Bioconjugation of monoclonal antibodies to chitosan coated ZnS quantum dots for rapid detection of Listeria and Vibrio species | |
| Author | Saw Marlar |
| Call Number | AIT Thesis no.FB-07-03 |
| Subject(s) | Chitosan Nanocrystals Bioconjugates |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. FB-07-03 |
| Abstract | The main aim of this study was to investigate the potential use of a natural cationic biopolymer, chitosan, in bioconjugation between quantum dots (QDs) and antibodies in an immunofluorescence assay for rapid detection of food pathogens. Colloidal QD of zinc sulphide doped with manganese and copper were synthesized by co-precipitation and in situ capping with 0.1% chitosan. The optical absorption spectra showed that the ZnS: Mn 2+ nanoparticles have an absorption edge at around 250 nm. The fluorescence spectra showed the emission peak at around 598 rim. Under UV exposure they glow with an orange color. Copper doped ZnS were also synthesized which have the absorption edge at around 280 nm and show the green luminescence at 480 nm. The chitosan capped QDs were conjugated with monoclonal antibodies solution by employing the electrostatic attraction between cationic chitosan and anionic antibodies at neutral pH, 20°C, 250 rpm for 4 hours. The QD-Ab bionanocomposites were used for imaging of Listeria monocytogenes and Vibrio parahaemolyticus. In order to avoid background fluorescence due to unattached nanoparticles, membrane filtration technique had to be used. Results with two pH buffers showed that best fluorescence were always obtained from the tests using acetate buffer (pH 5.5) rather than PBS (pH 7.4). Pathogens were labeled with non-specific MAb conjugated QD to determine the specificity of the assay. Results show conjugation of MAb to chitosan capped QD was successful, but with low specificity under the experimental conditions specified. In summary although nanoparticles were able to detect the pathogens, contaminants and specificity problems exist. From this study it is clear that QD bioconjugates need to be surface saturated with antibodies to prevent contaminants from giving false positive results and for increased specificity |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ;no. FB-07-03 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Rakshit, Sudip Kumar; |
| Examination Committee(s) | Athapol Noomhorm;Ranamukhaarachchi, S.; |
| Scholarship Donor(s) | Asian Institute of Technology fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2007 |