impermeable and turbid media, hence eliminating the necessity of sample purification steps, unlike the cases of optical and electrochemical based sensors. Also, most
of the practical samples don’t contain magnetic properties, hence, the MRWs-based
nanosensors can be used for background-free detections of harmful water pollutants.
In their work, Zhang et al. (2017b) have summarized the recent advances on MRWsbased nanosensors.
5.3.2 On the Basis of Shape and Types of Nanomaterials Used
for Fabrication of Nanosensors
The type of nanomaterials and their structure plays an important role in determining
their chemical and physical properties. By variation in their synthesis techniques and
precursors used for fabrication of nanomaterials, various morphologies can be
obtained like rods, dendimers, nanocubes, nanocones, nanowires, nanoflowers,
nanofibers, quantum dots, nanosheets, etc. Also, different kinds of nanomaterials,
like carbon-based, metal, metal oxides, etc. can be used for fabricating nanosensors
for environmental applications. Here we are summarizing some major classes of
nanomaterials and their applications for fabrication of nanosensors analyzing environmental samples.
5.3.2.1 Carbon-Based Nanomaterials
Carbon-based nanomaterials have been implemented as suitable transduction
elements for fabrication of highly selective and sensitive sensors due to their unique
geometry, broad potential window, rapid electron transfer properties, low residual
current, easy renewal and modification of their surfaces, and optical properties
(Nehra et al. 2019).
These carbon-based nanomaterials can be classified on the basis of the number of
dimensions in nanorange as:
• 0 D, with all the three dimensions in nanoscale (fullerenes, nanodiamond, carbon
dots, etc.)
• 1 D, with two dimensions in nanoscale (carbon nanofibres (CNFs), carbon
nanotubes (CNTs), etc.)
• 2 D, with one dimension in nanoscale (graphene, graphene oxide, etc.)
Due to their excellent electrocatalytic behaviour, and ability to stay chemically
inert during redox reactions, these materials have found huge application as electrochemical sensors, and have been used for the detection of a numerous environmental
contaminants. Carbon-based materials have been used for modification of working
electrode surfaces for three and two electrode electrochemical detection systems, and
used for sensing analytes using electrochemical techniques like voltammetry,
amperometry, impedance, etc. (Nehra et al. 2019). These materials have also been
used as platforms for immobilization of biomolecules for designing biosensors.
5 Development of Environmental Nanosensors for Detection Monitoring. . .
105
of the practical samples don’t contain magnetic properties, hence, the MRWs-based
nanosensors can be used for background-free detections of harmful water pollutants.
In their work, Zhang et al. (2017b) have summarized the recent advances on MRWsbased nanosensors.
5.3.2 On the Basis of Shape and Types of Nanomaterials Used
for Fabrication of Nanosensors
The type of nanomaterials and their structure plays an important role in determining
their chemical and physical properties. By variation in their synthesis techniques and
precursors used for fabrication of nanomaterials, various morphologies can be
obtained like rods, dendimers, nanocubes, nanocones, nanowires, nanoflowers,
nanofibers, quantum dots, nanosheets, etc. Also, different kinds of nanomaterials,
like carbon-based, metal, metal oxides, etc. can be used for fabricating nanosensors
for environmental applications. Here we are summarizing some major classes of
nanomaterials and their applications for fabrication of nanosensors analyzing environmental samples.
5.3.2.1 Carbon-Based Nanomaterials
Carbon-based nanomaterials have been implemented as suitable transduction
elements for fabrication of highly selective and sensitive sensors due to their unique
geometry, broad potential window, rapid electron transfer properties, low residual
current, easy renewal and modification of their surfaces, and optical properties
(Nehra et al. 2019).
These carbon-based nanomaterials can be classified on the basis of the number of
dimensions in nanorange as:
• 0 D, with all the three dimensions in nanoscale (fullerenes, nanodiamond, carbon
dots, etc.)
• 1 D, with two dimensions in nanoscale (carbon nanofibres (CNFs), carbon
nanotubes (CNTs), etc.)
• 2 D, with one dimension in nanoscale (graphene, graphene oxide, etc.)
Due to their excellent electrocatalytic behaviour, and ability to stay chemically
inert during redox reactions, these materials have found huge application as electrochemical sensors, and have been used for the detection of a numerous environmental
contaminants. Carbon-based materials have been used for modification of working
electrode surfaces for three and two electrode electrochemical detection systems, and
used for sensing analytes using electrochemical techniques like voltammetry,
amperometry, impedance, etc. (Nehra et al. 2019). These materials have also been
used as platforms for immobilization of biomolecules for designing biosensors.
5 Development of Environmental Nanosensors for Detection Monitoring. . .
105