Microbial Nanobiotechnology in Nanocatalysis: Degradation …
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already been proven successfully, showing faster response in comparison with solidstate sensors (Kong et al. 2000). Solid-state sensors have the ability to be operated
at 200–600 °C, whereas single-walled carbon nanotubes can be performed at room
temperature. The enhanced reactivity shown by single-walled carbon nanotubes can
be explained by the fact that gaseous atoms can interact directly to these nanotubes
leading to a decrease or increase of electrically generated signal. Detection of glucose
in water has successfully been done using boron-doped silicon nanowires (Shao et al.
2005). Detection of calcium, proteins, and antibodies using these boron-doped
silicon nanowires was also achieved (Cui et al. 2001; Patolsky and Lieber 2005).
Nanowires can be employed in the real-time sensing to detect pathogens, chemical,
and biological agents in water, edibles, and air.
Nanotechnology has an essential role in targeting the previously stated problems
via several approaches. Nanoparticles can be treated with numerable kinds of biological as well as chemical ligands, which assist in improving their specificity. Many
ligands such as proteins, DNA, and enzymes have the ability to bind to nanoparticles with high specificity. Scientists can control the surface-to-volume ratio through
altering the shape and size of nanoparticles, increasing control over the interaction quality with the analytes. The capability to fabricate nanoparticles of different
metals aids in increasing both conductivity and sensitivity. Nanoparticle sensors may
be synthesized to sense organic or inorganic contaminants and biological organisms.
Using porous silicon, semiconductor nanostructures can be used to detect organic
contaminants. Photoluminescence, which is a feature of porous silicon, could be
quenched in the existence of inorganic or organic molecules.
Using the previous approach, pesticide concentration as low as 1 ppm can be easily
detected (Stefano et al. 2005). Organic contaminants can quench photoluminescence
due to the transfer of energy to the triple substrate of the organic substrate and
the transfer of electron from the conduction silicon nanocrystal band to the empty
quencher orbital. Carbon nanotube-based sensors can be employed to sense several
gases such as NO 2 , NH 3 , or O 3 . Electrical resistance of the nanotubes significantly
changes upon contact with the previous gases. Therefore, it can be easily detected.
Several heavy metals such as Cd, Pb, or Hg could be detected using nanoparticles via
calorimetric or fluorescence-based method. The previous studies have functionalized
gold nanoparticles with 11-mercaptoundecanoic acid or chitosan to detect heavy
metal ions such as Cd, Pb, or Hg (Kim et al. 2001; Sugunan et al. 2005). The binding
of heavy metal ions to the metal chelators such as chitosan and mercaptoundecanoic
acid leads to aggregation of the nanoparticles, making wavelength absorption shift
and change of color from red to blue. Although this is not only for a specific metal
ion, it is very sensitive toward the recognition of heavy metal ions in general. Specific
sensors were developed based on a similar principle. A sensor for lead detection was
developed using gold nanoparticles, which were coated with lead-dependent DNA
enzymes (Liu and Lu 2004). In the absence of lead, enzymes triggered aggregation
of nanoparticles. Alternatively, in the presence of lead, activated enzyme cleaved
the substrate and there is inhibition of the aggregation, resulting in a wavelength
absorption shift.
391
already been proven successfully, showing faster response in comparison with solidstate sensors (Kong et al. 2000). Solid-state sensors have the ability to be operated
at 200–600 °C, whereas single-walled carbon nanotubes can be performed at room
temperature. The enhanced reactivity shown by single-walled carbon nanotubes can
be explained by the fact that gaseous atoms can interact directly to these nanotubes
leading to a decrease or increase of electrically generated signal. Detection of glucose
in water has successfully been done using boron-doped silicon nanowires (Shao et al.
2005). Detection of calcium, proteins, and antibodies using these boron-doped
silicon nanowires was also achieved (Cui et al. 2001; Patolsky and Lieber 2005).
Nanowires can be employed in the real-time sensing to detect pathogens, chemical,
and biological agents in water, edibles, and air.
Nanotechnology has an essential role in targeting the previously stated problems
via several approaches. Nanoparticles can be treated with numerable kinds of biological as well as chemical ligands, which assist in improving their specificity. Many
ligands such as proteins, DNA, and enzymes have the ability to bind to nanoparticles with high specificity. Scientists can control the surface-to-volume ratio through
altering the shape and size of nanoparticles, increasing control over the interaction quality with the analytes. The capability to fabricate nanoparticles of different
metals aids in increasing both conductivity and sensitivity. Nanoparticle sensors may
be synthesized to sense organic or inorganic contaminants and biological organisms.
Using porous silicon, semiconductor nanostructures can be used to detect organic
contaminants. Photoluminescence, which is a feature of porous silicon, could be
quenched in the existence of inorganic or organic molecules.
Using the previous approach, pesticide concentration as low as 1 ppm can be easily
detected (Stefano et al. 2005). Organic contaminants can quench photoluminescence
due to the transfer of energy to the triple substrate of the organic substrate and
the transfer of electron from the conduction silicon nanocrystal band to the empty
quencher orbital. Carbon nanotube-based sensors can be employed to sense several
gases such as NO 2 , NH 3 , or O 3 . Electrical resistance of the nanotubes significantly
changes upon contact with the previous gases. Therefore, it can be easily detected.
Several heavy metals such as Cd, Pb, or Hg could be detected using nanoparticles via
calorimetric or fluorescence-based method. The previous studies have functionalized
gold nanoparticles with 11-mercaptoundecanoic acid or chitosan to detect heavy
metal ions such as Cd, Pb, or Hg (Kim et al. 2001; Sugunan et al. 2005). The binding
of heavy metal ions to the metal chelators such as chitosan and mercaptoundecanoic
acid leads to aggregation of the nanoparticles, making wavelength absorption shift
and change of color from red to blue. Although this is not only for a specific metal
ion, it is very sensitive toward the recognition of heavy metal ions in general. Specific
sensors were developed based on a similar principle. A sensor for lead detection was
developed using gold nanoparticles, which were coated with lead-dependent DNA
enzymes (Liu and Lu 2004). In the absence of lead, enzymes triggered aggregation
of nanoparticles. Alternatively, in the presence of lead, activated enzyme cleaved
the substrate and there is inhibition of the aggregation, resulting in a wavelength
absorption shift.