in these electrochemical biosensors converts biological signals into readable output
signals. Electrodes used in biosensors allow the conversion of biological signals
into a readable output signal. Modifications by specific biochemical (DNA,
enzymes or cells). These electrochemical biosensors may be any type: potentiometric, voltammetric or Amperometric on the basis of output method applied.
Electrochemical biosensors can be sub categorized as biocatalytic or affinity sensors
on the basis of biological molecule used for modification. Electro-biocatalytic
sensors are modified with biological entities (enzymes) that recognizes a specific
target and induces a response of an electroactive molecule. AChE inhibition-based
electrochemical biosensing has been proved to be easy, fast and extra sensitive
method for pesticide such as paraoxoon, parathion, carbofuran and methemiodophos. Immunoassay based electrochemical sensors have been reported to be applied
in the detection of Picloram, carbofuran, Atrazine and other pesticides. On the other
hand, electro-affinity sensors have a binding recognition element (such as antibodies) and produces signals when they are coupled to target molecules [109].
Extensive literature is already been done for Pb(II), Cu(II), Hg(II), Cd(II) etc.
Application of nanomaterials adds the benefit of smaller size and higher surface
area to the electrodes.
4.4 Nanowire-Based Electrochemical Sensors
Application of nanowires can be other possible strategy for enhancing
surface-to-volume ratio, and promoting the electrochemical sensitivity of sensors
for the detection of analyte. Nanowires made of conductive or semiconductive
materials (Au, Ag, CuO) depending on the nature analyte to be detected. The easier
mode of preparation, higher surface-to-volume ratio, and increased stability due
crystallinity, higher sensitivity and selectivity suggests them to be used effectively
in sensing devices. CuO nanowires anchored on SWCNTs in an electrochemical
sensor can be used for the detection of organophosphorus pesticides (parathion or
Malathion) used in the field of agriculture. CuO-SWCNTs are much stable and
show high specificity for Malathion and effective selectivity against pesticides,
metal ions or cations and carbohydrates [58]. Silicon nanowires-supported
AChE-based electrochemical sensors were used for the determination of
organophosphate pesticides [110].
4.5 Paper-Based Electrochemical Biosensors
Paper is becoming an increasingly common support for developing microfluidic
devices and biosensors because of their unique properties such as porosity, liquid
wicking and affinity for surface to a number of analyte, etc. Such devices are much
portable, on-site, and real-time monitoring, thereby establishing them for large
Materials in Electrochemical Detection of Water Pollutants
175
signals. Electrodes used in biosensors allow the conversion of biological signals
into a readable output signal. Modifications by specific biochemical (DNA,
enzymes or cells). These electrochemical biosensors may be any type: potentiometric, voltammetric or Amperometric on the basis of output method applied.
Electrochemical biosensors can be sub categorized as biocatalytic or affinity sensors
on the basis of biological molecule used for modification. Electro-biocatalytic
sensors are modified with biological entities (enzymes) that recognizes a specific
target and induces a response of an electroactive molecule. AChE inhibition-based
electrochemical biosensing has been proved to be easy, fast and extra sensitive
method for pesticide such as paraoxoon, parathion, carbofuran and methemiodophos. Immunoassay based electrochemical sensors have been reported to be applied
in the detection of Picloram, carbofuran, Atrazine and other pesticides. On the other
hand, electro-affinity sensors have a binding recognition element (such as antibodies) and produces signals when they are coupled to target molecules [109].
Extensive literature is already been done for Pb(II), Cu(II), Hg(II), Cd(II) etc.
Application of nanomaterials adds the benefit of smaller size and higher surface
area to the electrodes.
4.4 Nanowire-Based Electrochemical Sensors
Application of nanowires can be other possible strategy for enhancing
surface-to-volume ratio, and promoting the electrochemical sensitivity of sensors
for the detection of analyte. Nanowires made of conductive or semiconductive
materials (Au, Ag, CuO) depending on the nature analyte to be detected. The easier
mode of preparation, higher surface-to-volume ratio, and increased stability due
crystallinity, higher sensitivity and selectivity suggests them to be used effectively
in sensing devices. CuO nanowires anchored on SWCNTs in an electrochemical
sensor can be used for the detection of organophosphorus pesticides (parathion or
Malathion) used in the field of agriculture. CuO-SWCNTs are much stable and
show high specificity for Malathion and effective selectivity against pesticides,
metal ions or cations and carbohydrates [58]. Silicon nanowires-supported
AChE-based electrochemical sensors were used for the determination of
organophosphate pesticides [110].
4.5 Paper-Based Electrochemical Biosensors
Paper is becoming an increasingly common support for developing microfluidic
devices and biosensors because of their unique properties such as porosity, liquid
wicking and affinity for surface to a number of analyte, etc. Such devices are much
portable, on-site, and real-time monitoring, thereby establishing them for large
Materials in Electrochemical Detection of Water Pollutants
175