γ-ray radiation, and laser radiation methods will be overviewed with specific examples to illustrate how to generate metal nanostructures with unusual structural specialty and complexity. The perspectives on combination of this method with solution processing and interfacial reactions are given.

This chapter is mainly focused on current novel approaches that have been made to synthesize metal nanoparticles with predetermined shape, size, and fair stability using self assembly process. It has also demonstrated the influence of various inorganic, organic compounds, polymer, and biological molecules on the nanostructures of particles.

The scientific and industrial need for novel composite materials and nanoparticles has opened new paths and led to significant advances in the field of nanocomposites. A number of nanosystems can be designed based on their unique physico-chemical structures for direct biomedical applications. This review is focused on the most novel strategies and trends to design metal nanoparticles including thermal decomposition, chemical reduction and green methods. These methods can be applied to fabricate polymer metal nanocomposites into different forms: core –shell, hollow core- shell nanoparticle system, metal nanoparticles in hydrogel matrix and layer by layer assembly systems. The resulting new class of materials found fascinating interest in antimicrobial, drug delivery and in catalysis.

Hydrogels containing silver nanoparticles have a variety of biomedical applications because of the excellent compatibility of hydrogels with biological molecules, tissues, cells, and exceptional antibacterial properties of silver nanoparticles. Here we report the design and development of various hydrogel networks that can be employed as matrices to grow and form metal nanoparticles. This behavior is achieved because of their enormous hydrophilic groups and free space between gel networks that extend not only stabilization but also participate in reduction process. This chapter provides an in-depth review of various hydrogel systems that can be employed for nanoparticles synthesis.

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