Development of qcm based dna biosensors for detection of genetically modified organisms

Karamollaoğlu, İrem
A great effort has been recently devoted to the development of new devices for the detection of specific sequences of DNA, due to increasing need of label - free, fast, cheap, and miniaturized analytical systems able to detect target sequences for screening purposes, especially in food industry for genetically modified organisms (GMOs). In this study, development of a QCM - based DNA biosensor for the detection of the hybridisation of CaMV 35S promoter sequence (P35S) was investigated. Attention was focused on the choice of the coating chemistry that could be used for the immobilisation of probe sequences on the gold surface of the quartz crystal. Two immobilisation procedures were tested and compared considering the amount of the immobilised probe, the extent of the hybridisation reaction, the possibility of regeneration and the absence of non - specific adsorption. The two coating methods were based on the use of self - assembled monolayers. One of them employed the interaction between the thiol and gold for the immobilisation of a thiolated P35S probe, while the other employed formation of functionalised aldehyde groups by ethylenediamine plasma polymerization on the gold surface for the immobilisation of amined P35S probes through gluteraldehyde activation. Results indicated that immobilisation of a thiolated probe provides better immobilisation characteristic, higher sensitivity for the detection of the hybridisation reaction, absence of non - specific adsorption and a higher stability with respect to the regeneration step. The optimised immobilisation procedure for the thiolated probe was used for the detection of P35S sequence in PCR - amplified DNAs and in real samples of pflp - gene inserted tobacco plants that produce ferrodoxin like protein additionally. Fragmentation of the genomic DNAs were achieved by digestion with restriction endonucleases and sonication. The obtained results from the fragmented genomic DNAs demonstrated that it is possible to detect the target sequence directly in non-amplified genomic DNAs by using the developed QCM - based DNA biosensor system. The developed QCM-based DNA biosensor represented promising results for a real-time, label - free, direct detection of DNA samples for the screening of GMOs.


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This thesis is focused on the development of a gene delivery system, especially for the purpose of DNA vaccination. DNA expression vectors have the potential to be useful therapeutics for a wide variety of applications. A carrier system was designed to realize the delivery of genes to cells and the promotion of controlled adequate expression in the target cells. The low gene delivery efficiency observed with systems composed of polyplexes is mainly due to low stability of polycation e.g polyethylenimine-DNA...
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Tomato, which is one of the most important component of human diet, has been genetically modified to develop some properties like delayed ripening and insect resistance. In order to give a choice to the consumer, it is necessary to detect and label GM foods. This study was carried out to detect genetically modified tomato samples purchased from different food markets of Turkey. PCR method was used to detect genetically modified insect resistant tomatoes. The DNAs of collected samples were isolated according...
Cutting edge: Role of toll-like receptor 9 in CpG DNA-induced activation of human cells
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Genetically modified organisms (GMOs) are being widely used worldwide. Every country has a different legislation regarding the allowed events and GMO levels. This creates the great need for GMO detection. In this study, LAMP assay was used for GMO detection owing to its high sensitivity with the genetically modified organisms; Bt11 maize, GT73 Roundup Ready canola, and transgenic Nicotiana tabacum, targeting the sequences most commonly used in GMO constructions; 35S promoter and Figwort mosaic virus (FMV) s...
Live-cell imaging of Pol II promoter activity to monitor gene expression with RNA IMAGEtag reporters
SHIN, Ilchung; RAY, Judhajeet; Gupta, Vinayak; İlgü, Müslüm; Beasley, Jonathan; BENDICKSON, Lee; MEHANOVIC, Samir; Kraus, George A.; Nilsen-Hamilton, Marit (Oxford University Press (OUP), 2014-01-01)
We describe a ribonucleic acid (RNA) reporter system for live-cell imaging of gene expression to detect changes in polymerase II activity on individual promoters in individual cells. The reporters use strings of RNA aptamers that constitute IMAGEtags (Intracellular MultiAptamer GEnetic tags) that can be expressed from a promoter of choice. For imaging, the cells are incubated with their ligands that are separately conjugated with one of the FRET pair, Cy3 and Cy5. The IMAGEtags were expressed in yeast from ...
Citation Formats
İ. Karamollaoğlu, “Development of qcm based dna biosensors for detection of genetically modified organisms,” Ph.D. - Doctoral Program, Middle East Technical University, 2007.