The Impact of Pesticides - Academy Publish

surface area and be easily modified with a wide range of biomolecules they enablethe fabrication of biosensors with a plethora of sensing possibilities. On thenanoscale size (1–100 nm) many materials show interesting quantum effects. Theobserved strong Plasmon absorption bands, arising from the collective oscillation of“roving” electrons on the particle surface, often serve as a probe to monitor theinteraction with surface-bound molecules. The nanoparticles in the diameter rangeof 1–10 nm would display electronic structures, reflecting electronic band structureof the nanoparticles, owing to quantum-mechanical rules (Alivisatos, 1996). Theresulting physical properties are neither of the bulk metal nor of the molecularcompounds but they strongly depend on the particle size, interparticle distance, andnature of the protecting organic shell and shape of the nanoparticles (Brust andKiely, 2002). The gold nanoparticles (AuNPs) are the most stable metalnanoparticles and are expected to be key materials and building blocks fornanomaterials and nanodevices in the 21 st century, because of their fascinatingaspects in materials science, size-related electronics, magnetic and optical properties(quantum size effect), and their applications in catalysis and biology (Singh et al,2010).Nanostructured Metal OxidesNanostructured metal oxides such as CeO 2 , SnO 2 , Fe 3 O 4 , MnO 2 , Sb 2 O 3 , TiO 2 , ZnOand ZrO 2 have been found to exhibit interesting properties such as large surface-tovolumeratio, high surface reaction activity, high catalytic efficiency, and strongadsorption ability that make them potential candidate materials for the fabrication ofa biosensor (Kerman et al, 2008; Chow et al, 2005; Li et al, 2006). The large surfacearea of nanomaterials is likely to provide a better matrix for the immobilization ofdesired enzyme, leading to increased enzyme loading per unit mass of particles.Moreover, the multipoint attachment of enzyme molecules to nanomaterials surfacesreduces protein unfolding resulting in enhanced stability of enzyme attached to thenanoparticles surface. The enzyme-attached nanoparticles facilitate enzymes to actas free enzymes in solution that in turn provide enhanced enzyme– substrateinteraction by minimizing potential aggregation of the free enzyme (Pandey et al,2007).Quantum DotsQuantum dots (QDs) or nanocrystals, are a special class of materials known assemiconductors, which are crystals composed of periodic groups of II-VI, III-V, orIV-VI materials. QDs, one of these nanomaterials, are nearly sphericalsemiconductor particles with diameters from 2 to 10 nm, comprising 200 to 10,000atoms. QDs have size-controlled luminescence functions, which mean the samematerial with variable sizes can exhibit different colors under the excitation of anappropriate wavelength; broad absorption spectra; and narrow emission spectra,which mean simultaneous excitation of different colored QDs by a singlewavelength (Han et al. 2001; Gill et al. 2008). The main advantages of QDscompared to the other nano materials is their nano scale size similar to the proteins,AcademyPublish.org - The Impact of Pesticides398