In this thesis, six different biosensors based on conducting polymers of poly
4-(2,5-di(thiophen-2-yl)-1H-pyrrole-1-l) benzenamine [poly(SNSNH2)] and poly(1-
(4-nitrophenyl)-2,5-di(2-thienyl)-1H-pyrrole [poly(SNSNO2)] were prepared.
Electrochemical technique was used for polymerization of conducting polymers and
two different immobilization techniques / crosslinking and adsorption were used for
immobilizing enzyme or microbial in the conducting polymer matrices. The
proposed biosensors were characterized and optimized. Optimum pH, thickness of
conducting polymer and biological material amount were determined. Linearity,
repeatability and operational stability experiments were performed. Carbon
nanotubes and gold nanoparticles were also added to the biosensing system to see the
effects of nanoparticles. The biosensors also used for ethanol and/or glucose
biosensing in commercial samples. In the first part of thesis, a biosensor was
designed by immobilizing Gluconobacter oxydans in poly(SNSNH2) matrix on
graphite electrode. The biosensor preparation method was a two-step procedure
where the cells were immobilized by adsorption on the surface after the
electropolymerization step.Use of dialysis membrane to cover the surface after immobilization conserves the
bioactive surface during the operation. The preparation is simple and not time
consuming. Systems proposed showed good linearity and repeatability as well as
high operational stability. Glucose amount in fruit juice, ethanol amount in vodka
and whisky were determined. In the second part of thesis, a second biosensor was
designed with electrochemical polymerization of 1-(4-nitrophenyl)-2,5-di(2-thienyl)-
1H-pyrrole via cyclic voltammetry on graphite electrode. Afterwards, Pseudomonas
fluorescens and Gluconobacter oxydans were immobilized successfully on the
conducting polymer matrix separately. The proposed biosensors showed good linear
range, and repeatability as well as high operational stability. In the third and fourth
parts, gold nanoparticle and carbon nanotube effects were studied on
poly(SNSNH2)/glucose oxidase biosensor, respectively. Covalent binding of glucose
oxidase was achieved to poly(SNSNH2) by the help of glutaraldehyde on the top of
graphite and carbon paste electrodes. Nanoparticle amount and optimum pH were
determined for both biosensors. After analytical characterization, glucose amount in
two fruit juices were determined with poly(SNSNH2)/GOx/AuNP and poly(SNSNH2)/
GOx/CNT biosensors. In the last part, biosensor was designed with immobilizing
alcohol oxidase in poly(SNSNH2) matrix via crosslinking with glutaraldehyde on
platinum electrode. The proposed biosensor was characterized and optimized in
terms of thickness, enzyme loading, pH, AuNPs, CNTs, linear range, repeatability
and operational stability.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12611803/index.pdf |
| Date | 01 April 2010 |
| Creators | Tuncagil, Sevinc |
| Contributors | Toppare, Levent |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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