Development of a new immobilization procedure for detection of stphylococcal enterotoxin B (SEB) and Candida Albicans

Ertürkan, Deniz
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.
Citation Formats
D. Ertürkan, “Development of a new immobilization procedure for detection of stphylococcal enterotoxin B (SEB) and Candida Albicans,” M.S. - Master of Science, Middle East Technical University, 2012.