392
A. Donia et al.
A gold nanoparticle (AuNP)-based sensor aimed to detect Hg(II) ions in aqueous
solution has been developed (Huang and Chang 2006). rhodamine B (RhB)
molecules, which are extremely fluorescent in bulk solution, can fluoresce poorly
when adsorbed onto AuNPs surfaces due to fluorescence resonance energy transfer as
well as collision with AuNPs. The existence of Hg in the solution leads to rhodamine
release and hence restores the fluorescence. It is noteworthy that the intensity of
restoring the fluorescence is linked with the amount of Hg in the solution. Modifying
the surface of nanoparticles with thiol ligands and addition of a chelating agent to
the solution provide specificity toward mercury. This nanosensor could detect an
exceptionally low levels of mercury concentration (2 ppb) with less than 10 min,
making it highly sensitive and selective.
Sensor for Escherichia coli detection using mannose encapsulated gold nanoparticles was developed because affinity of mannose toward type I pili of E. coli is
very high (Lin et al. 2002). In comparison with free mannose, mannose encapsulated
in nanoparticles showed greater affinity for E. coli. Instead of using a sensor that
is specific for a specific microorganism, silver nanoparticles have been proposed
based on a universal system to detect bacteria (Yonzon et al. 2005). Silver nanoparticles were functionalized with maltose, which exhibited affinity toward lectin or
concanavalin A (carbohydrate-binding protein). Magnetic nanoparticles functionalized with amine can be used to remove bacteria from the media (Huang et al. 2010).
The positive charge present on nanoparticle surface exhibited electrostatic interaction
with negative charge present on the surface of the bacteria. Bacterial removal efficacy from water samples was 88.5%. Gold nanoparticles were coated with IgG, and
the binding of IgG with protein was explored to sense pathogenic microorganisms
(Ho et al. 2004). This method may be applied for sensing Staphylococcus aureus
and Staphylococcus saprophyticus. IgG antibody was coated on magnetic nanoparticle surface to purify water. Applying an external magnet helps in removing the
trapped microorganisms. To detect microorganisms, quantum dots may possibly be
used as a fluorescent labeling system. Conjugation of an antibody with quantum
dots could be applied to detect pathogenic microorganisms’ viz. Giardia and cryptosporidium (Zhu et al. 2004). A study was successful in the concurrent sensing
of four different toxins, viz. cholera toxin, ricin, staphylococcal enterotoxin B, and
shiga-like toxin 1, using antibodies and quantum dot shellsquantum dot shells as
probes (Goldman et al. 2004).
The virulence of Bacillus anthracis is encoded by a tripartite exotoxin and
capsule. The sensor for Bacillus spores uses calcium dipicolinic acid as a biomarker.
Calcium dipicolinic acid is especially found in the spores without interfering
molecules. Deposition of spores on the silver film surface over nanosphere resulted
in a surface-enhanced Raman scattering spectrum unique to calcium dipicolinic
acid (Yonzon et al. 2005). Method of anthrax spore detection was developed
using a surface-assisted fluorescent sensing system (Yilmaz et al. 2010).Exotoxin
synthesized by Bacillus was detected using a nanosensor (Zhang et al. 2011).
A. Donia et al.
A gold nanoparticle (AuNP)-based sensor aimed to detect Hg(II) ions in aqueous
solution has been developed (Huang and Chang 2006). rhodamine B (RhB)
molecules, which are extremely fluorescent in bulk solution, can fluoresce poorly
when adsorbed onto AuNPs surfaces due to fluorescence resonance energy transfer as
well as collision with AuNPs. The existence of Hg in the solution leads to rhodamine
release and hence restores the fluorescence. It is noteworthy that the intensity of
restoring the fluorescence is linked with the amount of Hg in the solution. Modifying
the surface of nanoparticles with thiol ligands and addition of a chelating agent to
the solution provide specificity toward mercury. This nanosensor could detect an
exceptionally low levels of mercury concentration (2 ppb) with less than 10 min,
making it highly sensitive and selective.
Sensor for Escherichia coli detection using mannose encapsulated gold nanoparticles was developed because affinity of mannose toward type I pili of E. coli is
very high (Lin et al. 2002). In comparison with free mannose, mannose encapsulated
in nanoparticles showed greater affinity for E. coli. Instead of using a sensor that
is specific for a specific microorganism, silver nanoparticles have been proposed
based on a universal system to detect bacteria (Yonzon et al. 2005). Silver nanoparticles were functionalized with maltose, which exhibited affinity toward lectin or
concanavalin A (carbohydrate-binding protein). Magnetic nanoparticles functionalized with amine can be used to remove bacteria from the media (Huang et al. 2010).
The positive charge present on nanoparticle surface exhibited electrostatic interaction
with negative charge present on the surface of the bacteria. Bacterial removal efficacy from water samples was 88.5%. Gold nanoparticles were coated with IgG, and
the binding of IgG with protein was explored to sense pathogenic microorganisms
(Ho et al. 2004). This method may be applied for sensing Staphylococcus aureus
and Staphylococcus saprophyticus. IgG antibody was coated on magnetic nanoparticle surface to purify water. Applying an external magnet helps in removing the
trapped microorganisms. To detect microorganisms, quantum dots may possibly be
used as a fluorescent labeling system. Conjugation of an antibody with quantum
dots could be applied to detect pathogenic microorganisms’ viz. Giardia and cryptosporidium (Zhu et al. 2004). A study was successful in the concurrent sensing
of four different toxins, viz. cholera toxin, ricin, staphylococcal enterotoxin B, and
shiga-like toxin 1, using antibodies and quantum dot shellsquantum dot shells as
probes (Goldman et al. 2004).
The virulence of Bacillus anthracis is encoded by a tripartite exotoxin and
capsule. The sensor for Bacillus spores uses calcium dipicolinic acid as a biomarker.
Calcium dipicolinic acid is especially found in the spores without interfering
molecules. Deposition of spores on the silver film surface over nanosphere resulted
in a surface-enhanced Raman scattering spectrum unique to calcium dipicolinic
acid (Yonzon et al. 2005). Method of anthrax spore detection was developed
using a surface-assisted fluorescent sensing system (Yilmaz et al. 2010).Exotoxin
synthesized by Bacillus was detected using a nanosensor (Zhang et al. 2011).