| Summary: | An enzymeless biosensor was developed, with the knowledge of electrochemistry and
nanotechnology, for the sensitive and reliable detection of glucose. The main
motivation for the development of enzymeless biosensors was the lack of stability of
enzymes due to its intrinsic nature. The sensor consists of a Glassy Carbon Electrode
(GCE) that was modified by coating with different types of reagents. Cyclic
Voltammetry (CV) method was then used to detect glucose by oxidising them on the
GCE surface.
The reagents used in the coatings were chosen for a variety of reasons. Carbon
Nanotube (CNT) was first tested due to its unique nanostructure and high electrical
conductivity. Polyaniline (PANI) was then explored due to its potential in electrical
conductive properties. Finally, Gold (Au), a widely used catalyst in glucose biosensors,
was combined with other materials to increase the detection area of the sensor.
Two types of methodologies to deposit CNT onto the GCE were explored. First of
which was the use of Poly(allylamine hydrochloride) (PAH) to charge the GCE to
attract CNT dispersed in de-ionised water. Another was to first disperse CNT in a
surfactant Triton before drying them on the GCE.
The resulting layers were examined by Scanning Electron Microscopy (SEM), Field
Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray
Spectroscopy (EDX), Electrochemical Impedance Spectroscopy (EIS) and CV. The
gold deposited, CNT modified electrodes showed a high electrocatalytic activity
towards the oxidation of glucose in an alkaline medium. Further experiments were then
carried out to determine the number of layers of CNT dispersed in Triton and the
electrodeposition timing of gold.
It was discovered that the most sensitive CV detection of glucose occurred when two
layers of CNT was first dispersed in Triton, dried on GCE, and then electrodeposited
with Au nanoparticles using a run time of 60 s.
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