Composite and Nanocomposite Biosensors For Nitrate Analysis in Natural Waters Manzar Sohail Supervis

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Composite and Nanocomposite Biosensors For
Nitrate Analysis in Natural Waters Manzar Sohail
(Supervisor) Prof. Samuel Adeloju Water and
Sensor Research Group, School of Applied Sciences
and Engineering
Effect of pH
Introduction A biosensor is a device for the
detection of an analyte that combines a
biological component with a physicochemical
detector component.It consists of 3 parts the
sensitive biological element (biological material
(eg. tissue, microorganisms, enzymes, antibodies,
etc), a transducer (coverts biological signal to
detectable signal) and the detector element
(works in a physicochemical way optical,
piezoelectric electrochemical etc.). The Nitrate
reductase (NaR) based biosensors may provide a
simple, reliable and highly specific and in situ
measurement of nitrate in diverse type of
materials.

• metric detection.
• To explore the use of biosensors for monitoring
  nitrate in environmental materials.

Research Methodology Fabrication of
Biosensors Several biosensors for nitrate have
been constructed by electro-immobilization of
the Nitrate reductase (NaR) along with different
mediators (Med) Pyrrole has been used for
polymer matrices (PPy) on the surface of platinum
electrode to immobilize all the related
substances . Optimization For each biosensor
parameters such as pH, monomer analyte
concentrations, current density, polymerization
period, enzyme concentration, mediator/cofactor
and buffer concentrations were optimized
Typical potentiometric response of an optimised
nitrate biosensor
Cyclic Voltammetery
Voltammograms of PPy-NaR-Med films in 0.1 M
buffer (pH 7.3), (a) In absence of nitrate,
(b) 5mM Nitrate
The response for successive addition of nitrate
(5mM).
Scanning Electron Microscopy
Results and Discussion

• Aim of Study
• To Develop Highly Sensitive and Selective Novel
  Nitrate Biosensors by immobilization of Nitrate
  reductase (NaR).
• Objectives
• To explore the use of conducting polymers (e.g.
  Polypyrrole) for the entrapment of Nitrate
  reductase with suitable mediators.
• To investigate the use of nanometer thick single
  layer and bilayer arrangement to fabricate
  nanobiosensors with potentio-

Effect of Pyrrole concentration
(a)
(b)
(c)
(d)
Calibration plot showing the potential change vs.
increased concentration of nitrate (30-310 ppm
nitarte) for PPy-NaR-NADH biosensor
SEM images of a) PPy film only , b) PPy-NADH
film, c) PPy-NaR-NADH film and d) PPy-NaR-NADH
film after getting nitrate response.