Fast and accurate detection of pathogens such as bacteria, their toxins and viruses at
low concentrations is very important. The conventional techniques are time
consuming where expensive equipment is required with a consumption of excess
amount of blood from patients. Recently, immunosensors are used for the detection
of pathogens because they are miniature, sensitive, biocompatible and require low
power. According to the Centers for Disease Control and Prevention (CDCP), 76 million
people become ill due to food poisoning and 5,000 of them die each year in United
States. In addition, SEB causing food poisoning has listed as a bioterrorism agent by
CDCP. Thus, accurate and selective detection in short time is very important for SEB
detection.
Candida albicans (C. albicans) is a yeast-like fungus and causes anxiety, insomnia,
constipation, hiatal hernia, panic attacks, denture-induced stomatitis, angular
cheilitis, gingivitis and prosthetic implant infections. In addition, it can cause death if
the immune system of patient is under failure due to cancer, chemotherapy and
AIDS.
In this study, a new procedure was developed. A simple and highly selective
homogeneous sandwich immunoassay was obtained for ultrasensitive detection of
Staphylococcal Enterotoxin B (SEB) using Atomic Force Microscopy (AFM) and
Surface Enhanced Raman Scattering (SERS) probe. In the developed procedure,
thiolated antibodies were produced and SEB was immobilized on the biosensor
surface using these antibodies. In addition, theory of SEB adsorption on a gold
surface was studied and the reaction rate constant between SEB and its toxin was
calculated. Moreover, C. albicans was detected using the developed procedure by a
microscope. Thus, it is proved that, the developed procedure can be used for
detection of different pathogens. Furthermore, nonspecific interaction between SEB
antibody and BSA was determined in this study. Also, the developed procedure and a
procedure found from literature were compared. In the procedure used in the
literature (second procedure), self-assembled monolayer (SAM) was formed and
antibodies were immobilized on SAM. After formation of sandwich structure, the
roughness of gold surface and the minimum concentration of SEB detected were
determined by AFM and SERS, respectively.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614435/index.pdf |
| Date | 01 July 2012 |
| Creators | Erturkan, Deniz |
| Contributors | Ozgen, Canan |
| 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 METU campus |
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