Design and Development of Electrochemical DNA Nanobiosensors for Identification and Determination of Important Biomarkers

Salimian, Razieh | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51373 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Shahrokhian, Saeed; Kalhor, Hamid Reza
  7. Abstract:
  8. The main purpose of this Ph.D. Thesis is to develop DNA-based biosensors using Label-free approaches applying simple, inexpensive and fast electrochemical techniques to measure the biological markers of cancer.In the first part, a simple protocol for detection of specific-sequence DNA is introduced. In this method carbon nanotube is used as a hybridization indicator. This label-free system provides the advantage of eliminating additional labeling procedure. As the signal enhances in the presence of MWCNT and decreases in the presence of target, the fabricated sensor is known as a signal-off device. The oxidation signal of Fe(CN)63-/4- is followed as an analytical signal to detect target sequences. A good discrimination among complementary, non-complementary and mismatched sequences is achieved for this sensitive biosensor. This method may also shows potential applications in biomolecules detection.After examining the possibility of interaction of carbon nanotubes with the DNA probe without using the protracted process of tagging the DNA probe and using complex sandwich systems, in the second stage, the functionalized carbon nanotubes, with redox marker molecules, is utilized for detection of DNA hybridization. As a results, following the redox characteristic peak of thionine is used as a hybridization symbol and the relationship between current and log-concentration of the complementary strand of DNA target is found.In the third section, DNA-based platform consists of pyrrole-3-carboxilic acid and electrctrochemically reduced graphene nanosheets is fabricated for BRCA1 detection. The biosensor is investigated sequentially, for both PP3C and PP3C/ERGO platform for DNA detection. Graphene combined with polymer enhances the performance of biosensors in terms of sensitivity, selectivity, wide dynamic range (covers 7 orders of magnitude), low detection limit, good stability, and impressive reusability incorporated capability to discriminate mismatched DNA from complementary target making this platform as a new paradigm in biosensor design.The fourth section of the thesis is devoted to polyaniline as a hybridization indicator. A simple and efficient electrochemical platform for label-free detection of HBV DNA based on Au/PANI-
  9. Keywords:
  10. Modified Electrodes ; Hepatitis Beta Virus ; DNA-Based Electrochemical Biosensor ; Breast Cancer ; Biomarker ; Carbon/Metal/Polymer Nanostructures ; Label-free Detection ; Liver Cancer Biomarker

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