Hybrid organic-inorganic mesoporous silicates as optical nanosensor for toxic metals detection

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Date: Dec. 2014
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 13,695 words
Lexile Measure: 1480L

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Byline: Tarek. Fayed, Mohamed. Shaaban, Marwa. El-Nahass, Fathy. Hassan

The detection and quantification of toxic pollutants are more interest development at the nanoscale level. Optical nanosensors are one of the most efficient techniques used for the naked-eye detection of toxic metal ions. Recently, the design of optical nanosensors based on ligand embedded into mesoporous materials. Mesoporous materials are nanostructured materials, resulting in highly ordered arrays with large surface area and narrow pore size distribution in the mesoscale range (2-50 nm in diameter). These nanostructured materials have particularly interesting for their usage for several applications in the areas of adsorption, separation, catalysis, sensing and environmental cleanup. This review gives an overview of the preparation, properties, types and potential applications of these materials, especially in the area of sensing device. Also, the types of interactions between the ligand and mesoporous materials for the design of optical nanosensor were explained, with the main focus being on the covalent anchoring. Moreover, the toxicity of transition and heavy metals were discussed.

Nanostructured materials are those having properties defined by features smaller than 50 nm [Figure 1]. In this scale, especially below 5 nm, a significant improving of the physical, chemical and biological properties of the matter were observed. This class of materials has broad range of properties from fracture strength to electrical conductivity and stiffness (Sattler, 2010). Also, they offer a bridge between classical and biological branches of materials science with a wide range of scientific and technological applications in the fields of physics, chemistry, biology, medicine, engineering and also in real life such as in the US. There are more than 580 market products, including food, packaging, cosmetics, clothing and paints (Bhushan, 2004). Therefore, the current forecasts estimated about trillion 1 USD for the nanotechnology applications by 2015 (Roco, 2005).{Figure 1}

The synthesis techniques of nanostructured materials can be divided into top-down and bottom-up approaches. The top-down approach starts with materials with conventional crystalline microstructures, typically metals and alloys. Defects such as dislocations are introduced by severe plastic deformation as in equal channel pressing. The bottom-up approach includes many different techniques which are based on liquid or gas-phase processes. The properties of nanostructured materials depend on an extreme manner of the synthesis method as well as on the processing route. Therefore, it is important to select the most appropriate technique for preparation of nanostructured materials (Jones and Rao, 2002).

The interest in nanostructured materials arises from the small size of the building blocks and the high density of interfaces (surfaces, grain and phase boundaries). This improves new physical and chemical properties such as excellent mechanical properties and high selectivity. In addition, they can change its state (morphology, shape electronic, magnetic, and photonic, etc.) during its operation. Furthermore, these materials may also contain pores in the nanoscale range this so called nanoporous materials (Wang et al ., 2003).

Nanoporous materials are a subset of nanostructured and porous materials. Their important applications are due to their vast ability to adsorb and interact with atoms, ions and...

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Gale Document Number: GALE|A394844129