Proceedings of MatricesFor IITTEP – ICoMaNSEd 2015
ISBN: 978-602-74204-0-3
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the sensing aparatus such as a working electrode. Electrodeposited polymers serve in sensors as convenient matrix for the immobilisation of sensing materials such as enzymes and
chemically acive materials. Good detectability and fast response are provided by redox reaction of substrate catalysed by an enzyme in the bulk of the polymer layer.
Electropolymerised films can be categorised as conducting or non-conducting polymers. Conducting films are widely used to enhance electron transfer, while non-conducting
polymers are important for their permselective characteristics [18].
4. Sensor Based on Electrodeposited Polymer
Electrodeposited polymers are attractive to be used for the development of sensors because the deposited film can be produced rapidly with controlled thickness and porosity and allows
the fabrication of reproducible layers. Immobilisation of the biorecognition element in an electrodeposited polymer is of considerable interest in the construction of the sensors. The
approach involves the electrooxidation of monomer containing enzyme to form a polymer with entrapped of sensing materials and also electropolymerisation of the monomer followed
by attachment of the sensing materials onto the matrix polymer. Electropolymerisation of monomer from a solution containing active material is the simplest method of immobilization
of recognition material. The mediator may also be incorporated in the monomer before electropolymerisation, or the mediator may be mixed with monomer and immobilised
simultaneously. However, electrochemical immobilisation seems only to be successful for nondenatured active materials. Various types of deposited polymers have been used to
immobilise different enzymes onto electrode surfaces [19]. Factors affecting the functioning of amperometric sensors are the electron transfer between the catalytic molecules, usually an
oxidase or dehydrogenase, and the electrode surface, most often involving the mediator.
Most electrochemical deposited polymer films used to immobilise active materials are conducting polymers such as polypyrrole, polyacetylene, polythyophene, polyaniline, and
polyindole. With a conducting polymer, the thickness of the polymer can be varied from thin to thick due to its conductivity. Conducting polymer-based membranes lack permselectivity
toward electroactive interferences such as ascorbic acid, uric acid and paracetamol that can be directly oxidised at the electrode surfaces. Modification of the electrode by building a
perselective membrane using nonconducting polymer is effective in improving the selectivity of enzyme electrodes to interferences. Furthermore, reproducible membrane films can be
made by using nonconducting polymers because the film is thin as the growth is self-limiting, and thus allows the construction of reproducible sensors [20]. Various nonconducting
polymers have been used for enzyme electrodes including overoxidised polypyrrole, polyphenols, polyphenylenediamine, polydichlorophenolindo-phenol and polytyramine where
the majority of the approaches have been mainly focused on the electropolymerisation of hetero-atom substituted aromatic compounds.
With the aim of developing novel passivating films to be used as permselective and thin membranes that are compatible as a matrix polymer for enzyme immobilisation, the use of
electrodeposited polytyramine has attracted attention in sensor construction, including biosensor [21-24] and chemical sensor [25]. In this respect, electrodeposited polytyramine is
an ideal polymer for the fabrication of enzyme electrodes as it contains an amine group to covalently attach the biorecognition molecule via a peptide linkage. Investigations of the
potential applications of polytyramine films for chemical sensor applications have been studied recenly in our group [26,27]. The versatility of polytyramine as an immobilisation
matrix for active materials produces highly reproducible sensing device, which have good long-term stability, are excellent at screening out interfering substances and provide
Proceedings of MatricesFor IITTEP – ICoMaNSEd 2015
ISBN: 978-602-74204-0-3
Keynote Invited Papers Page 20
considerable control over the response of the sensor. Some of them are explained in more detail in the application of the sensor biosensor and chemical sensor.
5. Sensor Applications
