progress in the development of nanosensors and nanobiosensors for the detection of
some harmful water contaminating pathogens.
Contamination of bacterium Vibrio cholerae in the water is the cause of cholera.
Cholera toxin (CT) is secreted by the bacteria inside the intestines. Hence, the
nanosensors have been designed for detection of both CT-B and V. cholerae.
Majority nanosensors are based on the detection of CT-B due to the induction of
toxin uptake by the CT-sub unit B (CT-B). Antibodies like β-galactose and ganglioside GM1 can be used for label-based CT detection. Ahn et al., reported FRET-based
sensor for CT-B sensing, with theoretical LOD of 280 pM. Binding of cholera toxin
on Au NPs modified with β-galactose results in prohibition of fluorescence
quenching of QDs.
Legionella pneumophila is a harmful bacterium which can grow in the building
plumbing. People can get infected by this when they inhale this infective agent
contaminated aerosol, or through the bacterium species present in fresh water. This
bacterium can cause pneumonia like disease known as Legionnaires. For the detection of Legionella, Martin et al. (2015) designed a whole organism nanoprobe by
combination of amperometric transduction with a sandwich immunoassay for capturing the bacteria. They used poly(dopamine) (pDA) for modification of magnetic
NPs (MNPs) and then functionalized them with C-Ab which is a specific capture
antibody, to develop MNPs@pDA-C-Ab probes. The post incubation step was
introduction of horseradish peroxidase labelled antibody which acts as a second
detector. Then the immuncomplexes were captured on a screen-printed carbon
electrode (SPCE), using magnetic field. The assay exhibited specific detection of
Legionella and low LOD after certain preconcentration steps, and can be used as a
fast first screening method for water systems with high contamination.
Pseudomonas aeruginosa is a harmful pathogen present in sewage, faeces, soil
and water. It can be exposed through dermal contact with stool or infected water.
P. aeruginosa can also colonize in premise plumbing. It has been a cause of
nosocomial infection outbreaks in hospitals. Whole pathogen detection is mainly
used as the method for detection of P. aeruginosa. Bacteriophages, antibodies and
oligonucleotides recognition elements have also been used for the detection. In
2011, Wang et al. were the first to discover P. aeruginosa aptamer. Currently, in
their works, Yoo et al. and Hu et al. developed LSPR-based optical nanosensors with
nanotextured substrates for detection of P. aeruginosa. Yoo et al. (2015) followed a
fabrication approach with three steps. First, a glass slide was deposited with gold
(Au), this was followed by deposition of silica NPs, and then in the third step, a
second Au layer was deposited. Then they directly attached aptamers on the surface
of electrode via gold-thiol bond. On the other hand, Hu et al. used standard
nanosphere lithography for fabrication of biotinylated polyethylene glycol
(Bt-PEG) thiol/PEG thiol (1:3) nanosensor. Aptamers were immobilized using
Bt-PEG thiol via Bt-neutravidin-Bt linkage, PEG thiol spacer was used to reduce
the aptamers stearic hindrance. Hu et al. were successful in achieving low LOD
values and lower concentration linear response (10–10
3 CFU mL
À1 ) as compared to
Yoo et al. But in Yoo et al.’s work, LOD was obtained at low sample volume of 3 μL
(Hu et al. 2018).
5 Development of Environmental Nanosensors for Detection Monitoring. . .
129
some harmful water contaminating pathogens.
Contamination of bacterium Vibrio cholerae in the water is the cause of cholera.
Cholera toxin (CT) is secreted by the bacteria inside the intestines. Hence, the
nanosensors have been designed for detection of both CT-B and V. cholerae.
Majority nanosensors are based on the detection of CT-B due to the induction of
toxin uptake by the CT-sub unit B (CT-B). Antibodies like β-galactose and ganglioside GM1 can be used for label-based CT detection. Ahn et al., reported FRET-based
sensor for CT-B sensing, with theoretical LOD of 280 pM. Binding of cholera toxin
on Au NPs modified with β-galactose results in prohibition of fluorescence
quenching of QDs.
Legionella pneumophila is a harmful bacterium which can grow in the building
plumbing. People can get infected by this when they inhale this infective agent
contaminated aerosol, or through the bacterium species present in fresh water. This
bacterium can cause pneumonia like disease known as Legionnaires. For the detection of Legionella, Martin et al. (2015) designed a whole organism nanoprobe by
combination of amperometric transduction with a sandwich immunoassay for capturing the bacteria. They used poly(dopamine) (pDA) for modification of magnetic
NPs (MNPs) and then functionalized them with C-Ab which is a specific capture
antibody, to develop MNPs@pDA-C-Ab probes. The post incubation step was
introduction of horseradish peroxidase labelled antibody which acts as a second
detector. Then the immuncomplexes were captured on a screen-printed carbon
electrode (SPCE), using magnetic field. The assay exhibited specific detection of
Legionella and low LOD after certain preconcentration steps, and can be used as a
fast first screening method for water systems with high contamination.
Pseudomonas aeruginosa is a harmful pathogen present in sewage, faeces, soil
and water. It can be exposed through dermal contact with stool or infected water.
P. aeruginosa can also colonize in premise plumbing. It has been a cause of
nosocomial infection outbreaks in hospitals. Whole pathogen detection is mainly
used as the method for detection of P. aeruginosa. Bacteriophages, antibodies and
oligonucleotides recognition elements have also been used for the detection. In
2011, Wang et al. were the first to discover P. aeruginosa aptamer. Currently, in
their works, Yoo et al. and Hu et al. developed LSPR-based optical nanosensors with
nanotextured substrates for detection of P. aeruginosa. Yoo et al. (2015) followed a
fabrication approach with three steps. First, a glass slide was deposited with gold
(Au), this was followed by deposition of silica NPs, and then in the third step, a
second Au layer was deposited. Then they directly attached aptamers on the surface
of electrode via gold-thiol bond. On the other hand, Hu et al. used standard
nanosphere lithography for fabrication of biotinylated polyethylene glycol
(Bt-PEG) thiol/PEG thiol (1:3) nanosensor. Aptamers were immobilized using
Bt-PEG thiol via Bt-neutravidin-Bt linkage, PEG thiol spacer was used to reduce
the aptamers stearic hindrance. Hu et al. were successful in achieving low LOD
values and lower concentration linear response (10–10
3 CFU mL
À1 ) as compared to
Yoo et al. But in Yoo et al.’s work, LOD was obtained at low sample volume of 3 μL
(Hu et al. 2018).
5 Development of Environmental Nanosensors for Detection Monitoring. . .
129